Node.js之文件下载
<p>Node.js之文件下载，主要最近解决我的一个需求。</p><p>需求描述:<br>如何将腾讯云上传的文件存储到本地某个目录下，如果用js来实现，纯JavaScript没有这样的功能(也许有)，正好我这个项目用node.js比较多，正好可以利用node.js丰富的API实现该功能。</p>
<p>
如下示例代码，演示下载远程文件:<br><br>源码如下(download.js):</p>
<div class="cnblogs_code">
<pre><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">下载参数</span>
<span style="color: rgba(0, 0, 255, 1)">var</span> http = require(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">http</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> fs = require(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">fs</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> path = require(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">path</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> downFlag = <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">;
</span><span style="color: rgba(0, 0, 255, 1)">var</span> downUrl = <span style="color: rgba(128, 0, 0, 1)">''</span><span style="color: rgba(0, 0, 0, 1)">;
</span><span style="color: rgba(0, 0, 255, 1)">var</span> downFileName = <span style="color: rgba(128, 0, 0, 1)">''</span><span style="color: rgba(0, 0, 0, 1)">;
</span><span style="color: rgba(0, 128, 0, 1)">/*</span><span style="color: rgba(0, 128, 0, 1)">*
* 下载回调
</span><span style="color: rgba(0, 128, 0, 1)">*/</span><span style="color: rgba(0, 0, 0, 1)">
function getHttpReqCallback (imgSrc, dirName, fileName) {
</span><span style="color: rgba(0, 0, 255, 1)">var</span> callback =<span style="color: rgba(0, 0, 0, 1)"> function(res) {
console.log(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">request: </span><span style="color: rgba(128, 0, 0, 1)">"</span> + imgSrc + <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)"> return status: </span><span style="color: rgba(128, 0, 0, 1)">"</span> +<span style="color: rgba(0, 0, 0, 1)"> res.statusCode);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> contentLength = parseInt(res.headers[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">content-length</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">]);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> downLength = <span style="color: rgba(128, 0, 128, 1)">0</span><span style="color: rgba(0, 0, 0, 1)">;
</span><span style="color: rgba(0, 0, 255, 1)">var</span> <span style="color: rgba(0, 0, 255, 1)">out</span> = fs.createWriteStream(dirName + <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">/</span><span style="color: rgba(128, 0, 0, 1)">"</span> +<span style="color: rgba(0, 0, 0, 1)"> fileName);
res.on(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">data</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">, function (chunk) {
downLength </span>+=<span style="color: rgba(0, 0, 0, 1)"> chunk.length;
</span><span style="color: rgba(0, 0, 255, 1)">var</span> progress =Math.floor(downLength*<span style="color: rgba(128, 0, 128, 1)">100</span> /<span style="color: rgba(0, 0, 0, 1)"> contentLength);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> str = <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">下载：</span><span style="color: rgba(128, 0, 0, 1)">"</span>+ progress +<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">%</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">;
console.log(str);
</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">写文件</span>
<span style="color: rgba(0, 0, 255, 1)">out</span><span style="color: rgba(0, 0, 0, 1)">.write(chunk, function () {
</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">console.log(chunk.length);</span>
<span style="color: rgba(0, 0, 0, 1)">
});
});
res.on(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">end</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">, function() {
downFlag </span>= <span style="color: rgba(0, 0, 255, 1)">false</span><span style="color: rgba(0, 0, 0, 1)">;
console.log(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">end downloading </span><span style="color: rgba(128, 0, 0, 1)">"</span> +<span style="color: rgba(0, 0, 0, 1)"> imgSrc);
</span><span style="color: rgba(0, 0, 255, 1)">if</span><span style="color: rgba(0, 0, 0, 1)"> (isNaN(contentLength)) {
console.log(imgSrc </span>+ <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)"> content length error</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)">;
}
</span><span style="color: rgba(0, 0, 255, 1)">if</span> (downLength <<span style="color: rgba(0, 0, 0, 1)"> contentLength) {
console.log(imgSrc </span>+ <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)"> download error, try again</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)">;
}
});
};
</span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> callback;
}
</span><span style="color: rgba(0, 128, 0, 1)">/*</span><span style="color: rgba(0, 128, 0, 1)">*
* 下载开始
</span><span style="color: rgba(0, 128, 0, 1)">*/</span><span style="color: rgba(0, 0, 0, 1)">
function startDownloadTask (imgSrc, dirName,fileName) {
console.log(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">start downloading </span><span style="color: rgba(128, 0, 0, 1)">"</span> +<span style="color: rgba(0, 0, 0, 1)"> imgSrc);
</span><span style="color: rgba(0, 0, 255, 1)">var</span> req =<span style="color: rgba(0, 0, 0, 1)"> http.request(imgSrc, getHttpReqCallback(imgSrc, dirName, fileName));
req.on(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">error</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">, function(e){
console.log(</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">request </span><span style="color: rgba(128, 0, 0, 1)">"</span> + imgSrc + <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)"> error, try again</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">);
});
req.end();
}
startDownloadTask(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">http://mirrors.tuna.tsinghua.edu.cn/apache/tomcat/tomcat-8/v8.5.41/bin/apache-tomcat-8.5.41.tar.gz</span><span style="color: rgba(128, 0, 0, 1)">'</span>,<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">D://1024Workspace//extension</span><span style="color: rgba(128, 0, 0, 1)">'</span>,<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">apache-tomcat-8.5.41.tar.gz</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">);
</span><span style="color: rgba(0, 128, 0, 1)">//</span><span style="color: rgba(0, 128, 0, 1)">startDownloadTask('下载地址','本地存储路径','文件名');</span></pre>
</div>
<p>代码经过测试，没有问题。</p>
<p>本文主要参考资料如下:<br>Node.js文件下载</p><br><br>
来源：https://www.cnblogs.com/youcong/p/10957880.html
頁:
[1]