MongoDB学习（二）MongoDB Java增删查改

• 相关资料

1、MongoDB for Java的驱动包

　　https://github.com/mongodb/mongo-java-driver/downloads

2、在线文档

     http://www.mongodb.org/display/DOCS/Java+Language+Center

• 操作

1、查询某张表（在MongoDB中称之为集合）的所有数据

Java代码DBTest.java

package com.archie.mongodb;

import java.net.UnknownHostException;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoException;

/**
 * 查询指定数据库指定DBCollection集合中的所有数据
 * @author archie2010
 *
 * since 2012-9-29 下午10:40:21
 */
public class DBTest {
    public static void main(String[] args) throws UnknownHostException,
            MongoException {
        /**
           Mongo实例代表了一个数据库连接池
         * Mongo mg = new Mongo("localhost");
           Mongo mg = new Mongo("localhost", 27017);
         */
        Mongo mg = new Mongo();

        // 获取名为“dbtest”的数据库对象
        DB db = mg.getDB("dbtest");
        // 查询该库中所有的集合 (相当于表)
        for (String name : db.getCollectionNames()) {
            System.out.println("Collection Name: " + name);
        }
        DBCollection users = db.getCollection("emp");
        // 查询集合中所有的数据
        DBCursor cur = users.find();
        System.out.println("Record Count:" + cur.count());
        while (cur.hasNext()) {
            DBObject object = cur.next();
            System.out.println(object);
            // 取出对象中列表为字段名为'uname'和'upwd'的数据
            System.out.println("uname:" + object.get("uname") + "\tupwd:"
                    + object.get("upwd"));
        }
    }
}

运行结果：

2、对指定DBCollection集合的CRUD操作

Java代码

DBUtil.java

package com.archie.mongodb;

import java.net.UnknownHostException;

import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.Mongo;

/**
 * 获得DBCollection集合的工具类
 * @author archie2010
 *
 * since 2012-9-29 下午10:54:42
 */
public class DBUtil {

    public static Mongo mg=null;    
    public static DB db=null;    
    public static DBCollection collection;
    
    /**
     * 获得DBCollection对象
     * @param dbName
     * @param colName
     * @return
     */
    public static DBCollection getDBCollection(String dbName,String colName){
        if(mg==null){
            try {
                mg=new Mongo();
            } catch (UnknownHostException e) {
                e.printStackTrace();
            }
        }
        if(db==null){
            db=mg.getDB(dbName);
        }
        return db.getCollection(colName);
    }
}

CRUDTest.java

package com.archie.mongodb;

import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;

/**
 * 对指定DBCollection集合的CRUD操作
 * @author archie2010
 *
 * since 2012-9-29 下午10:51:24
 */
public class CRUDTest {
    /**
     * 增加
     * @param obj
     */
    public static void add(DBObject obj){
        DBCollection coll=DBUtil.getDBCollection("dbtest", "emp");
        coll.insert(obj);
    }
    /**
     * 删除
     * @param obj
     */
    public static void delete(DBObject obj){
        DBCollection coll=DBUtil.getDBCollection("dbtest", "emp");
        coll.remove(obj);
    }
    /**
     * 查询
     */
    public static void query(){
        DBCollection coll=DBUtil.getDBCollection("dbtest", "emp");
        // 查询集合中所有的数据
        DBCursor cur = coll.find();
        System.out.println("Record Count:" + cur.count());
        while (cur.hasNext()) {
            DBObject object = cur.next();
            System.out.println(object);
            // 取出对象中列表为'uname'和'upwd'的数据
            System.out.println("uname:" + object.get("uname") + "\tupwd:"
                    + object.get("upwd")+"\t_id:"+object.get("_id"));
        }
    }
    /**
     * 修改
     */
    public static void modify(DBObject orig,DBObject update){
        DBCollection coll=DBUtil.getDBCollection("dbtest", "emp");
        coll.update(orig, update, true, false);
    }
    public static void main(String[] args) {
        DBObject empObj=new BasicDBObject();
        empObj.put("uname", "teddy");
        empObj.put("upwd", "123456");
        //添加
        add(empObj);
        query();
        
        
        DBObject updateObj=new BasicDBObject();
        updateObj.put("uname", "teddy");
        updateObj.put("upwd", "3333");
        //更新
        modify(new BasicDBObject("uname","teddy"),updateObj);
        System.out.println("-----------------------修改后-------------------");
        query();
        
        //删除
        delete(new BasicDBObject("uname","teddy"));
        System.out.println("-----------------------删除后-------------------");
        query();
    }
}

运行效果：

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