找網(wǎng)上的資料看了下增刪改查，等日后補上。

已經(jīng)實現(xiàn)了數(shù)據(jù)的插入，現(xiàn)在想通過 _id屬性來查找數(shù)據(jù)。一開始看到 類似?55b321df715cc162076eb466 這么一長串的內(nèi)容覺得是string類型。但是發(fā)現(xiàn)并不能搜索到結(jié)果，在網(wǎng)上搜到了解決方案：

String sid = "55b321df715cc162076eb466";

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

cursor = collection.find(sitem);

通過ObjectId類型就可以查找數(shù)據(jù)了。

demo源代碼:

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.這道題求得是兩個舉行覆蓋的面積。如果兩個矩形沒有相交的話直接返回兩個矩形面積之和就可以了，如果有重合，那么再減去重合的面積即可。在如何計算重合面積上花費了一些時間，感覺思維還是有待加強。代碼：";

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");

* System.out.println(date.getDate());

*

* String extract =(String) o.get("extract");

* System.out.println(extract);

*/

System.out.println("search for id:" + sid);

BasicDBObject sitem = new BasicDBObject();

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

cursor = collection.find(sitem);

while (cursor.hasNext()) {

System.out.println("found result:");

System.out.println(cursor.next().get("date").toString());

}

}

} catch (Exception e) {

e.printStackTrace();

}

}

}

結(jié)果：

總結(jié)

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