鍍金池/ 教程/ 數(shù)據(jù)庫(kù)/ Java
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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(qū)動(dòng)，并且要在機(jī)器上安裝了 Java。查看 Java 教程來(lái)確保在機(jī)器上安裝好 Java。下面來(lái)介紹如何安裝 MongoDB JDBC 驅(qū)動(dòng)。

  • 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(shù)據(jù)庫(kù)

為了連接數(shù)據(jù)庫(kù)，需要指定數(shù)據(jù)庫(kù)名稱，如果數(shù)據(jù)庫(kù)不存在，mongodb 就會(huì)自動(dòng)創(chuàng)建它。

連接數(shù)據(jù)庫(kù)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() );
      }
   }
}

下面編譯并運(yùn)行上面的程序，以便測(cè)試數(shù)據(jù)庫(kù)?？梢葬槍?duì)每個(gè)需求改變路徑。假設(shè)當(dāng)前 JDBC 驅(qū)動(dòng)版本 mongo-2.10.1.jar 可用于當(dāng)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(tǒng)的機(jī)器，則編譯并執(zhí)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(shù)據(jù)庫(kù)的用戶名及密碼有效，則 auth 值為 true。

創(chuàng)建集合

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

創(chuàng)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() );
      }
   }
}

編譯并執(zhí)行該程序，結(jié)果如下所示： 

Connect to database successfully
Authentication: true
Collection created successfully

獲取/選擇一個(gè)集合

從數(shù)據(jù)庫(kù)中獲取/選擇一個(gè)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() );
      }
   }
}

編譯并執(zhí)行該程序，結(jié)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() );
      }
   }
}

編譯并執(zhí)行該程序，結(jié)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(gè)游標(biāo)，所以需要迭代該游標(biāo)。

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() );
      }
   }
}

編譯并執(zhí)行程序的結(jié)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(yùn)行結(jié)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(gè)文檔

刪除集合中的第一個(gè)文檔，需要使用 findOne() 方法選中第一個(gè)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() );
      }
   }
}

程序編譯并執(zhí)行結(jié)果如下所示： 

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

剩余的 mongodb 的 save()、limit()、skip()、sort() 等方法將在教程剩余部分予以介紹。