MongoDB Java

Environment configuration

If you want to use MongoDB in a Java program, you need to ensure that the Java environment and MongoDB JDBC driver have been installed.

The examples in this chapter are based on Mongo 3.x or above.

You can refer to the Java tutorial on this site to install the Java program. Now let's check if you have the MongoDB JDBC driver installed.

First you must download the mongo jar package, download address: http://mongodb.github.io/mongo-java-driver/, Please make sure to download the latest version.
You need to mongo-java-driver-3.2.2.jar (find the appropriate version) included in your classpath. .
Domestic mongodb-driver jar download address: http://central.maven.org/maven2/org/mongodb/mongo-java-driver/

Connect to the database

To connect to the database, you need to specify the database name. If the specified database does not exist, mongo will automatically create the database.

The Java code to connect to the database is as follows:

import com.mongodb.MongoClient;
import com.mongodb.client.MongoDatabase;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
       System.out.println("Connect to database successfully");
        
      }catch(Exception e){
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
     }
   }
}

Now, let us compile and run the program and connect to the database test.

You can change the path of the MongoDB JDBC driver according to your actual environment.

In this example, the MongoDB JDBC startup package mongo-java-driver-3.2.2.jar is placed in the local directory:

$ javac -cp .:mongo-java-driver-3.2.2.jar MongoDBJDBC.java
$ java -cp .:mongo-java-driver-3.2.2.jar MongoDBJDBC
Connect to database successfully
Authentication: true

In this example, the Mongo database does not require username and password authentication. If your Mongo needs to verify the user name and password, you can use the following code:

import java.util.ArrayList;  
import java.util.List;  
import com.mongodb.MongoClient;  
import com.mongodb.MongoCredential;  
import com.mongodb.ServerAddress;  
import com.mongodb.client.MongoDatabase;  
  
public class MongoDBJDBC {  
    public static void main(String[] args){  
        try {  
            //连接到MongoDB服务 如果是远程连接可以替换“localhost”为服务器所在IP地址  
            //ServerAddress()两个参数分别为 服务器地址 和 端口  
            ServerAddress serverAddress = new ServerAddress("localhost",27017);  
            List<ServerAddress> addrs = new ArrayList<ServerAddress>();  
            addrs.add(serverAddress);  
              
            //MongoCredential.createScramSha1Credential()三个参数分别为 用户名 数据库名称 密码  
            MongoCredential credential = MongoCredential.createScramSha1Credential("username", "databaseName", "password".toCharArray());  
            List<MongoCredential> credentials = new ArrayList<MongoCredential>();  
            credentials.add(credential);  
              
            //通过连接认证获取MongoDB连接  
            MongoClient mongoClient = new MongoClient(addrs,credentials);  
              
            //连接到数据库  
            MongoDatabase mongoDatabase = mongoClient.getDatabase("databaseName");  
            System.out.println("Connect to database successfully");  
        } catch (Exception e) {  
            System.err.println( e.getClass().getName() + ": " + e.getMessage() );  
        }  
    }  
}

Create a collection

We can use createCollection() in the com.mongodb.client.MongoDatabase class To create a collection

The code snippet is as follows:

import com.mongodb.MongoClient;
import com.mongodb.client.MongoDatabase;

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
      MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
      System.out.println("Connect to database successfully");
      mongoDatabase.createCollection("test");
      System.out.println("集合创建成功");
        
      }catch(Exception e){
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
     }
   }
}

Compile and run the above program, the output result is as follows:

Connect to database successfully
集合创建成功

Get the collection

We can use Use the getCollection() method of the com.mongodb.client.MongoDatabase class to obtain a collection

The code snippet is as follows:

import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
       System.out.println("Connect to database successfully");
      
       MongoCollection<Document> collection = mongoDatabase.getCollection("test");
       System.out.println("集合 test 选择成功");
      }catch(Exception e){
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
     }
   }
}

Compile and run the above program, the output result is as follows:

Connect to database successfully
集合 test 选择成功

Insert document

We can use the insertMany() method of the com.mongodb.client.MongoCollection class to insert a document

The code snippet is as follows:

import java.util.ArrayList;
import java.util.List;
import org.bson.Document;

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
         System.out.println("Connect to database successfully");
         
         MongoCollection<Document> collection = mongoDatabase.getCollection("test");
         System.out.println("集合 test 选择成功");
         //插入文档  
         /** 
         * 1. 创建文档 org.bson.Document 参数为key-value的格式 
         * 2. 创建文档集合List<Document> 
         * 3. 将文档集合插入数据库集合中 mongoCollection.insertMany(List<Document>) 插入单个文档可以用 mongoCollection.insertOne(Document) 
         * */
         Document document = new Document("title", "MongoDB").  
         append("description", "database").  
         append("likes", 100).  
         append("by", "Fly");  
         List<Document> documents = new ArrayList<Document>();  
         documents.add(document);  
         collection.insertMany(documents);  
         System.out.println("文档插入成功");  
      }catch(Exception e){
         System.err.println( e.getClass().getName() + ": " + e.getMessage() );
      }
   }
}

Compile and run The output of the above program is as follows:

Connect to database successfully
集合 test 选择成功
文档插入成功

Retrieve all documents

We can use the find() method in the com.mongodb.client.MongoCollection class to obtain all documents in the collection .

This method returns a cursor, so you need to traverse this cursor.

The code snippet is as follows:

import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
         System.out.println("Connect to database successfully");
         
         MongoCollection<Document> collection = mongoDatabase.getCollection("test");
         System.out.println("集合 test 选择成功");
         
         //检索所有文档  
         /** 
         * 1. 获取迭代器FindIterable<Document> 
         * 2. 获取游标MongoCursor<Document> 
         * 3. 通过游标遍历检索出的文档集合 
         * */  
         FindIterable<Document> findIterable = collection.find();  
         MongoCursor<Document> mongoCursor = findIterable.iterator();  
         while(mongoCursor.hasNext()){  
            System.out.println(mongoCursor.next());  
         }  
      
      }catch(Exception e){
         System.err.println( e.getClass().getName() + ": " + e.getMessage() );
      }
   }
}

Compile and run the above program, the output result is as follows:

Connect to database successfully
集合 test 选择成功
Document{{_id=56e65fb1fd57a86304fe2692, title=MongoDB, description=database, likes=100, by=Fly}}

Update document

You can use com.mongodb The updateMany() method in the .client.MongoCollection class to update documents in the collection.

The code snippet is as follows:

import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
         System.out.println("Connect to database successfully");
         
         MongoCollection<Document> collection = mongoDatabase.getCollection("test");
         System.out.println("集合 test 选择成功");
         
         //更新文档   将文档中likes=100的文档修改为likes=200   
         collection.updateMany(Filters.eq("likes", 100), new Document("$set",new Document("likes",200)));  
         //检索查看结果  
         FindIterable<Document> findIterable = collection.find();  
         MongoCursor<Document> mongoCursor = findIterable.iterator();  
         while(mongoCursor.hasNext()){  
            System.out.println(mongoCursor.next());  
         }  
      
      }catch(Exception e){
         System.err.println( e.getClass().getName() + ": " + e.getMessage() );
      }
   }
}

Compile and run the above program, the output result is as follows:

Connect to database successfully
集合 test 选择成功
Document{{_id=56e65fb1fd57a86304fe2692, title=MongoDB, description=database, likes=200, by=Fly}}

Delete the first document

To delete the first document in the collection, first you need to use the com.mongodb.DBCollection class findOne() method to get the first document, and then use the remove method to delete it.

The code snippet is as follows:

import org.bson.Document;
import com.mongodb.MongoClient;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;

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
         MongoDatabase mongoDatabase = mongoClient.getDatabase("mycol");  
         System.out.println("Connect to database successfully");

         MongoCollection<Document> collection = mongoDatabase.getCollection("test");
         System.out.println("集合 test 选择成功");

         //删除符合条件的第一个文档  
         collection.deleteOne(Filters.eq("likes", 200));  
         //删除所有符合条件的文档  
         collection.deleteMany (Filters.eq("likes", 200));  
         //检索查看结果  
         FindIterable<Document> findIterable = collection.find();  
         MongoCursor<Document> mongoCursor = findIterable.iterator();  
         while(mongoCursor.hasNext()){  
           System.out.println(mongoCursor.next());  
         }  
           
      }catch(Exception e){
        System.err.println( e.getClass().getName() + ": " + e.getMessage() );
     }
   }
}

Compile and run the above program, the output result is as follows:

Connect to database successfully
集合 test 选择成功

For more operations, please refer to: http://mongodb.github. io/mongo-java-driver/3.0/driver/getting-started/quick-tour/

Reference documentation: http://blog.csdn.net/ererfei/article/details/50857103

MongoDB Java

Connect to the database

Create a collection

Get the collection

Insert document

Retrieve all documents

Update document

Delete the first document

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