MongoDB Java操作实例

###1、Maven项目创建
在~/bigdata下创建空文件夹mongodb后作为我们的项目目录(或其他指定文件夹),切换到项目目录：
```
cd ~/bigdata
mkdir mongodb
cd mongodb
```
在该目录下使用maven命令创建一个示例项目:

```
nbu@ecs:~/bigdata/mongodb$ mvn archetype:generate -DgroupId=org.nbubigdata.mongodb -DartifactId=mongodb_java -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
```
项目结构如下
![](https://hexo-img.obs.cn-east-3.myhuaweicloud.com/img/202404292045642.png)

###2、POM添加mongodb相关依赖
```
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>commons-io</groupId>
      <artifactId>commons-io</artifactId>
      <version>2.11.0</version>
    </dependency>
    <dependency>
      <groupId>org.mongodb</groupId>
      <artifactId>mongodb-driver-sync</artifactId>
      <version>4.0.5</version>
    </dependency>
  </dependencies>

<build>
    <plugins>
      <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-assembly-plugin</artifactId>
          <version>3.3.0</version>
          <configuration>
            <archive>
              <manifest>
                <addClasspath>true</addClasspath>
                <classpathPrefix>lib/</classpathPrefix>
                <mainClass>org.nbubigdata.mongodb.App</mainClass>
              </manifest>
            </archive>
            <descriptorRefs>
              <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
          </configuration>
          <executions>
            <execution>
              <id>make-assembly</id>
              <phase>package</phase>
              <goals>
                <goal>single</goal>
              </goals>
            </execution>
          </executions>
        </plugin>
    </plugins>    
  </build>
</project>
```
###3、启动MongoDB数据库
>sudo systemctl start mongodb

###4、使用Java 操作mongodb实现增删改查
```
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoClient;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.MongoCollection;
import org.bson.Document;

public class MongoDBExample {
    public static void main(String[] args) {
        // 连接到 MongoDB 服务器
        MongoClient mongoClient = MongoClients.create("mongodb://localhost:27017");

// 连接到数据库
        MongoDatabase database = mongoClient.getDatabase("mydb");

// 获取集合（表）
        MongoCollection<Document> collection = database.getCollection("mycollection");

// 创建文档（记录）
        Document document = new Document("name", "John Doe")
                .append("age", 30)
                .append("email", "johndoe@example.com");

// 插入文档
        collection.insertOne(document);
        System.out.println("插入成功！");

// 查询文档
        Document query = new Document("name", "John Doe");
        Document result = collection.find(query).first();
        System.out.println("查询结果：");
        System.out.println(result.toJson());

// 更新文档
        Document updateQuery = new Document("name", "John Doe");
        Document update = new Document("$set", new Document("age", 35));
        collection.updateOne(updateQuery, update);
        System.out.println("更新成功！");

// 删除文档
        Document deleteQuery = new Document("name", "John Doe");
        collection.deleteOne(deleteQuery);
        System.out.println("删除成功！");

// 关闭连接
        mongoClient.close();
    }
}
```

###5、打包Maven项目并运行
打包
>mvn package

进入target文件夹
>cd target

运行jar包
>nbu@ecs:~/bigdata/mongodb/mongodb_java/target$ java -jar mongodb_java-1.0-SNAPSHOT.jar

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