Java

安裝

要想在 Java 程序中使用 MongoDB，需要先確定是否安裝了 MongoDB JDBC 驅動，並且要在機器上安裝了 Java。查看 Java 教程來確保在機器上安裝好 Java。下面來介紹如何安裝 MongoDB JDBC 驅動。

從路徑 Download mongo.jar 處下載 jar 文件，注意下載最新版本。
在類路徑中包括 mongo.jar 文件。

連接數據庫

為了連接數據庫，需要指定數據庫名稱，如果數據庫不存在，mongodb 就會自動創建它。

連接數據庫的代碼段如下所示：

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() );
      }
   }
}

下面編譯並運行上面的程序，以便測試數據庫。可以針對每個需求改變路徑。假設當前 JDBC 驅動版本 mongo-2.10.1.jar 可用於當前路徑。

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

如果想使用 Windows 系統的機器，則編譯並執行代碼如下：

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

如果選定數據庫的用戶名及密碼有效，則 auth 值為 true。

創建集合

創建集合需要使用 com.mongodb.DB 類的 createCollection() 方法。

創建集合的代碼段如下所示：

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() );
      }
   }
}

編譯並執行該程序，結果如下所示：

Connect to database successfully
Authentication: true
Collection created successfully

獲取/選擇一個集合

從數據庫中獲取/選擇一個集合，使用 com.mongodb.DBCollection 類的 getCollection() 方法。代碼段如下：

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() );
      }
   }
}

編譯並執行該程序，結果如下所示：

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

插入文檔

插入文檔使用 com.mongodb.DBCollection 類的 insert() 方法。代碼段如下所示：

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() );
      }
   }
}

編譯並執行該程序，結果如下所示

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

檢索所有文檔

選擇集合中的所有文檔，使用 com.mongodb.DBCollection 類的 find() 方法。該方法返回一個游標，所以需要迭代該游標。

選擇所有文檔的代碼如下所示：

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() );
      }
   }
}

編譯並執行程序的結果如下：

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"
}

更新文檔

更新集合中的文檔，使用 com.mongodb.DBCollection 類的 update() 方法。代碼如下所示：

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() );
      }
   }
}

程序編譯及運行結果如下：

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"
}

刪除第一個文檔

刪除集合中的第一個文檔，需要使用 findOne() 方法選中第一個文檔，然后使用 com.mongodb.DBCollection 類的remove 方法將其刪除。代碼范例如下：

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() );
      }
   }
}

程序編譯並執行結果如下所示：

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

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