import java.net.UnknownHostException;import com.mongodb.BasicDBList;import com.mongodb.BasicDBObject;import com.mongodb.DB;import com.mongodb.DBCollection;import com.mongodb.Mongo;public class MongoDBTest {	private static DB db = null; 		static{		Mongo mongo = null;		try {			mongo = new Mongo("localhost", 27017);		} catch (UnknownHostException e) {			e.printStackTrace();		}		db = mongo.getDB("TestDB");	//连接数据	}		/**	 * select count(*) from list	 */	public Long m1() {		DBCollection collection = db.getCollection("list");		return collection.count();	}		/**	 * select count(*) from list where userId = 'orange'	 */	public Long m2(){		DBCollection listCollection = db.getCollection("list");		BasicDBObject query =new BasicDBObject();		query.put("userId", "orange");		return listCollection.count(query);	}			/**	 * select count(*) from list where userId = 'orange' and time >= '20101201' and time <= '20101211'	 */	public Long m3(){		DBCollection listCollection = db.getCollection("list");		BasicDBObject query =new BasicDBObject();		query.put("userId","orange");		query.put("time", new BasicDBObject("$gte", "20101201").append("$lte", "20101211"));		return listCollection.count(query);	}	/**	 * select count(distinct(userId)) from detail where time >= '20101201' and time <='20101211'	 */	public int m4() {  		DBCollection collection = db.getCollection("detail");		BasicDBObject query = new BasicDBObject(); 		query.put("time", new BasicDBObject("$gte", "20101201").append("$lte", "20101211")); 		return collection.distinct("userId", query).size();	}			/**	 * select date_format(time, '%Y-%m-%d %H') as sj ,count(*) from detail group by sj	 */	public void m5() {		DBCollection collection = db.getCollection("detail");		String formatDate = "function(obj,doc){"				+ "var date = new Date(doc.time);"				+ "var dateKey = date.getFullYear()+\"-\"+(date.getMonth()+1)+\"-\"+date.getDate(); "				+ "return {'time':datekey}" + "}";		BasicDBObject key = new BasicDBObject();		key.put(formatDate, true); // 要分组的列		BasicDBObject query = new BasicDBObject(); // where条件		String reduce = "function (obj, prev) {prev.count++}";		BasicDBObject initial = new BasicDBObject();		initial.append("count", 0); // 每列初始值		BasicDBList group = (BasicDBList) collection.group(key, query, initial,	reduce);		System.out.println(group);	}}