Java和MongoDB之Hello World

1.新建Project

新建Java Project，并把mongo-java-driver驱动加入到项目bulid path中，如果你使用的是maven增加依赖。

       < dependency >
           < groupId > org.mongodb </ groupId >
           < artifactId > mongo-java-driver </ artifactId >
           < version > 2.10.1 </ version >
       </ dependency >

2.连接上MongoDB

// >2.10版本
MongoClient mongo  =   new  MongoClient(  " localhost "  ,  27017  );

// 老版本  
Mongo mongo  =   new  Mongo( " localhost " ,  27017 );

如果需要验证，需要输入用户名和密码

    MongoClient mongoClient  =   new  MongoClient();
    DB db  =  mongoClient.getDB( " database name " );
     boolean  auth  =  db.authenticate( " username " ,  " password " .toCharArray());

3.MongoDB数据库

得到MongoDB中的数据库，如果数据库名不存在，MongoDB会自动创建

DB db  =  mongo.getDB( " database name " );

显示所有的数据库

    List < String >  dbs  =  mongo.getDatabaseNames();
     for (String db : dbs){
        System.out.println(db);
    }

4.MongoDB Collection（MongoDB表）

得到数据库中的表

    DB db  =  mongo.getDB( " testdb " );
    DBCollection table  =  db.getCollection( " user " );

显示数据库中的所有表

    DB db  =  mongo.getDB( " testdb " );
    Set < String >  tables  =  db.getCollectionNames();
 
     for (String coll : tables){
        System.out.println(coll);
    }

5.插入、查找、更新、删除操作

插入数据，向Collection（表）中插入一个Document

    DBCollection table  =  db.getCollection( " user " );
    BasicDBObject document  =   new  BasicDBObject();
    document.put( " name " ,  " qiyadeng " );
    document.put( " age " ,  30 );
    document.put( " createdDate " ,  new  Date());
    table.insert(document);

更新Document中的name="qiyadeng.com"

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

     BasicDBObject query  =   new  BasicDBObject();
    query.put( " name " ,  " qiyadeng " );

    BasicDBObject newDocument  =   new  BasicDBObject();
    newDocument.put( " name " ,  " qiyadeng.com " );

    BasicDBObject updateObj  =   new  BasicDBObject();
    updateObj.put( " $set " , newDocument);
 
    table.update(query, updateObj);

从Collection中查找name="qiyadeng.com"的Document

    DBCollection table  =  db.getCollection( " user " );
 
    BasicDBObject searchQuery  =   new  BasicDBObject();
    searchQuery.put( " name " ,  " qiyadeng.com " );
 
    DBCursor cursor  =  table.find(searchQuery);
 
     while  (cursor.hasNext()) {
        System.out.println(cursor.next());
    }

删除name="qiyadeng"的Document

    DBCollection table  =  db.getCollection( " user " );
 
    BasicDBObject searchQuery  =   new  BasicDBObject();
    searchQuery.put( " name " ,  " qiyadeng.com " );
 
    table.remove(searchQuery);

6.完整的例子

package  com.qiyadeng.mongodb;


import  java.util.Date;

import  com.mongodb.BasicDBObject;
import  com.mongodb.DB;
import  com.mongodb.DBCollection;
import  com.mongodb.DBCursor;
import  com.mongodb.MongoClient;

public   class  MongoDBSample {

     public   static   void  main(String[] args)  throws  Exception{
             
             /** ** Connect to MongoDB *** */
             // 2.10.0后,使用MongoClient
            MongoClient mongo  =   new  MongoClient( " localhost " ,  27017 );
         
             /** ** Get database *** */
             //  if database doesn't exists, MongoDB will create it for you
            DB db  =  mongo.getDB( " testdb " );
         
             /** ** Get collection / table from 'testdb' *** */
             //  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 " ,  " qiyadeng " );
            document.put( " age " ,  30 );
            document.put( " createdDate " ,  new  Date());
            table.insert(document);
         
             /** ** Find and display *** */
            BasicDBObject searchQuery  =   new  BasicDBObject();
            searchQuery.put( " name " ,  " qiyadeng " );
         
            DBCursor cursor  =  table.find(searchQuery);
         
             while  (cursor.hasNext()) {
                System.out.println(cursor.next());
            }
         
             /** ** Update *** */
             //  search document where name="qiyadeng" and update it with new values
            BasicDBObject query  =   new  BasicDBObject();
            query.put( " name " ,  " qiyadeng " );
         
            BasicDBObject newDocument  =   new  BasicDBObject();
            newDocument.put( " name " ,  " qiyadeng.com " );
         
            BasicDBObject updateObj  =   new  BasicDBObject();
            updateObj.put( " $set " , newDocument);
         
            table.update(query, updateObj);
         
             /** ** Find and display *** */
            BasicDBObject searchQuery2 
                 =   new  BasicDBObject().append( " name " ,  " qiyadeng.com " );
         
            DBCursor cursor2  =  table.find(searchQuery2);
         
             while  (cursor2.hasNext()) {
                System.out.println(cursor2.next());
            }
    }
}

输出

{  " _id "  : {  " $oid "  :  " 51444c88874c79654063356b " } ,  " name "  :  " qiyadeng "  ,  " age "  :  30  ,  " createdDate "  : {  " $date "  :  " 2013-03-16T10:42:16.555Z " }}
{  " _id "  : {  " $oid "  :  " 51444c88874c79654063356b " } ,  " age "  :  30  ,  " createdDate "  : {  " $date "  :  " 2013-03-16T10:42:16.555Z " } ,  " name "  :  " qiyadeng.com " }

使用mongo验证创建的数据库testdb，collection user是否存在。

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