Go中的日志及第三方日志包logrus
<svg xmlns="http://www.w3.org/2000/svg" style="display: none"><path stroke-linecap="round" d="M5,0 0,2.5 5,5z" id="raphael-marker-block" style="-webkit-tap-highlight-color: rgba(0, 0, 0, 0)"></path>
</svg>
<p>有别的语言使用基础的同学工作中都会接触到日志的使用，Go中自然也有log相关的实现。Go log模块主要提供了3类接口，分别是 “Print 、Panic 、Fatal ”，对每一类接口其提供了三种调用方式，分别是 “Xxxx 、Xxxxln 、Xxxxf”，基本和fmt中的相关函数类似。</p>
<h3>1. Go中的log包</h3>
<h4>1. 基本使用</h4>
<ol>
<li><u>log.Print：打印日志，和fmt包没什么区别，只是加上了上面的日志格式</u></li>
<li><u>log.Fatal ：会先将日志内容打印到标准输出，接着调用系统的os.exit(1) 接口，退出程序并返回状态 1 。但是有一点需要注意，由于是直接调用系统接口退出，defer函数不会被调用</u></li>
<li><u>log.Panic：该函数把日志内容刷到标准错误后调用 panic 函数</u></li>
</ol>
<p>log 结构的定义如下：</p>
<pre><code class="prism language-go"><span class="token keyword">type</span> Logger <span class="token keyword">struct</span> <span class="token punctuation">{</span>
mu sync<span class="token punctuation">.</span>Mutex <span class="token comment">// ensures atomic writes; protects the following fields</span>
prefix <span class="token builtin">string</span> <span class="token comment">// prefix to write at beginning of each line</span>
flag <span class="token builtin">int</span> <span class="token comment">// properties</span>
out io<span class="token punctuation">.</span>Writer<span class="token comment">// destination for output</span>
buf <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token builtin">byte</span> <span class="token comment">// for accumulating text to write</span>
<span class="token punctuation">}</span>
</code></pre>
<p>可见在结构体中有sync.Mutex类型字段，所以log中所有的操作都是支持并发的。</p>
<p>下面看一下这三种log打印的用法：</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
<span class="token string">"log"</span>
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Print</span><span class="token punctuation">(</span><span class="token string">"我就是一条日志"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"%s,"</span><span class="token punctuation">,</span><span class="token string">"谁说我是日志了，我是错误"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Panic</span><span class="token punctuation">(</span><span class="token string">"哈哈，我好痛"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre>
<p>输出：</p>
<pre><code>2019/05/23 22:14:36 我就是一条日志
2019/05/23 22:14:36 谁说我是日志了，我是错误,
2019/05/23 22:14:36 哈哈，我好痛
panic: 哈哈，我好痛
goroutine 1 :
log.Panic(0xc00007bf78, 0x1, 0x1)
D:/soft/go/src/log/log.go:333 +0xb3
main.main()
E:/go_path/src/webDemo/demo.go:12 +0xfd
</code></pre>
<p>使用非常简单，可以看到log的默认输出带了时间，非常的方便。<code>Panic</code>方法在输出后调用了<code>Panic</code>方法，所以抛出了异常信息。上面的示例中没有演示<code>Fatal</code>方法，你可以试着把<code>log.Fatal()</code>放在程序的第一行，你会发现下面的代码都不会执行。因为上面说过，它在打印完日志之后会调用<code>os.exit(1)</code>方法，所以系统就退出了。</p>
<h4>2. 定制打印参数</h4>
<p>上面说到log打印的时候默认是自带时间的，那如果除了时间以外，我们还想要别的信息呢，当然log也是支持的。</p>
<p><code>SetFlags(flag int)</code>方法提供了设置打印默认信息的能力，下面的字段是log中自带的支持的打印类型：</p>
<pre><code>Ldate = 1 << iota // the date in the local time zone: 2009/01/23
Ltime // the time in the local time zone: 01:23:23
Lmicroseconds // microsecond resolution: 01:23:23.123123.assumes Ltime.
Llongfile // full file name and line number: /a/b/c/d.go:23
Lshortfile // final file name element and line number: d.go:23. overrides Llongfile
LUTC // if Ldate or Ltime is set, use UTC rather than the local time zone
LstdFlags = Ldate | Ltime // initial values for the standard logger
</code></pre>
<p>这是log包定义的一些抬头信息，有日期、时间、毫秒时间、绝对路径和行号、文件名和行号等，在上面都有注释说明，这里需要注意的是：如果设置了<code>Lmicroseconds</code>，那么<code>Ltime</code>就不生效了；设置了<code>Lshortfile</code>， <code>Llongfile</code>也不会生效，大家自己可以测试一下。</p>
<p><code>LUTC</code>比较特殊，如果我们配置了时间标签，那么如果设置了<code>LUTC</code>的话，就会把输出的日期时间转为0时区的日期时间显示。</p>
<p>最后一个<code>LstdFlags</code>表示标准的日志抬头信息，也就是默认的，包含日期和具体时间。</p>
<p>使用方法：</p>
<pre><code class="prism language-go"><span class="token keyword">func</span> <span class="token function">init</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">SetFlags</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Ldate<span class="token operator">|</span>log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre>
<p>使用init方法，可以在main函数执行之前初始化代码。另外，虽然参数是int类型，但是上例中使用位运算符传递了多个常量为什么会被识别到底传了啥进去了呢。这是因为源码中去做解析的时候，也是根据不同的常量组合的位运算去判断你传了啥的。所以先看源码，你就可以大胆的传了。</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
<span class="token string">"log"</span>
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">SetFlags</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Ldate<span class="token operator">|</span>log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Print</span><span class="token punctuation">(</span><span class="token string">"我就是一条日志"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"%s,"</span><span class="token punctuation">,</span><span class="token string">"谁说我是日志了，我是错误"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
输出：
<span class="token number">2019</span><span class="token operator">/</span><span class="token number">05</span><span class="token operator">/</span><span class="token number">23</span> demo<span class="token punctuation">.</span><span class="token keyword">go</span><span class="token punctuation">:</span><span class="token number">11</span><span class="token punctuation">:</span> 我就是一条日志
<span class="token number">2019</span><span class="token operator">/</span><span class="token number">05</span><span class="token operator">/</span><span class="token number">23</span> demo<span class="token punctuation">.</span><span class="token keyword">go</span><span class="token punctuation">:</span><span class="token number">12</span><span class="token punctuation">:</span> 谁说我是日志了，我是错误<span class="token punctuation">,</span>
</code></pre>
<h3>3. 如何传自定义参数进日志</h3>
<p>在Java开发中我们会有这样的日志需求：为了查日志更方便，我们需要在一个http请求或者rpc请求进来到结束的作用链中用一个唯一id将所有的日志串起来，这样可以在日志中搜索这个唯一id就能拿到这次请求的所有日志记录。</p>
<p>所以现在的任务是如何在Go的日志中去定义这样的一个id。Go中提供了这样的一个方法：<code>SetPrefix(prefix string)</code>,通过<code>log.SetPrefix</code>可以指定输出日志的前缀。</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
uuid <span class="token string">"github.com/satori/go.uuid"</span>
<span class="token string">"log"</span>
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
uuids<span class="token punctuation">,</span> <span class="token boolean">_</span> <span class="token operator">:=</span> uuid<span class="token punctuation">.</span><span class="token function">NewV1</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">SetPrefix</span><span class="token punctuation">(</span>uuids<span class="token punctuation">.</span><span class="token function">String</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span><span class="token string">" "</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">SetFlags</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Ldate<span class="token operator">|</span>log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Print</span><span class="token punctuation">(</span><span class="token string">"我就是一条日志"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"%s,"</span><span class="token punctuation">,</span><span class="token string">"谁说我是日志了，我是错误"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
输出：
<span class="token number">1791</span>d770<span class="token operator">-</span><span class="token number">7</span>d6a<span class="token operator">-</span><span class="token number">11e9</span><span class="token operator">-</span>b2ee<span class="token operator">-</span><span class="token number">00</span>fffa4e4d0c <span class="token number">2019</span><span class="token operator">/</span><span class="token number">05</span><span class="token operator">/</span><span class="token number">23</span> demo<span class="token punctuation">.</span><span class="token keyword">go</span><span class="token punctuation">:</span><span class="token number">13</span><span class="token punctuation">:</span> 我就是一条日志
<span class="token number">1791</span>d770<span class="token operator">-</span><span class="token number">7</span>d6a<span class="token operator">-</span><span class="token number">11e9</span><span class="token operator">-</span>b2ee<span class="token operator">-</span><span class="token number">00</span>fffa4e4d0c <span class="token number">2019</span><span class="token operator">/</span><span class="token number">05</span><span class="token operator">/</span><span class="token number">23</span> demo<span class="token punctuation">.</span><span class="token keyword">go</span><span class="token punctuation">:</span><span class="token number">14</span><span class="token punctuation">:</span> 谁说我是日志了，我是错误<span class="token punctuation">,</span>
</code></pre>
<h4>4. log 输出的底层实现</h4>
<p>从源码中我们可以看到，无论是Print，Panic，还是Fatal他们都是使用<code>std.Output(calldepth int, s string)</code>方法。std的定义如下：</p>
<pre><code class="prism language-go"><span class="token keyword">func</span> <span class="token function">New</span><span class="token punctuation">(</span>out io<span class="token punctuation">.</span>Writer<span class="token punctuation">,</span> prefix <span class="token builtin">string</span><span class="token punctuation">,</span> flag <span class="token builtin">int</span><span class="token punctuation">)</span> <span class="token operator">*</span>Logger <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token operator">&</span>Logger<span class="token punctuation">{</span>out<span class="token punctuation">:</span> out<span class="token punctuation">,</span> prefix<span class="token punctuation">:</span> prefix<span class="token punctuation">,</span> flag<span class="token punctuation">:</span> flag<span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token keyword">var</span> std <span class="token operator">=</span> <span class="token function">New</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stderr<span class="token punctuation">,</span> <span class="token string">""</span><span class="token punctuation">,</span> LstdFlags<span class="token punctuation">)</span>
</code></pre>
<p>即每一次调用log的时候都会去创建一个Logger对象。另外New中传入的第一个参数是<code>os.Stderr</code>，<code>os.Stderr</code>对应的是UNIX里的标准错误警告信息的输出设备，同时被作为默认的日志输出目的地。初次之外，还有标准输出设备<code>os.Stdout</code>以及标准输入设备<code>os.Stdin</code>。</p>
<pre><code class="prism language-go"><span class="token keyword">var</span> <span class="token punctuation">(</span>
Stdin<span class="token operator">=</span> <span class="token function">NewFile</span><span class="token punctuation">(</span><span class="token function">uintptr</span><span class="token punctuation">(</span>syscall<span class="token punctuation">.</span>Stdin<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token string">"/dev/stdin"</span><span class="token punctuation">)</span>
Stdout <span class="token operator">=</span> <span class="token function">NewFile</span><span class="token punctuation">(</span><span class="token function">uintptr</span><span class="token punctuation">(</span>syscall<span class="token punctuation">.</span>Stdout<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token string">"/dev/stdout"</span><span class="token punctuation">)</span>
Stderr <span class="token operator">=</span> <span class="token function">NewFile</span><span class="token punctuation">(</span><span class="token function">uintptr</span><span class="token punctuation">(</span>syscall<span class="token punctuation">.</span>Stderr<span class="token punctuation">)</span><span class="token punctuation">,</span> <span class="token string">"/dev/stderr"</span><span class="token punctuation">)</span>
<span class="token punctuation">)</span>
</code></pre>
<p>前两种分别用于输入、输出和警告错误信息。</p>
<p>我们再来看一下，所有的输出都会调用的方法：<code>std.Output(calldepth int, s string)</code></p>
<pre><code class="prism language-go"><span class="token keyword">func</span> <span class="token punctuation">(</span>l <span class="token operator">*</span>Logger<span class="token punctuation">)</span> <span class="token function">Output</span><span class="token punctuation">(</span>calldepth <span class="token builtin">int</span><span class="token punctuation">,</span> s <span class="token builtin">string</span><span class="token punctuation">)</span> <span class="token builtin">error</span> <span class="token punctuation">{</span>
now <span class="token operator">:=</span> time<span class="token punctuation">.</span><span class="token function">Now</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">var</span> file <span class="token builtin">string</span>
<span class="token keyword">var</span> line <span class="token builtin">int</span>
<span class="token comment">//加锁，保证多goroutine下的安全</span>
l<span class="token punctuation">.</span>mu<span class="token punctuation">.</span><span class="token function">Lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">defer</span> l<span class="token punctuation">.</span>mu<span class="token punctuation">.</span><span class="token function">Unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token comment">//如果配置了获取文件和行号的话</span>
<span class="token keyword">if</span> l<span class="token punctuation">.</span>flag<span class="token operator">&</span><span class="token punctuation">(</span>Lshortfile<span class="token operator">|</span>Llongfile<span class="token punctuation">)</span> <span class="token operator">!=</span> <span class="token number">0</span> <span class="token punctuation">{</span>
<span class="token comment">//因为runtime.Caller代价比较大，先不加锁</span>
l<span class="token punctuation">.</span>mu<span class="token punctuation">.</span><span class="token function">Unlock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token keyword">var</span> ok <span class="token builtin">bool</span>
<span class="token boolean">_</span><span class="token punctuation">,</span> file<span class="token punctuation">,</span> line<span class="token punctuation">,</span> ok <span class="token operator">=</span> runtime<span class="token punctuation">.</span><span class="token function">Caller</span><span class="token punctuation">(</span>calldepth<span class="token punctuation">)</span>
<span class="token keyword">if</span> <span class="token operator">!</span>ok <span class="token punctuation">{</span>
file <span class="token operator">=</span> <span class="token string">"???"</span>
line <span class="token operator">=</span> <span class="token number">0</span>
<span class="token punctuation">}</span>
<span class="token comment">//获取到行号等信息后，再加锁，保证安全</span>
l<span class="token punctuation">.</span>mu<span class="token punctuation">.</span><span class="token function">Lock</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token comment">//把我们的日志信息和设置的日志抬头进行拼接</span>
l<span class="token punctuation">.</span>buf <span class="token operator">=</span> l<span class="token punctuation">.</span>buf<span class="token punctuation">[</span><span class="token punctuation">:</span><span class="token number">0</span><span class="token punctuation">]</span>
l<span class="token punctuation">.</span><span class="token function">formatHeader</span><span class="token punctuation">(</span><span class="token operator">&</span>l<span class="token punctuation">.</span>buf<span class="token punctuation">,</span> now<span class="token punctuation">,</span> file<span class="token punctuation">,</span> line<span class="token punctuation">)</span>
l<span class="token punctuation">.</span>buf <span class="token operator">=</span> <span class="token function">append</span><span class="token punctuation">(</span>l<span class="token punctuation">.</span>buf<span class="token punctuation">,</span> s<span class="token operator">...</span><span class="token punctuation">)</span>
<span class="token keyword">if</span> <span class="token function">len</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">0</span> <span class="token operator">||</span> s<span class="token punctuation">[</span><span class="token function">len</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span><span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">!=</span> <span class="token string">'\n'</span> <span class="token punctuation">{</span>
l<span class="token punctuation">.</span>buf <span class="token operator">=</span> <span class="token function">append</span><span class="token punctuation">(</span>l<span class="token punctuation">.</span>buf<span class="token punctuation">,</span> <span class="token string">'\n'</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token comment">//输出拼接好的缓冲buf里的日志信息到目的地</span>
<span class="token boolean">_</span><span class="token punctuation">,</span> err <span class="token operator">:=</span> l<span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">Write</span><span class="token punctuation">(</span>l<span class="token punctuation">.</span>buf<span class="token punctuation">)</span>
<span class="token keyword">return</span> err
<span class="token punctuation">}</span>
</code></pre>
<p><code>formatHeader</code>方法主要是格式化日志抬头信息，就是我们上面提到设置的日志打印格式，解析完之后存储在<code>buf</code>这个缓冲中，最后再把我们自己的日志信息拼接到缓冲<code>buf</code>的后面，然后为一次log日志输出追加一个换行符，这样每次日志输出都是一行一行的。</p>
<p>上面我们提到过<code>runtime.Caller(calldepth)</code>这个方法，runtime包非常有意思，后面也会去说，他提供了一个运行时环境，可以在运行时去管理内存分配，垃圾回收，时间片切换等等，类似于Java中虚拟机做的活。（是不是很疑惑为什么在Go中竟然可以去做Java中虚拟机能做的事情，其实想想协程的概念，再对比线程的概念，就不会疑惑为啥会给你提供这么个包）。</p>
<p>Caller方法的解释是：</p>
<blockquote>
<p>Caller方法查询有关函数调用的文件和行号信息，通过调用Goroutine的堆栈。参数skip是堆栈帧框架升序方式排列的数字值，0标识Caller方法的调用。（出于历史原因，Skip的含义在调用者和调用者之间有所不同。）</p>
<p>返回值报告程序计数器、文件名和相应文件中行号的查询。如果无法恢复信息，则Boolean OK为 fasle。</p>
</blockquote>
<p>Caller方法的定义：</p>
<pre><code class="prism language-go"><span class="token keyword">func</span> <span class="token function">Caller</span><span class="token punctuation">(</span>skip <span class="token builtin">int</span><span class="token punctuation">)</span> <span class="token punctuation">(</span>pc <span class="token builtin">uintptr</span><span class="token punctuation">,</span> file <span class="token builtin">string</span><span class="token punctuation">,</span> line <span class="token builtin">int</span><span class="token punctuation">,</span> ok <span class="token builtin">bool</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token punctuation">}</span>
</code></pre>
<p>参数<code>skip</code>表示跳过栈帧数，<code>0</code>表示不跳过，也就是<code>runtime.Caller</code>的调用者。<code>1</code>的话就是再向上一层，表示调用者的调用者。</p>
<p>log日志包里使用的是<code>2</code>，也就是表示我们在源代码中调用<code>log.Print</code>、<code>log.Fatal</code>和<code>log.Panic</code>这些函数的调用者。</p>
<p>以<code>main</code>函数调用<code>log.Println</code>为例，<code>main->log.Println->*Logger.Output->runtime.Caller</code>这么一个方法调用栈，所以这时候，skip的值分别代表：</p>
<ol>
<li><code>0</code>表示<code>*Logger.Output</code>中调用<code>runtime.Caller</code>的源代码文件和行号</li>
<li><code>1</code>表示<code>log.Println</code>中调用<code>*Logger.Output</code>的源代码文件和行号</li>
<li><code>2</code>表示<code>main</code>中调用<code>log.Println</code>的源代码文件和行号</li>
</ol>
<p>所以这也是<code>log</code>包里的这个<code>skip</code>的值为什么一直是<code>2</code>的原因。</p>
<h4>5. 如何自定义自己的日志框架</h4>
<p>通过上面的学习，你其实知道了，日志的实现是通过New()函数构造了Logger对象来处理的。那我们只用构造不同的Logger对象来处理不同类型的日记即可。下面是一个简单的实现：</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
<span class="token string">"io"</span>
<span class="token string">"log"</span>
<span class="token string">"os"</span>
<span class="token punctuation">)</span>
<span class="token keyword">var</span> <span class="token punctuation">(</span>
Info <span class="token operator">*</span>log<span class="token punctuation">.</span>Logger
Warning <span class="token operator">*</span>log<span class="token punctuation">.</span>Logger
Error <span class="token operator">*</span> log<span class="token punctuation">.</span>Logger
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">init</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
infoFile<span class="token punctuation">,</span>err<span class="token operator">:=</span>os<span class="token punctuation">.</span><span class="token function">OpenFile</span><span class="token punctuation">(</span><span class="token string">"/data/service_logs/info.log"</span><span class="token punctuation">,</span>os<span class="token punctuation">.</span>O_CREATE<span class="token operator">|</span>os<span class="token punctuation">.</span>O_WRONLY<span class="token operator">|</span>os<span class="token punctuation">.</span>O_APPEND<span class="token punctuation">,</span><span class="token number">0666</span><span class="token punctuation">)</span>
warnFile<span class="token punctuation">,</span>err<span class="token operator">:=</span>os<span class="token punctuation">.</span><span class="token function">OpenFile</span><span class="token punctuation">(</span><span class="token string">"/data/service_logs/warn.log"</span><span class="token punctuation">,</span>os<span class="token punctuation">.</span>O_CREATE<span class="token operator">|</span>os<span class="token punctuation">.</span>O_WRONLY<span class="token operator">|</span>os<span class="token punctuation">.</span>O_APPEND<span class="token punctuation">,</span><span class="token number">0666</span><span class="token punctuation">)</span>
errFile<span class="token punctuation">,</span>err<span class="token operator">:=</span>os<span class="token punctuation">.</span><span class="token function">OpenFile</span><span class="token punctuation">(</span><span class="token string">"/data/service_logs/errors.log"</span><span class="token punctuation">,</span>os<span class="token punctuation">.</span>O_CREATE<span class="token operator">|</span>os<span class="token punctuation">.</span>O_WRONLY<span class="token operator">|</span>os<span class="token punctuation">.</span>O_APPEND<span class="token punctuation">,</span><span class="token number">0666</span><span class="token punctuation">)</span>
<span class="token keyword">if</span> infoFile<span class="token operator">!=</span><span class="token boolean">nil</span> <span class="token operator">||</span> warnFile <span class="token operator">!=</span> <span class="token boolean">nil</span> <span class="token operator">||</span> err<span class="token operator">!=</span><span class="token boolean">nil</span><span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Fatalln</span><span class="token punctuation">(</span><span class="token string">"打开日志文件失败："</span><span class="token punctuation">,</span>err<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
Info <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stdout<span class="token punctuation">,</span><span class="token string">"Info:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
Warning <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stdout<span class="token punctuation">,</span><span class="token string">"Warning:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
Error <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>io<span class="token punctuation">.</span><span class="token function">MultiWriter</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stderr<span class="token punctuation">,</span>errFile<span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token string">"Error:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
Info <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>io<span class="token punctuation">.</span><span class="token function">MultiWriter</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stderr<span class="token punctuation">,</span>infoFile<span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token string">"Info:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
Warning <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>io<span class="token punctuation">.</span><span class="token function">MultiWriter</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stderr<span class="token punctuation">,</span>warnFile<span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token string">"Warning:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
Error <span class="token operator">=</span> log<span class="token punctuation">.</span><span class="token function">New</span><span class="token punctuation">(</span>io<span class="token punctuation">.</span><span class="token function">MultiWriter</span><span class="token punctuation">(</span>os<span class="token punctuation">.</span>Stderr<span class="token punctuation">,</span>errFile<span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token string">"Error:"</span><span class="token punctuation">,</span>log<span class="token punctuation">.</span>Ldate <span class="token operator">|</span> log<span class="token punctuation">.</span>Ltime <span class="token operator">|</span> log<span class="token punctuation">.</span>Lshortfile<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
Info<span class="token punctuation">.</span><span class="token function">Println</span><span class="token punctuation">(</span><span class="token string">"我就是一条日志啊"</span><span class="token punctuation">)</span>
Warning<span class="token punctuation">.</span><span class="token function">Printf</span><span class="token punctuation">(</span><span class="token string">"我真的是一条日志哟%s\n"</span><span class="token punctuation">,</span><span class="token string">"别骗我"</span><span class="token punctuation">)</span>
Error<span class="token punctuation">.</span><span class="token function">Println</span><span class="token punctuation">(</span><span class="token string">"好了，我要报错了"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre>
<h3>2. 第三方日志包logrus</h3>
<p>上面介绍了Go中的log包，Go标准库的日志框架非常简单，仅仅提供了Print，Panic和Fatal三个函数。对于更精细的日志级别、日志文件分割，以及日志分发等方面，并没有提供支持 。也有很多第三方的开源爱好者贡献了很多好用的日志框架，毕竟Go是新兴预言，目前为止没有哪个日志框架能产生与Java中的slf4j一样的地位，目前流行的日志框架有seelog，zap，logrus，还有beego中的日志框架部分。</p>
<p>这些日志框架可能在某些方面不能满足你的需求，所以使用之前先了解清楚。因为logrus目前在GitHub上的star最高，11011。所以本篇文章介绍logrus的使用，大家可以举一反三。 logrus的GitHub地址:</p>
<h4>1. logrus特性</h4>
<p>logrus支持如下特性：</p>
<ol>
<li>完全兼容Go标准库日志模块。logrus拥有六种日志级别：debug、info、warn、error、fatal和panic，这是Go标准库日志模块的API的超集。如果你的项目使用标准库日志模块，完全可以用最低的代价迁移到logrus上。</li>
<li>可扩展的Hook机制。允许使用者通过hook方式，将日志分发到任意地方，如本地文件系统、标准输出、logstash、elasticsearch或者mq等，或者通过hook定义日志内容和格式等。</li>
<li>可选的日志输出格式。**logrus内置了两种日志格式，JSONFormatter和TextFormatter。**如果这两个格式不满足需求，可以自己动手实现接口Formatter，来定义自己的日志格式。</li>
<li>Field机制。logrus鼓励通过Field机制进行精细化、结构化的日志记录，而不是通过冗长的消息来记录日志。</li>
<li>logrus是一个可插拔的、结构化的日志框架。</li>
</ol>
<p>logrus不提供的功能：</p>
<ol>
<li>没有提供行号和文件名的支持</li>
<li>输出到本地文件系统没有提供日志分割功能</li>
<li>没有提供输出到ELK等日志处理中心的功能</li>
</ol>
<p>这些功能都可以通过自定义hook来实现 。</p>
<h4>2. 简单的入门</h4>
<p>安装：</p>
<pre><code>go get github.com/sirupsen/logrus
</code></pre>
<h5>2.1 一个简单的入门：</h5>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> log <span class="token string">"github.com/sirupsen/logrus"</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
log<span class="token punctuation">.</span><span class="token function">Info</span><span class="token punctuation">(</span><span class="token string">"我是一条日志"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span><span class="token string">"key"</span><span class="token punctuation">:</span><span class="token string">"value"</span><span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Info</span><span class="token punctuation">(</span><span class="token string">"我要打印了"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
输出：
time<span class="token operator">=</span><span class="token string">"2019-05-24T08:13:47+08:00"</span> level<span class="token operator">=</span>info msg<span class="token operator">=</span><span class="token string">"我是一条日志"</span>
time<span class="token operator">=</span><span class="token string">"2019-05-24T08:13:47+08:00"</span> level<span class="token operator">=</span>info msg<span class="token operator">=</span><span class="token string">"我要打印了"</span> key<span class="token operator">=</span>value
</code></pre>
<h5>2.2 设置log的日志输出为json格式</h5>
<p>将日志输出格式设置为JSON格式：</p>
<pre><code class="prism language-go">log<span class="token punctuation">.</span><span class="token function">SetFormatter</span><span class="token punctuation">(</span><span class="token operator">&</span>log<span class="token punctuation">.</span>JSONFormatter<span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>
</code></pre>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
log <span class="token string">"github.com/sirupsen/logrus"</span>
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">initLog</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token comment">// 设置日志格式为json格式</span>
log<span class="token punctuation">.</span><span class="token function">SetFormatter</span><span class="token punctuation">(</span><span class="token operator">&</span>log<span class="token punctuation">.</span>JSONFormatter<span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token function">initLog</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">12</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaoming"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Info</span><span class="token punctuation">(</span><span class="token string">"小明来了"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">13</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaohong"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Error</span><span class="token punctuation">(</span><span class="token string">"小红来了"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">14</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaofang"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span><span class="token string">"小芳来了"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
输出：
<span class="token punctuation">{</span><span class="token string">"age"</span><span class="token punctuation">:</span><span class="token number">12</span><span class="token punctuation">,</span><span class="token string">"level"</span><span class="token punctuation">:</span><span class="token string">"info"</span><span class="token punctuation">,</span><span class="token string">"msg"</span><span class="token punctuation">:</span><span class="token string">"小明来了"</span><span class="token punctuation">,</span><span class="token string">"name"</span><span class="token punctuation">:</span><span class="token string">"xiaoming"</span><span class="token punctuation">,</span><span class="token string">"sex"</span><span class="token punctuation">:</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token string">"time"</span><span class="token punctuation">:</span><span class="token string">"2019-05-24T08:20:19+08:00"</span><span class="token punctuation">}</span>
<span class="token punctuation">{</span><span class="token string">"age"</span><span class="token punctuation">:</span><span class="token number">13</span><span class="token punctuation">,</span><span class="token string">"level"</span><span class="token punctuation">:</span><span class="token string">"error"</span><span class="token punctuation">,</span><span class="token string">"msg"</span><span class="token punctuation">:</span><span class="token string">"小红来了"</span><span class="token punctuation">,</span><span class="token string">"name"</span><span class="token punctuation">:</span><span class="token string">"xiaohong"</span><span class="token punctuation">,</span><span class="token string">"sex"</span><span class="token punctuation">:</span><span class="token number">0</span><span class="token punctuation">,</span><span class="token string">"time"</span><span class="token punctuation">:</span><span class="token string">"2019-05-24T08:20:19+08:00"</span><span class="token punctuation">}</span>
<span class="token punctuation">{</span><span class="token string">"age"</span><span class="token punctuation">:</span><span class="token number">14</span><span class="token punctuation">,</span><span class="token string">"level"</span><span class="token punctuation">:</span><span class="token string">"fatal"</span><span class="token punctuation">,</span><span class="token string">"msg"</span><span class="token punctuation">:</span><span class="token string">"小芳来了"</span><span class="token punctuation">,</span><span class="token string">"name"</span><span class="token punctuation">:</span><span class="token string">"xiaofang"</span><span class="token punctuation">,</span><span class="token string">"sex"</span><span class="token punctuation">:</span><span class="token number">1</span><span class="token punctuation">,</span><span class="token string">"time"</span><span class="token punctuation">:</span><span class="token string">"2019-05-24T08:20:19+08:00"</span><span class="token punctuation">}</span>
</code></pre>
<p>看到这里输出的日志格式与上面的区别，这里是json格式，上面是纯文本。</p>
<h5>2.3 设置日志打印级别</h5>
<p>logrus 提供 6 档日志级别，分别是：</p>
<pre><code>PanicLevel
FatalLevel
ErrorLevel
WarnLevel
InfoLevel
DebugLevel
</code></pre>
<p>设置日志输出级别：</p>
<pre><code class="prism language-go">log<span class="token punctuation">.</span><span class="token function">SetLevel</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>WarnLevel<span class="token punctuation">)</span>
</code></pre>
<h5>2.4 自定义输出字段</h5>
<p>logrus 默认的日志输出有 time、level 和 msg 3个 Field，其中 time 可以不显示，方法如下：</p>
<pre><code>log.SetFormatter(&log.TextFormatter{DisableTimestamp: true})
</code></pre>
<p>自定义 Field 的方法如下：</p>
<pre><code class="prism language-go">log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">14</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaofang"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span><span class="token string">"小芳来了"</span><span class="token punctuation">)</span>
</code></pre>
<h5>2.5 自定义日志输出路径</h5>
<p>logrus默认日志输出为stderr，你可以修改为任何的io.Writer。比如os.File文件流。</p>
<pre><code class="prism language-go"><span class="token keyword">func</span> <span class="token function">init</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token comment">//设置输出样式，自带的只有两种样式logrus.JSONFormatter{}和logrus.TextFormatter{}</span>
logrus<span class="token punctuation">.</span><span class="token function">SetFormatter</span><span class="token punctuation">(</span><span class="token operator">&</span>logrus<span class="token punctuation">.</span>JSONFormatter<span class="token punctuation">{</span><span class="token punctuation">}</span><span class="token punctuation">)</span>
<span class="token comment">//设置output,默认为stderr,可以为任何io.Writer，比如文件*os.File</span>
file<span class="token punctuation">,</span> <span class="token boolean">_</span> <span class="token operator">:=</span> os<span class="token punctuation">.</span><span class="token function">OpenFile</span><span class="token punctuation">(</span><span class="token string">"1.log"</span><span class="token punctuation">,</span> os<span class="token punctuation">.</span>O_CREATE<span class="token operator">|</span>os<span class="token punctuation">.</span>O_WRONLY<span class="token punctuation">,</span> <span class="token number">0666</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">SetOutput</span><span class="token punctuation">(</span>file<span class="token punctuation">)</span>
<span class="token comment">//设置最低loglevel</span>
logrus<span class="token punctuation">.</span><span class="token function">SetLevel</span><span class="token punctuation">(</span>logrus<span class="token punctuation">.</span>InfoLevel<span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre>
<h4>3. 高级功能-hook机制</h4>
<p>上面说过logrus是一个支持可插拔，结构化的日志框架，可插拔的特性就在于它的hook机制。一些功能需要用户自己通过hook机制去实现定制化的开发。比如说在log4j中常见的日志按天按小时做切分的功能官方并没有提供支持，你可以通过hook机制实现它。</p>
<p>Hook接口定义如下：</p>
<pre><code class="prism language-go"><span class="token keyword">type</span> Hook <span class="token keyword">interface</span> <span class="token punctuation">{</span>
<span class="token function">Levels</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">[</span><span class="token punctuation">]</span>Level
<span class="token function">Fire</span><span class="token punctuation">(</span><span class="token operator">*</span>Entry<span class="token punctuation">)</span> <span class="token builtin">error</span>
<span class="token punctuation">}</span>
</code></pre>
<p>logrus的hook原理是：在每次写入日志时拦截，修改logrus.Entry 。logrus在记录Levels()返回的日志级别的消息时，会触发HOOK， 然后按照Fire方法定义的内容，修改logrus.Entry 。logrus.Entry里面就是记录的每一条日志的内容。</p>
<p>所以在Hook中你需要做的就是在Fire方法中定义你想如何操作这一条日志的方法，在Levels方法中定义你想展示的日志级别。</p>
<p>如下是一个在所有日志中打印一个特殊字符串的Hook：</p>
<p>TraceIdHook</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> hook
<span class="token keyword">import</span> <span class="token punctuation">(</span>
<span class="token string">"github.com/sirupsen/logrus"</span>
<span class="token punctuation">)</span>
<span class="token keyword">type</span> TraceIdHook <span class="token keyword">struct</span> <span class="token punctuation">{</span>
TraceId<span class="token builtin">string</span>
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token function">NewTraceIdHook</span><span class="token punctuation">(</span>traceId <span class="token builtin">string</span><span class="token punctuation">)</span> logrus<span class="token punctuation">.</span>Hook <span class="token punctuation">{</span>
hook <span class="token operator">:=</span> TraceIdHook<span class="token punctuation">{</span>
TraceId<span class="token punctuation">:</span>traceId<span class="token punctuation">,</span>
<span class="token punctuation">}</span>
<span class="token keyword">return</span> <span class="token operator">&</span>hook
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token punctuation">(</span>hook <span class="token operator">*</span>TraceIdHook<span class="token punctuation">)</span> <span class="token function">Fire</span><span class="token punctuation">(</span>entry <span class="token operator">*</span>logrus<span class="token punctuation">.</span>Entry<span class="token punctuation">)</span> <span class="token builtin">error</span> <span class="token punctuation">{</span>
entry<span class="token punctuation">.</span>Data<span class="token punctuation">[</span><span class="token string">"traceId"</span><span class="token punctuation">]</span> <span class="token operator">=</span> hook<span class="token punctuation">.</span>TraceId
<span class="token keyword">return</span> <span class="token boolean">nil</span>
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token punctuation">(</span>hook <span class="token operator">*</span>TraceIdHook<span class="token punctuation">)</span> <span class="token function">Levels</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">[</span><span class="token punctuation">]</span>logrus<span class="token punctuation">.</span>Level <span class="token punctuation">{</span>
<span class="token keyword">return</span> logrus<span class="token punctuation">.</span>AllLevels
<span class="token punctuation">}</span>
</code></pre>
<p>主程序：</p>
<pre><code class="prism language-go"><span class="token keyword">package</span> main
<span class="token keyword">import</span> <span class="token punctuation">(</span>
uuid <span class="token string">"github.com/satori/go.uuid"</span>
log <span class="token string">"github.com/sirupsen/logrus"</span>
<span class="token string">"webDemo/hook"</span>
<span class="token punctuation">)</span>
<span class="token keyword">func</span> <span class="token function">initLog</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
uuids<span class="token punctuation">,</span> <span class="token boolean">_</span> <span class="token operator">:=</span> uuid<span class="token punctuation">.</span><span class="token function">NewV1</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">AddHook</span><span class="token punctuation">(</span>hook<span class="token punctuation">.</span><span class="token function">NewTraceIdHook</span><span class="token punctuation">(</span>uuids<span class="token punctuation">.</span><span class="token function">String</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span><span class="token string">" "</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
<span class="token keyword">func</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token function">initLog</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">12</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaoming"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Info</span><span class="token punctuation">(</span><span class="token string">"小明来了"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">13</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaohong"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">0</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Error</span><span class="token punctuation">(</span><span class="token string">"小红来了"</span><span class="token punctuation">)</span>
log<span class="token punctuation">.</span><span class="token function">WithFields</span><span class="token punctuation">(</span>log<span class="token punctuation">.</span>Fields<span class="token punctuation">{</span>
<span class="token string">"age"</span><span class="token punctuation">:</span> <span class="token number">14</span><span class="token punctuation">,</span>
<span class="token string">"name"</span><span class="token punctuation">:</span> <span class="token string">"xiaofang"</span><span class="token punctuation">,</span>
<span class="token string">"sex"</span><span class="token punctuation">:</span> <span class="token number">1</span><span class="token punctuation">,</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">Fatal</span><span class="token punctuation">(</span><span class="token string">"小芳来了"</span><span class="token punctuation">)</span>
<span class="token punctuation">}</span>
</code></pre>
<p>该hook会在日志中打印出一个uuid字符串。</p><br><br>
来源：https://www.cnblogs.com/rickiyang/p/11074164.html
頁:
[1]