MongoDB系列教程（六）：java操作mongodb实例

MongoDB系列教程（六）：java操作mongodb实例

java操作mysql数据库的代码我们已经了如指掌了，增删改查，java对mongodb数据库也是类似的操作，先是数据库连接，再是进行操作。

首先我们进入进入admin数据库，然后建立自己的数据库testMongoDb，进入admin数据库后，就可以直接进入testMongoDb，因为用户可以进入系统的数据库，就是超级管理员，use testMongoDb后，为该数据库设置用户名和密码，db.addUser('root','root')，这样我们在程序中连该数据库，并实现增删改查，代码如下所示。

代码如下所示：

复制代码 代码如下:

package com.mkyong.core; 

import java.net.UnknownHostException; 

import java.util.Date; 

import com.mongodb.BasicDBObject; 

import com.mongodb.DB; 

import com.mongodb.DBCollection; 

import com.mongodb.DBCursor; 

import com.mongodb.Mongo; 

import com.mongodb.MongoException; 

/**

 * Java + MongoDB Hello world Example

 * 

 */ 

public class App { 

    public static void main(String[] args) { 

        try { 

       &nbspVEgOUbbeP;    /**** Connect to MongoDB ****/ 

            // Since 2.10.0, uses MongoClient 

            //MongoClient mongo = new MongoClient("localhost", 27017); 

            Mongo mongo = new Mongo("127.0.0.1",27017); 

            /**** Get database ****/ 

            // if database doesn't exists, MongoDB will create it for you 

            DB db = mongo.getDB("testMongoDb"); 

            //database username  root  and password root  

            boolean ok = db.authenticate("root","root".toCharArray()); 

            if(ok){ 

                System.out.println("db connection success！"); 

            }{ 

                System.out.println("db connection fail ！"); 

            } 

            /**** Get collection / table from 'testMongoDb' ****/ 

            // if collection doesn't exists, MongoDB will create it for you 

            DBCollection table = db.getCollection("user"); 

            /**** Insert ****/ 

            // create a document to store key and value 

            BasicDBObject document = new BasicDBObject(); 

            document.put("name", "mkyong"); 

            document.put("age", 30); 

            document.put("createdDate", new Date()); 

            table.insert(document); 

            /**** Find and display ****/ 

            BasicDBObject searchQuery = new BasicDBObject(); 

            searchQuery.put("name", "mkyong"); 

            DBCursor cursor = table.find(searchQuery); 

            while (cursor.hasNext()) { 

                System.out.println(cursor.next()); 

            } 

            /**** Update ****/ 

            // search document where name="mkyong" and update it with new values 

            BasicDBObject query = new BasicDBObject(); 

            query.put("name", "mkyong"); 

            BasicDBObject newDocument = new BasicDBObject(); 

            newDocument.put("name", "mkyong-updated"); 

            BasicDBObject updateObj = new BasicDBObject(); 

            updateObj.put("$set", newDocument); 

            table.update(query, updateObj); 

            /**** Find and display ****/ 

            BasicDBObject searchQuery2  

                = new BasicDBObject().append("name", "mkyong-updated"); 

            DBCursor cursor2 = table.find(searchQuery2); 

            while (cursor2.hasNext()) { 

                System.out.println(cursor2.next()); 

            } 

            /**** Done ****/ 

            System.out.println("Done"); 

        } catch (UnknownHostException e) { 

            e.printStackTrace(); 

        } catch (MongoException e) { 

            e.printStackTrace(); 

        } 

    } 

}

控制台输入结果如下：

复制代码 代码如下:

db connection success！

    db connection fail ！

{ "_id" : { "$oid" : "544073c4d58dfa6e469555ba"} , "name" : "mkyong" , "age" : 30 , "createdDate" : { "$date" : "2014-10-17T01:41:24.479Z"}}

{ "_id" : { "$oid" : "543e154bd58d704982fd38f0"} , "name" : "mkyong-updated" , "age" : 30 , "createdDate" : { "$date" : "2014-10-15T06:33:47.321Z"}}

{ "_id" : { "$oid" : "5440719dd58d08a207605c8e"} , "name" : "mkyong-updated" , "age" : 30 , "createdDate" : { "$date" : "2014-10-17T01:32:13.922Z"}}

{ "_id" : { "$oid" : "544073c4d58dfa6e469555ba"} , "name" : "mkyong-updated" , "age" : 30 , "createdDate" : { "$date" : "2014-10-17T01:41:24.479Z"}}

Done

源码下载：http://xiazai.jb51.net/201503/other/mongodb_helloworld.zip

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