MongoDB Java

环境配置

在Java程序中如果要使用MongoDB，你需要确保已经安装了Java环境及MongoDB JDBC 驱动。

你可以参考本站的Java教程来安装Java程序。现在让我们来检测你是否安装了 MongoDB JDBC 驱动。

首先你必须下载mongo jar包，下载地址：https://github.com/mongodb/mongo-java-driver/downloads, 请确保下载最新版本。

连接数据库

连接数据库，你需要指定数据库名称，如果指定的数据库不存在，mongo会自动创建数据库。

连接数据库的Java代码如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
		 // 连接到 mongodb 服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到数据库
         DB db = mongoClient.getDB( "test" 
		 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
		 System.out.println("Authentication: "+auth
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

现在，让我们来编译运行程序并创建数据库test。

你可以更加你的实际环境改变MongoDB JDBC驱动的路径。

本实例将MongoDB JDBC启动包 mongo-2.10.1.jar 放在本地目录下:

$javac MongoDBJDBC.java
$java -classpath ".:mongo-2.10.1.jar" MongoDBJDBC
Connect to database successfully
Authentication: true

如果你使用的是Window系统，你可以按以下命令来编译执行程序：

$javac MongoDBJDBC.java
$java -classpath ".;mongo-2.10.1.jar" MongoDBJDBC
Connect to database successfully
Authentication: true

如果用户名及密码正确，则Authentication 的值为true。

创建集合

我们可以使用com.mongodb.DB类中的createCollection()来创建集合

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
	     // 连接到 mongodb 服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth
         DBCollection coll = db.createCollection("mycol"
         System.out.println("Collection created successfully"
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection created successfully

获取集合

我们可以使用com.mongodb.DBCollection类的 getCollection() 方法来获取一个集合

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
	     // 连接到 mongodb 服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth
         DBCollection coll = db.createCollection("mycol"
         System.out.println("Collection created successfully"
         DBCollection coll = db.getCollection("mycol"
         System.out.println("Collection mycol selected successfully"
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection created successfully
Collection mycol selected successfully

插入文档

我们可以使用com.mongodb.DBCollection类的 insert() 方法来插入一个文档

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
		 // 连接到 mongodb 服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth         
         DBCollection coll = db.getCollection("mycol"
         System.out.println("Collection mycol selected successfully"
         BasicDBObject doc = new BasicDBObject("title", "MongoDB").
            append("description", "database").
            append("likes", 100).
            append("url", "//www.w3cschool.cn/mongodb/").
            append("by", "w3cschool.cn"
         coll.insert(doc
         System.out.println("Document inserted successfully"
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Document inserted successfully

检索所有文档

我们可以使用com.mongodb.DBCollection类中的 find() 方法来获取集合中的所有文档。

此方法返回一个游标，所以你需要遍历这个游标。

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
		// 连接到 mongodb 服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
          // 连接到数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth         
         DBCollection coll = db.getCollection("mycol"
         System.out.println("Collection mycol selected successfully"
         DBCursor cursor = coll.find(
         int i=1;
         while (cursor.hasNext()) { 
            System.out.println("Inserted Document: "+i 
            System.out.println(cursor.next() 
            i++;
         }
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Inserted Document: 1
{
   "_id" : ObjectId(7df78ad8902c),
   "title": "MongoDB",
   "description": "database",
   "likes": 100,
   "url": "//www.w3cschool.cn/mongodb/",
   "by": "w3cschool.cn"
}

更新文档

你可以使用 com.mongodb.DBCollection 类中的 update() 方法来更新集合中的文档。

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
	 // 连接到Mongodb服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到你的数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth         
         DBCollection coll = db.getCollection("mycol"
         System.out.println("Collection mycol selected successfully"
         DBCursor cursor = coll.find(
         while (cursor.hasNext()) { 
            DBObject updateDocument = cursor.next(
            updateDocument.put("likes","200")
            coll.update(updateDocument 
         }
         System.out.println("Document updated successfully"
         cursor = coll.find(
         int i=1;
         while (cursor.hasNext()) { 
            System.out.println("Updated Document: "+i 
            System.out.println(cursor.next() 
            i++;
         }
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Document updated successfully
Updated Document: 1
{
   "_id" : ObjectId(7df78ad8902c),
   "title": "MongoDB",
   "description": "database",
   "likes": 200,
   "url": "//www.w3cschool.cn/mongodb/",
   "by": "w3cschool.cn"
}

删除第一个文档

要删除集合中的第一个文档，首先你需要使用com.mongodb.DBCollection类中的 findOne()方法来获取第一个文档，然后使用remove 方法删除。

代码片段如下：

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBJDBC{
   public static void main( String args[] ){
      try{   
	 // 连接到Mongodb服务
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 
         // 连接到你的数据库
         DB db = mongoClient.getDB( "test" 
	 System.out.println("Connect to database successfully"
         boolean auth = db.authenticate(myUserName, myPassword
	 System.out.println("Authentication: "+auth         
         DBCollection coll = db.getCollection("mycol"
         System.out.println("Collection mycol selected successfully"
         DBObject myDoc = coll.findOne(
         coll.remove(myDoc
         DBCursor cursor = coll.find(
         int i=1;
         while (cursor.hasNext()) { 
            System.out.println("Inserted Document: "+i 
            System.out.println(cursor.next() 
            i++;
         }
         System.out.println("Document deleted successfully"
      }catch(Exception e){
	     System.err.println( e.getClass().getName() + ": " + e.getMessage() 
	  }
   }
}

编译运行以上程序，输出结果如下:

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Document deleted successfully

你还可以使用 save(), limit(), skip(), sort() 等方法来操作MongoDB数据库。