Mogodb connection test: mogodb connection

Mogodb connection test: mogodb connection

-$ In

db.Student.find({"_id":{"$in":[1001,1002,1]}})

-$ Or

db.Student.find({"$or":[{"_id":99},{"pageViews":2}]})

-And or

db.Student.find({"pageViews":2,"$or":[{"_id":99}]})

Cursor control

for(i=0;i<10;i++){    db.Student.insert({"_id":i});}var cursor=db.Student.find();cursor.forEach(function(x){    print(x);});

-Paging Query

db.Student.find().limit(3)     db.Student.find().limit(3).skip(3)

-Sort

Db. student. find (). sort ({"_ id":-1}) -- 1 is in ascending order, and-1 is in descending order. student. find (). sort ({"_ id":-1, "pageView": 1}) -- sort by the ascending order of pageView

DBHelper:

Package com. yc. link; import java.net. unknownHostException; import com. mongodb. DB; import com. mongodb. DBCollection; import com. mongodb. mongo; import com. mongodb. unknown exception; public class DBHelper {private static Mongo mongo = null; private DB db = null; static {try {mongo = new Mongo (Mypro. getInstance (). getProperty ("ip"), Integer. parseInt (Mypro. getInstance (). getProperty ("port");} catch (NumberFormatExcep Tion e) {e. printStackTrace ();} catch (UnknownHostException e) {e. printStackTrace ();} catch (except exception e) {// TODO Auto-generated catch block e. printStackTrace () ;}} public boolean getDB (String dbName, String name, String pwd) {mongo. getDB (dbName); if (name! = Null &&! "". Equals (name) & pwd! = Null &&! "". Equals (pwd) {if (db. authenticate (name, pwd. toCharArray () {return true;} else {return false;} else {// check whether the user name and password are specified in the configuration file String uname = Mypro. getInstance (). getProperty ("uname"); String pwds = Mypro. getInstance (). getProperty ("password"); if (name! = Null &&! "". Equals (name) & pwd! = Null &&! "". Equals (pwd) {if (db. authenticate (name, pwd. toCharArray () {return true;} else {return false ;}} return true;}/*** close link **/public void closeAll (Mongo mongo) {if (mongo! = Null) {mongo. close ();}} /*** get the database * User Name of the linked data * password of the Linked database */public DBCollection getDBCollection (String collectionName, string dbName) {DBCollection dbCollection = null; if (getDB (dbName, null, null) {db. requestStart (); if (collectionName = null) {// if it is null, load collectionName = Mypro in the configuration file. getInstance (). getProperty (collectionName);} dbCollection = db. getCollection (collectionName);} else {throw new RuntimeException ("database connection failed ..... ");} return dbCollection;} public DBCollection getDBCollection (String collectionName, String dbName, String name, String password) {DBCollection dbCollection = null; if (getDB (dbName, name, password) {db. requestStart (); if (collectionName = null) {// if it is null, load collectionName = Mypro in the configuration file. getInstance (). getProperty (collectionName);} dbCollection = db. getCollection (collectionName);} else {throw new RuntimeException ("database connection failed ..... ") ;}return dbCollection ;}}

Mypro: Singleton

package com.yc.link;import java.io.IOException;import java.io.InputStream;import java.util.Properties;public class Mypro extends Properties {        private static Mypro instance=new Mypro();        private Mypro(){            InputStream is=Mypro.class.getResourceAsStream("/db.properties");            try {                this.load(is);            } catch (IOException e) {                e.printStackTrace();            }finally{                if(is!=null){                    try {                        is.close();                    } catch (IOException e) {                        e.printStackTrace();                    }                }            }        }        public static Mypro getInstance(){            return instance;        }}

package com.yc.link;public class Test {    public static void main(String[] args) {            DBHelper db=new DBHelper();            System.out.println(db);    }}

Db. properties

ip=127.0.0.1port=27017dbName=uname=password=collectionName=

DBHelper should encapsulate more common methods. You can collect them online.

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