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在java中使用MongoDB数据库

Java

安装

要想在 Java 程序中使用 MongoDB，需要先确定是否安装了 MongoDB JDBC 驱动，并且要在机器上安装了 Java。查看 Java 教程来确保在机器上安装好 Java。下面来介绍如何安装 MongoDB JDBC 驱动。

从路径 Download mongo.jar 处下载 jar 文件，注意下载最新版本。
在类路径中包括 mongo.jar 文件。

连接数据库

为了连接数据库，需要指定数据库名称，如果数据库不存在，mongodb 就会自动创建它。

连接数据库的代码段如下所示：

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{   
         // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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() );
      }
   }
}

下面编译并运行上面的程序，以便测试数据库。可以针对每个需求改变路径。假设当前 JDBC 驱动版本 mongo-2.10.1.jar 可用于当前路径。

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

如果想使用 Windows 系统的机器，则编译并执行代码如下：

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

如果选定数据库的用户名及密码有效，则 auth 值为 true。

创建集合

创建集合需要使用 com.mongodb.DB 类的 createCollection() 方法。

创建集合的代码段如下所示：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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() );
      }
   }
}

编译并执行该程序，结果如下所示：

Connect to database successfully
Authentication: true
Collection created successfully

获取/选择一个集合

从数据库中获取/选择一个集合，使用 com.mongodb.DBCollection 类的 getCollection() 方法。代码段如下：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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() );
      }
   }
}

编译并执行该程序，结果如下所示：

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

插入文档

插入文档使用 com.mongodb.DBCollection 类的 insert() 方法。代码段如下所示：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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() );
      }
   }
}

编译并执行该程序，结果如下所示

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

检索所有文档

选择集合中的所有文档，使用 com.mongodb.DBCollection 类的 find() 方法。该方法返回一个游标，所以需要迭代该游标。

选择所有文档的代码如下所示：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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")
            col1.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() );
      }
   }
}

编译并执行程序的结果如下：

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Document updated successfully
Updated Document: 1
{
   "_id" : ObjectId(7df78ad8902c),
   "title": "MongoDB",
   "description": "database",
   "likes": 100,
   "url": "http://www.tutorialspoint.com/mongodb/",
   "by": "tutorials point"
}

更新文档

更新集合中的文档，使用 com.mongodb.DBCollection 类的 update() 方法。代码如下所示：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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")
            col1.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() );
      }
   }
}

程序编译及运行结果如下：

Connect to database successfully
Authentication: true
Collection mycol selected successfully
Document updated successfully
Updated Document: 1
{
   "_id" : ObjectId(7df78ad8902c),
   "title": "MongoDB",
   "description": "database",
   "likes": 100,
   "url": "http://www.tutorialspoint.com/mongodb/",
   "by": "tutorials point"
}

删除第一个文档

删除集合中的第一个文档，需要使用 findOne() 方法选中第一个文档，然后使用 com.mongodb.DBCollection 类的remove 方法将其删除。代码范例如下：

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{   
     // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );
         // Now connect to your databases
         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();
         col1.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() );
      }
   }
}

程序编译并执行结果如下所示：

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

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原文地址：https://www.cnblogs.com/wangshouchang/p/6187455.html