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。

转自：http://www.cnblogs.com/qiyadeng/archive/2013/03/19/2970131.html