Connect to MongoDB using Java, operate on mongodb, and connect to MongoDB using java

Connect to MongoDB using Java, operate on mongodb, and connect to MongoDB using java

Java is very simple to connect to MongoDB. Specifically, there are two steps:
1: import the java-mongo driver package to the new project.
:

2: create a link help class to complete the link operation

Package com. yc. mongodb; import java. util. iterator; import java. util. set; 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 com. mongodb. writeResult; public class extends link2 {public static void main (String [] args) {Mongo mongo = null; DB db = null; try {// link to the mongo server mongo = new Mongo ("127.0.0.1", 27017); // obtain the database object based on the mongodb Database Name and connect to the database yc DB = mongo. getDB ("yc"); // send the request to obtain the db. requestStart (); // obtain the Set <String> collections = db. getCollectionNames (); Iterator itr = collections. iterator (); // iterative output while (itr. hasNext () {System. out. println (itr. next ();} DBCollection dbObject = db. getCollection ("yc"); DBObject object = null; // Add object = new BasicDBObject (); object. put ("_ id", 1003); object. put ("n Ame "," Zhang San "); object. put ("sex", "male"); WriteResult rs = dbObject. insert (object); object. put ("_ id", 1002); // remove dbObject. remove (new BasicDBObject (); // query all DBCursor cursor = dbObject. find (); while (cursor. hasNext () {object = cursor. next (); System. out. println (object) ;}} catch (Exception e) {e. printStackTrace ();} finally {if (mongo! = Null) {mongo. close ();}}}}

The running result is as follows:

At this point, it is actually ready for use. The code coupling is too high, the function binding is too serious, and it is not convenient to call,
Then encapsulate it.

First define an attribute file:

It defines some basic configurations, such as the user name, database name, ip address, and port.
Next, define a class to read the file. It is better to define the file as a singleton,

package com.yc.mongodb;import java.io.IOException;import java.io.InputStream;import java.util.Properties;@SuppressWarnings("serial")public class MyPro extends Properties{    private static MyPro instanece=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 instanece;    }}

Define a DBHelper class like oracle to encapsulate data operations:
As follows:

Package com. yc. mongodb; 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; private DBCollection collection = null; static {try {mongo = new Mongo (MyPro. getInstance (). getProperty ("ip"), Integer. parseInt (MyPro. getInstance (). getPrope Rty ("port");} catch (NumberFormatException e) {e. printStackTrace ();} catch (UnknownHostException e) {e. printStackTrace ();} catch (except exception e) {e. printStackTrace ();} System. out. println (mongo);}/***** @ param dbName * @ param name * @ param pwd * @ return */public boolean getDB (String dbName, String name, String pwd) {db = 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 String uname = MyPro are specified in the configuration file. getInstance (). getProperty ("uname"); String pwds = MyPro. getInstance (). getProperty ("password"); if (uname! = Null &&! "". Equals (uname) & pwds! = Null &&! "". Equals (pwds) {if (db. authenticate (uname, pwds. toCharArray () {return true;} else {return false ;}} return true ;} /*** close connection ** @ param mongo */public void closeAll (Mongo mongo) {if (mongo! = Null) {mongo. close () ;}}// you can use method overload to Transfer Parameters in different cases/*** obtain the specified set * @ param collectionName: the set to be linked * @ param dbName: database * @ return */public DBCollection getDBCollection (String collectionName, String dbName) {DBCollection dBCollection = null; if (getDB (dbName, null, null) {db. requestStart (); if (collectionName = null) {// if it is null, search for collectionName = MyPro in the configuration file. getInstance (). getProperty ("collectionName");} dBCollection = db. getCollection (collectionName);} else {// throw new RuntimeException ("database connection failed");} return dBCollection ;} /***** @ param collectionName * @ param dbName * @ param name * @ param password * @ return */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, search for collectionName = MyPro in the configuration file. getInstance (). getProperty ("collectionName");} dBCollection = db. getCollection (collectionName);} else {// throw new RuntimeException ("database connection failed");} return dBCollection ;} /*** only pass the set name * @ param collectionName * @ return */public DBCollection getDBCollection (String collectionName) {DBCollection dBCollection DBCollection = null; String dbName = MyPro. getInstance (). getProperty ("dbName"); if (getDB (dbName, null, null) {db. requestStart (); if (collectionName = null) {// if it is null, search for collectionName = MyPro in the configuration file. getInstance (). getProperty ("collectionName");} dBCollection = db. getCollection (collectionName);} else {// throw new RuntimeException ("database connection failed");} return dBCollection ;}

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