MongoDB系列之三：java操作MongoDB

第三章：Java连接MongoDB和简单的CRUD
第一步：准备工作：
首先下载驱动包：https://github.com/mongodb/mongo-java-driver/downloads
建立一个Java工程，导入下载下来的驱动包
第二步：Java连接MongoDB（在此之前需启动Mongo的服务和数据库）
简单的测试代码如下：
package com.yf.mongodb;

import java.net.UnknownHostException;

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

public class GetConnection {

public GetConnection() {
// TODO Auto-generated constructor stub
}

/**
* @param args
*/
public static void main(String[] args) {
Mongo mongo = null;
try {
//创建一个Mongo实例
mongo = new Mongo("localhost", 27017);
} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("The Database names are : "
+ mongo.getDatabaseNames());
System.out.println("The Database diver version is : "
+ mongo.getVersion());
//获取一个数据库
DB db = mongo.getDB("test");
System.out.println("The Test connections are : "
+ db.getCollectionNames());
//获取数据库连接
DBCollection conns = db.getCollection("student");
//获取数据库游标
DBCursor cur = conns.find();
while (cur.hasNext()) {
System.out.println(cur.next());
}
System.out.println(cur.count());
System.out.println(cur.getCursorId());
//数据库关闭和垃圾回收
if (cur != null)
cur.close();
cur = null;
conns = null;
db = null;
mongo = null;
System.gc();
}

}
第三步，进行简单的CRUD
首先，建立一个工具类，用于数据库连接，关闭等操作
package com.yf.mongodb;

import java.net.UnknownHostException;

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

public class MongoDBTools {
private static String URL = "localhost";
private static int port = 27017;
private static Mongo mongo = null;
private static DB db = null;
private static DBCollection conns = null;

//
public static DBCollection getConnection(String URL, int port,
String DBName, String connctionName) {

try {
mongo = new Mongo(URL, port);
db = mongo.getDB(DBName);
conns = db.getCollection(connctionName);
return conns;
} catch (UnknownHostException e) {
conns = null;
db = null;
mongo = null;
e.printStackTrace();
return null;
}
}

public static DBCollection getConnection(String DBName, String connctionName) {
return getConnection(URL, port, DBName, connctionName);
}
}
下面在编写一个CRUD的测试类，主要涉及一些简单的增删改查
package com.yf.mongodb;

import org.bson.types.ObjectId;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

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

public class CRUDTest {
private DBCollection dbConnection = null;
private final String DBName = "test";
private final String connectionName = "student";
private DBCursor cur = null;

@Before
public void init() {
dbConnection = MongoDBTools.getConnection(DBName, connectionName);
}

@After
public void destory() {
if (cur != null) {
cur.close();
}
cur = null;
dbConnection = null;
}
private void queryAndPrintAll(){
System.out.println("The query resulr is : ");
cur=this.dbConnection.find();
while(cur.hasNext()){
System.out.print(cur.next());
}
System.out.println("The query count is : "+cur.count());
}
@Test
public void add(){
queryAndPrintAll();
DBObject user = new BasicDBObject();
user.put("name", "yangfei");
user.put("age", 25);
user.put("sex", "男");
//保存数据
System.out.println(this.dbConnection.save(user).getN());
System.out.println(this.dbConnection.insert(new BasicDBObject("name","tome")).getN());
queryAndPrintAll();
}
@Test
public void remove(){
queryAndPrintAll();
System.out.println("删除id = 505eaa05c622fccace09cd2d：" + dbConnection.remove(new BasicDBObject("_id", new ObjectId("505eaa05c622fccace09cd2d"))).getN());
queryAndPrintAll();
}
@Test
public void modify(){
queryAndPrintAll();
System.out.println(dbConnection.update(new BasicDBObject("_id", new ObjectId("505eab57c622a6b21cb3d71c")), new BasicDBObject("age", 99)).getN());
queryAndPrintAll();
}
@Test
public void query(){
System.out.println("find id = 505ecab7c62264f0f3b2e03b: " + dbConnection.find(new BasicDBObject("_id", new ObjectId("505ecab7c62264f0f3b2e03b"))).toArray());
}
}
关于MongoDB的java API，可以在如下网站查看具体资料，
mongoDB对Java的相关支持、技术：http://www.mongodb.org/display/DOCS/Java+Language+Center
驱动源码下载：https://download.github.com/mongodb-mongo-java-driver-r2.6.1-7-g6037357.zip
在线查看源码：https://github.com/mongodb/mongo-java-driver