MongoDB与JAVA CRUD

本文介绍java如何对MongoDB数据库进行CRUD操作。

1、测试环境

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（1） OS：windows XP

（2） DataBase：MongoDB V 1.8.1

（3） Driver：mongo-2.6.5.jar

（4） Test：junit-4.10.jar

2、初始化连接

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private Mongo mongo = null;

private DB db = null;

private DBCollection dbCollection = null;

@Before

public void init(){

try {

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

db = mongo.getDB("test");

dbCollection = db.getCollection("emp");

} catch (UnknownHostException e) {

e.printStackTrace();

} catch (MongoException e) {

e.printStackTrace();

}

}

上述代码是连接MongoDB数据库的，基本上分为三步：

（1）建立连接 （2）获取要操作的数据库实例 （3）获取要操作的集合实例

3、关闭连接

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@After

public void destroy(){

if(mongo != null){

mongo.close();

mongo = null;

db = null;

dbCollection = null;

}

4、CRUD操作

（1）C---插入记录

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/**

* 插入10条记录

* 指定_id

*/

@Test

public void testCreate(){

DBObject obj = null;

for(int i=1;i<=10;i++){

obj = new BasicDBObject("_id",i).append("name", "yy"+i).append("age", i*10);

dbCollection.save(obj);

}

}

插入新的记录时，上述代码使用的是save接口。

（2）R—查询所有记录

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@Test

public void testReadAll(){

DBCursor cursor = dbCollection.find();

while(cursor.hasNext()){

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

}

}

结果如下：

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{ "_id" : 1 , "name" : "yy1" , "age" : 10}

{ "_id" : 2 , "name" : "yy2" , "age" : 20}

{ "_id" : 3 , "name" : "yy3" , "age" : 30}

{ "_id" : 4 , "name" : "yy4" , "age" : 40}

{ "_id" : 5 , "name" : "yy5" , "age" : 50}

{ "_id" : 6 , "name" : "yy6" , "age" : 60}

{ "_id" : 7 , "name" : "yy7" , "age" : 70}

{ "_id" : 8 , "name" : "yy8" , "age" : 80}

{ "_id" : 9 , "name" : "yy9" , "age" : 90}

{ "_id" : 10 , "name" : "yy10" , "age" : 100}

（3） R—根据主键ID查询记录

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@Test

public void testReadOneWithId(){

DBObject obj = dbCollection.findOne(new BasicDBObject("_id",1));

System.out.println(obj);

}

结果如下：

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{ "_id" : 1 , "name" : "yy1" , "age" : 10}

（4）R—模糊查询

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@Test

public void testReadPuzzy(){

Pattern pattern = Pattern.compile("^yy1");

BasicDBObject obj = new BasicDBObject("name",pattern);

DBCursor cursor = dbCollection.find(obj);

while(cursor.hasNext()){

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

}

}

模糊查询使用到了正则表达式。

结果如下：

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{ "_id" : 1 , "name" : "yy1" , "age" : 10}

{ "_id" : 10 , "name" : "yy10" , "age" : 100}

（5） U—修改记录

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@Test

public void testUpdate(){

BasicDBObject condition = new BasicDBObject("_id",10);

BasicDBObject res = new BasicDBObject("name","yy10_new");

BasicDBObject res2 = new BasicDBObject("$set",res); //若没有此语句，直接调用下面的语句，返回结果{ "_id" : 10 , "name" : "yy10_new"}

dbCollection.update(condition, res2);

System.out.println(dbCollection.findOne(new BasicDBObject("_id",10)));

}

结果如下：

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{ "_id" : 10 , "age" : 100 , "name" : "yy10_new"}

（6） D—删除记录

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@Test

public void testDelete(){

dbCollection.remove(new BasicDBObject("_id",10));

testReadAll();

}

结果如下：

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{ "_id" : 1 , "name" : "yy1" , "age" : 10}

{ "_id" : 2 , "name" : "yy2" , "age" : 20}

{ "_id" : 3 , "name" : "yy3" , "age" : 30}

{ "_id" : 4 , "name" : "yy4" , "age" : 40}

{ "_id" : 5 , "name" : "yy5" , "age" : 50}

{ "_id" : 6 , "name" : "yy6" , "age" : 60}

{ "_id" : 7 , "name" : "yy7" , "age" : 70}

{ "_id" : 8 , "name" : "yy8" , "age" : 80}

{ "_id" : 9 , "name" : "yy9" , "age" : 90}

上述简单介绍了JAVA实现MongoDB数据库 CRUD的操作步骤。