package com.infomorrow.webroot;
import java.util.List;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.DBObject;
import com.mongodb.MongoClient;
public class test_mongodb {
public static void main(String args[]) throws Exception {
MongoClient mongoClient = new MongoClient( "127.0.0.1" , 27017 );//建立连接
DB get_db_credit = mongoClient.getDB("credit_2");//数据库名
DBCollection collection = get_db_credit.getCollection("report");//集合名,对应mysql中的表名
BasicDBObject filter_dbobject = new BasicDBObject();
//建立查询条件,如果还有其他条件,类似的写即可
// 如:version=3,filter_dbobject.put("version", 3),mongod区分String 和 Integer类型,所以要小心"3"!=3
filter_dbobject.put("user_id", "10065716153075");
//下面执行查询,设置limit,只要10条数据,排序(类mysql orderby) 再建一个BasicDBObject即可,-1表示倒序
DBCursor cursor = collection.find(filter_dbobject).limit(10).sort(new BasicDBObject("create_time",-1));
//把结果集输出成list类型
List<DBObject> list = cursor.toArray();
System.out.println(list.size());//list的长度
System.err.println(cursor.count());//计算结果的数量,类似于(mysql count()函数),不受limit的影响
//遍历结果集
while(cursor.hasNext()) {
System.out.println(cursor.next());
}
}
}
关于查询:如果想要查 “a=30或a=50”这样的条件怎么办?
可以使用$in进行查询:
public void testIn(){
//a=30或者a=50
DBObject queryCondition = new BasicDBObject();
BasicDBList values = new BasicDBList();
values.add(30);
values.add(50);
queryCondition.put("a", new BasicDBObject("$in", values));
DBCursor dbCursor = coll.find(queryCondition);
}
2.关于查询:如果想要查 “a>30或a<10”这样的条件怎么办?
可以使用$or进行查询:
public void testOrSingleField(){
DBObject queryCondition = new BasicDBObject();
//查询a<10 OR a>30
BasicDBList values = new BasicDBList();
values.add(new BasicDBObject("a", new BasicDBObject("$gt", 30)));
values.add(new BasicDBObject("a", new BasicDBObject("$lt", 10)));
queryCondition.put("$or", values);
DBCursor dbCursor = coll.find(queryCondition);
}
那么,如果想要查 “a>30或b<10”这样的条件怎么办?
只需要将上面代码改为如下,即可:
values.add(new BasicDBObject("b", new BasicDBObject("$lt", 10)));
3.如果是多值and查询只用new BasicDBobject(),然后再put即可,如下所示:
BasicDBObject basic=new BasicDBObject();
basic.put("name","amosli");
basic.put("hobby","code");
....
collection.find(basic).toArray();//将值转为list
4查询非操作
查询level为INFO,但status不为"已完成"的所结果数
//not equal 非操作
BasicDBObject basicDBObject = new BasicDBObject("level","INFO");
System.out.println(collection.count(basicDBObject.append("status", new BasicDBObject("$ne", "已完成"))));
5.使用skip跳过少量的数据是很好的选择,但是如果跳过大量的数据的时候,skip方法就会执行的很慢。所以我们要尽量的避免使用skip跳过大量的数据
public List<User> pageList(int page,int pageSize){
DB myMongo = MongoManager.getDB("myMongo");
DBCollection userCollection = myMongo.getCollection("user");
DBCursor limit = userCollection.find().skip((page - 1) * 10).sort(new BasicDBObject()).limit(pageSize); List<User> userList = new ArrayList<User>();
while (limit.hasNext()) {
User user = new User();
user.parse(limit.next());
userList.add(user);
}
return userList;
}