实例讲解Springboot整合MongoDB进行CRUD操作的两种方式
<h1 id="1-简介">1 简介</h1><p><code>Springboot</code>是最简单的使用<code>Spring</code>的方式，而<code>MongoDB</code>是最流行的<code>NoSQL</code>数据库。两者在分布式、微服务架构中使用率极高，本文将用实例介绍如何在<code>Springboot</code>中整合<code>MongoDB</code>的两种方法：<code>MongoRepository</code>和<code>MongoTemplate</code>。</p>
<p>代码结构如下：</p>
<p><img src="https://img2020.cnblogs.com/other/946674/202004/946674-20200420070100797-1205459233.jpg"></p>
<h1 id="2-项目准备">2 项目准备</h1>
<h2 id="21-启动mongodb实例">2.1 启动MongoDB实例</h2>
<p>为了方便，使用<code>Docker</code>来启动<code>MongoDB</code>，详细指导文档请参考：用Docker安装一个MongoDB最新版玩玩 ，这里不再赘述。</p>
<h2 id="22-引入相关依赖">2.2 引入相关依赖</h2>
<p>主要的依赖为<code>Web</code>和<code>MongoDB</code>的<code>starter</code>，把下面代码加入到<code>pom.xml</code>中即可：</p>
<pre><code class="language-xml"><dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</code></pre>
<h2 id="23-配置数据库连接信息">2.3 配置数据库连接信息</h2>
<p>与配置<code>MySQL</code>或<code>Oracle</code>一样，<code>MongoDB</code>也需要配置连接信息，配置在<code>application.properties</code>中如下：</p>
<pre><code class="language-properties">server.port=8080
spring.data.mongodb.authentication-database=admin
spring.data.mongodb.database=testdb
spring.data.mongodb.username=user
spring.data.mongodb.password=123456
spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
</code></pre>
<h2 id="24-创建数据模型实体">2.4 创建数据模型实体</h2>
<p>创建<code>User</code>类如下：</p>
<pre><code class="language-java">package com.pkslow.mongo.model;
import org.springframework.data.annotation.Id;
import java.util.Date;
public class User {
@Id
private String userId;
private String name;
private Integer age;
private Date createTime = new Date();
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public Date getCreateTime() {
return createTime;
}
public void setCreateTime(Date createTime) {
this.createTime = createTime;
}
}
</code></pre>
<p>不需要在<code>MongoDB</code>中创建对应的<code>Collections</code>（表），当通过Web应用新增时会自动创建。</p>
<h1 id="3-方式1mongorepository">3 方式1：MongoRepository</h1>
<h2 id="31-定义数据访问层userrepository">3.1 定义数据访问层UserRepository</h2>
<p>使用过<code>Spring Jpa</code>的都清楚，<code>Repository</code>实际就是用于操作数据库的类。在非关系型数据库<code>MongoDB</code>的整合中，也是一样的。<code>Spring</code>会帮我们实现好对应接口的方法，开发人员连<code>SQL</code>都不用写，非常省心。代码如下：</p>
<pre><code class="language-java">package com.pkslow.mongo.dal;
import com.pkslow.mongo.model.User;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface UserRepository extends MongoRepository<User, String> {
}
</code></pre>
<p>注意<code>MongoRepository</code>后面接的泛型<code><User, String></code>第一个为实体类，第二个为主键<code>ID</code>。</p>
<h2 id="32-实现controller">3.2 实现Controller</h2>
<p><code>Controller</code>比较基础，就不讲解了，常用的注解是必须要掌握的，直接上代码吧：</p>
<pre><code class="language-java">package com.pkslow.mongo.contrlloer;
import com.pkslow.mongo.dal.UserRepository;
import com.pkslow.mongo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/user")
public class UserController {
@Autowired
private final UserRepository userRepository;
public UserController(UserRepository userRepository) {
this.userRepository = userRepository;
}
@GetMapping("")
public List<User> getAllUsers() {
return userRepository.findAll();
}
@GetMapping("/{userId}")
public User getByUserId(@PathVariable String userId) {
return userRepository.findById(userId).orElse(new User());
}
@PostMapping("")
public User addNewUser(@RequestBody User user) {
return userRepository.save(user);
}
@DeleteMapping("/{userId}")
public String delete(@PathVariable String userId) {
User user = new User();
user.setUserId(userId);
userRepository.deleteById(userId);
return "deleted: " + userId;
}
@PutMapping("")
public User update(@RequestBody User user) {
return userRepository.save(user);
}
}
</code></pre>
<p>注意代码没有做异常情况的判断和处理，这里为了快速演示，就先不管了。</p>
<h2 id="33-测试">3.3 测试</h2>
<p>用<code>Postman</code>测试后，每个接口均调用成功。就不一一截图了。</p>
<p><img src="https://img2020.cnblogs.com/other/946674/202004/946674-20200420070105430-429822646.jpg"></p>
<h1 id="4-方式2mongotemplate">4 方式2：MongoTemplate</h1>
<h2 id="41-定义数据访问层userdal">4.1 定义数据访问层UserDAL</h2>
<p>先定义接口为：</p>
<pre><code class="language-java">package com.pkslow.mongo.dal;
import com.pkslow.mongo.model.User;
import java.util.List;
public interface UserDAL {
List<User> findAll();
User findById(String userId);
User save(User user);
void deleteById(String userId);
}
</code></pre>
<p>然后实现该接口如下：</p>
<pre><code class="language-java">package com.pkslow.mongo.dal;
import com.pkslow.mongo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.stereotype.Repository;
import java.util.List;
@Repository
public class UserDALImpl implements UserDAL {
@Autowired
private MongoTemplate template;
@Override
public List<User> findAll() {
return template.findAll(User.class);
}
@Override
public User findById(String userId) {
return template.findById(userId,User.class);
}
@Override
public User save(User user) {
return template.save(user);
}
@Override
public void deleteById(String userId) {
Query query = new Query();
query.addCriteria(Criteria.where("userId").is(userId));
template.remove(query, User.class);
}
}
</code></pre>
<h2 id="42-实现另一个controller">4.2 实现另一个Controller</h2>
<p>这个<code>Controller</code>的代码与之前的基本一样，只是数据访问类不一样，代码如下：</p>
<pre><code class="language-java">package com.pkslow.mongo.contrlloer;
import com.pkslow.mongo.dal.UserDAL;
import com.pkslow.mongo.model.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
@RestController
@RequestMapping("/userTemplate")
public class UserTemplateController {
@Autowired
private final UserDAL userDAL;
public UserTemplateController(UserDAL userDAL) {
this.userDAL = userDAL;
}
@GetMapping("")
public List<User> getAllUsers() {
return userDAL.findAll();
}
@GetMapping("/{userId}")
public User getByUserId(@PathVariable String userId) {
return userDAL.findById(userId);
}
@PostMapping("")
public User addNewUser(@RequestBody User user) {
return userDAL.save(user);
}
@DeleteMapping("/{userId}")
public String delete(@PathVariable String userId) {
User user = new User();
user.setUserId(userId);
userDAL.deleteById(userId);
return "deleted: " + userId;
}
@PutMapping("")
public User update(@RequestBody User user) {
return userDAL.save(user);
}
}
</code></pre>
<h2 id="43-测试">4.3 测试</h2>
<p>测试一样也是全部通过：</p>
<p><img src="https://img2020.cnblogs.com/other/946674/202004/946674-20200420070105920-1580427006.jpg"></p>
<h1 id="5-总结">5 总结</h1>
<p>本文通过实例讲解了如何整合<code>Springboot</code>和<code>MongoDB</code>，主要有两种方法：<code>MongoRepository</code>和<code>MongoTemplate</code>。代码基本在文章中已经贴出来了，如果还不清楚，可以在<strong>南瓜慢说</strong>公众号回复<<strong>SpringbootMongoDB</strong>>获取代码。</p>
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来源：https://www.cnblogs.com/larrydpk/p/12735620.html
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