mongodb java id 查询数据_java 用 _id 查找 MongoDB 下的数据

找网上的资料看了下增删改查，等日后补上。

已经实现了数据的插入，现在想通过 _id属性来查找数据。一开始看到类似 55b321df715cc162076eb466 这么一长串的内容觉得是string类型。但是发现并不能搜索到结果，在网上搜到了解决方案：

String sid = "55b321df715cc162076eb466";

sitem.put("_id", new ObjectId(sid));

cursor = collection.find(sitem);

通过ObjectId类型就可以查找数据了。

demo源代码:

package persistence;

import java.net.UnknownHostException;

import java.util.Date;

import org.bson.types.ObjectId;

import net.sf.json.JSONObject;

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 domain.Article;

public class TestMongo {

public static void main(String[] args) {

Mongo mongo = null;

try {

// 8908 mongo.duapp.com smbWruErqVUXLgjDDSEG

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

System.out.println("connection success");

DB db = mongo.getDB("myblog");

DBCollection collection = db.getCollection("article");

BasicDBObject item = new BasicDBObject();

item.put("title", "Rectangle Area");

item.put("date", new Date());

item.put(

"extract",

"Find the total area covered by two rectilinear rectangles in a 2D plane. Each rectangle is defined by its bottom left corner and top right corner as shown in the figure.");

String content = "Assume that the total area is never beyond the maximum possible value of int.这道题求得是两个举行覆盖的面积。如果两个矩形没有相交的话直接返回两个矩形面积之和就可以了，如果有重合，那么再减去重合的面积即可。在如何计算重合面积上花费了一些时间，感觉思维还是有待加强。代码：";

item.put("content", content);

collection.insert(item);

String sid = "55b321df715cc162076eb466";

Object sido = new Object();

DBCursor cursor = collection.find();

while (cursor.hasNext()) {

// System.out.println("result:"+cursor.next());

DBObject o = cursor.next();

* String id =(String) o.get("_id").toString(); sido =

* o.get("_id"); System.out.println(id); sid = id; String title

* =(String) o.get("title"); System.out.println(title);

* Date date =(Date) o.get("date");