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：

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 { 
 
            /**** 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：

    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：