java mongodb 增删改查 工具类

package com.jttx.demo;

 

import com.mongodb.*;

import com.mongodb.util.JSON;

 

import java.net.UnknownHostException;

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.List;

 

 

/**

 * Created by superman on 2014/6/30.

 */

 

public class MongoManager {

    private DB db;

    private static final Integer soTimeOut = 300000;

    private static final Integer connectionsPerHost = 500;

    private static final Integer threadsAllowedToBlockForConnectionMultiplier = 500;

 

    public MongoManager(String host, int port, String database) {

        try {

            MongoClient mongoClient = new MongoClient(new ServerAddress(host, port), new MongoClientOptions.Builder()

                    .socketTimeout(soTimeOut)

                    .connectionsPerHost(connectionsPerHost)

                    .threadsAllowedToBlockForConnectionMultiplier(threadsAllowedToBlockForConnectionMultiplier)

                    .socketKeepAlive(true)

                    .build()

            );

            db = mongoClient.getDB(database);

        } catch (UnknownHostException e) {

            e.printStackTrace();

        }

    }

 

    public void save(String collection, DBObject dbObject) {

        db.getCollection(collection).save(dbObject);

    }

 

    public void delete(String collection, DBObject query) {

        db.getCollection(collection).remove(query);

    }

 

    // 此处不使用toArray()方法直接转换为List,是因为toArray()会把结果集直接存放在内存中，

    // 如果查询的结果集很大，并且在查询过程中某一条记录被修改了，就不能够反应到结果集中，从而造成"不可重复读"

    // 而游标是惰性获取数据

    public List<DBObject> find(String collection, DBObject query, DBObject fields, int limit) {

        List<DBObject> list = new LinkedList<>();

        Cursor cursor = db.getCollection(collection).find(query, fields).limit(limit);

        while (cursor.hasNext()) {

            list.add(cursor.next());

        }

        return list.size() > 0 ? list : null;

    }

 

    public List<DBObject> find(String collection, DBObject query, DBObject fields, DBObject orderBy, int pageNum, int pageSize) {

        List<DBObject> list = new ArrayList<>();

        Cursor cursor = db.getCollection(collection).find(query, fields).skip((pageNum - 1) * pageSize).limit(pageSize).sort(orderBy);

        while (cursor.hasNext()) {

            list.add(cursor.next());

        }

        return list.size() > 0 ? list : null;

    }

 

    public DBObject findOne(String collection, DBObject query, DBObject fields) {

        return db.getCollection(collection).findOne(query, fields);

    }

 

    public void update(String collection, DBObject query, DBObject update, boolean upsert, boolean multi) {

        db.getCollection(collection).update(query, update, upsert, multi);

    }

 

    public long count(String collection, DBObject query) {

        return db.getCollection(collection).count(query);

    }

 

 

    //查询出key字段,去除重复，返回值是{_id:value}形式的list

    public List distinct(String collection, String key, DBObject query) {

        return db.getCollection(collection).distinct(key, query);

    }

 

    //适用于小数据量查询

    public void distinctWithHandle(String collection, String key, DBObject query, CursorHandle cursorHandle) {

        List<DBObject> pipeLine = new ArrayList<>();

        pipeLine.add(new BasicDBObject("$match", query));

        String groupStr = String.format("{$group:{_id:'$%s'}}", key);

        pipeLine.add((DBObject) JSON.parse(groupStr));

        Cursor cursor = db.getCollection(collection).aggregate(pipeLine, AggregationOptions.builder().build());

        cursorHandle.handle(cursor);

    }

 

    //适用于大数据量查询

    public void distinctWithHandle(String collection, String key, DBObject query, int pageNo, int pageSize, CursorHandle cursorHandle) {

        List<DBObject> pipeLine = new ArrayList<>();

        pipeLine.add(new BasicDBObject("$match", query));

        String groupStr = String.format("{$group:{_id:'$%s'}}", key);

        pipeLine.add((DBObject) JSON.parse(groupStr));

        pipeLine.add(new BasicDBObject("$skip", (pageNo - 1) * pageSize));

        pipeLine.add(new BasicDBObject("$limit", pageSize));

        Cursor cursor = db.getCollection(collection).aggregate(pipeLine, AggregationOptions.builder().build());

        cursorHandle.handle(cursor);

    }

 

 

}

2. [代码]CursorHandle

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package com.jttx.demo;     import com.mongodb.Cursor;   /**  * Created by superman on 2014/9/15.  */ public interface CursorHandle {     public void handle(Cursor cursor); }

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