6. MongoDB——Java操作（增删改查）

import java.net.UnknownHostException;
import java.util.Iterator;
import java.util.Set; import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.Mongo;
import com.mongodb.MongoException; public class MongoMain { static DB db = null;
static DBCollection coll = null; static {
Mongo m = null;
try {
//m = new Mongo();//默认本地
//m = new Mongo("127.0.0.1");//默认端口
m = new Mongo("127.0.0.1",27017);
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MongoException e) {
e.printStackTrace();
} //获取名为 test 的数据库，不存在的情况下创建
db = m.getDB("test"); //登录数据库（用户名:test，密码:test）
boolean auth = db.authenticate("test", "test".toCharArray());
if(auth){
//只有admin中的用户才有此权限(show dbs)
//获取所有数据库，不显示无collection的db
//System.out.println("所有数据库名："+m.getDatabaseNames()); //获取名为 user 的collection(相当于表)，不存在的情况下创建
coll = db.getCollection("user");
}else{
System.out.println("登录失败!");
}
} public static void main(String[] args) {
MongoMain test = new MongoMain();
if(coll!=null){
test.saveData();
test.searchData();
test.updateData();
test.deleteData();
}
} /**
* 保存数据
*/
public void saveData(){
//录入学生1的信息
BasicDBObject stu1 = new BasicDBObject();
stu1.put("name", "jack");
stu1.put("age", "25");
BasicDBObject sight1 = new BasicDBObject();
sight1.put("left", 1.5);
sight1.put("right", 1.2);
stu1.put("sight", sight1); //录入学生2的信息
BasicDBObject stu2 = new BasicDBObject();
stu2.put("name", "lucy");
stu2.put("age", "22");
BasicDBObject sight2 = new BasicDBObject();
sight2.put("left", 1.0);
sight2.put("right", 1.3);
stu2.put("sight", sight2); //注意：不能直接对sight赋值{left:1.0,right:1.3} coll.insert(stu1);
coll.insert(stu2);
} /**
* 查询数据
*/
public void searchData(){
System.out.println("=======================");
//show collections
//获取数据库下所有的collection，不显示无数据的collection
Set<String> colls = db.getCollectionNames();
showData(colls); System.out.println("======================="); //查询coll中全部记录
DBCursor ite = coll.find();
showData(ite); System.out.println("======================="); //获取第一条记录
DBObject o = coll.findOne();
System.out.println(o); System.out.println("======================="); //统计colletion的数据条数
System.out.println(coll.getCount()); System.out.println("======================="); //查询 name为jack的对象
BasicDBObject query = new BasicDBObject();
query.put("name", "jack");
DBCursor it = coll.find(query);
showData(it); System.out.println("======================="); //查询age小于30，age不等于20的对象
BasicDBObject query2 = new BasicDBObject();
query2.put("age", new BasicDBObject("$lt", 30));
query2.put("age", new BasicDBObject("$ne", 20));
DBCursor it2 = coll.find(query2);
showData(it2);
} /**
* 修改数据
*/
public void updateData(){
BasicDBObject query = new BasicDBObject();
query.put("name", "lucy");
//这里的new_info对象一定要是find出的而不是new的，否则多字段的情况下就会丢失其它字段信息
DBObject new_info = coll.findOne(query); //方法一（缺点，必须把2个值都put进去）
BasicDBObject sight = new BasicDBObject();
sight.put("left", 1.3);
sight.put("right", 1.3);
new_info.put("sight", sight); //方法二（优点，只需设置要修改的字段的值）
DBObject obj = (DBObject)new_info.get("sight");
obj.put("right", 1.5); coll.update(query, new_info);
} /**
* 删除数据
*/
public void deleteData(){
BasicDBObject data = new BasicDBObject();
//删除名称为lucy的记录
data.put("name", "lucy");
//传入[空实例]删除所有
coll.remove(data);
} /**
* 遍历显示结果
* @param result
*/
@SuppressWarnings("rawtypes")
public void showData(Iterable result){
Iterator it = result.iterator();
while(it.hasNext())
{
System.out.println(it.next());
}
}
}