[Java EE] database connection pool and dynamic proxy

Implementing the Javax.sql.DataSource interface

Implementing the Connection getconnection () method

Defines a static member property LinkedList type as a connection pool, initializes 5 database connections in a static code block, adds to the connection pool, and getconnection method, remove a connection from the connection pool when you get the connection.

ImportJava.lang.reflect.InvocationHandler;ImportJava.lang.reflect.Method;ImportJava.lang.reflect.Proxy;Importjava.sql.Connection;ImportJava.sql.ResultSet;Importjava.sql.Statement; Public classJdbctest { Public Static voidMain (string[] args)throwsException {//How to use reflectionClass.forName ("Com.mysql.jdbc.Driver"); //to get the database connection, when the guide packet, attention to guide java.sql, interface-oriented programmingMypool pool=NewMypool (); Connection Conn=pool.getconnection (); //get The transmitter objectStatement statement=conn.createstatement (); //get result Set objectResultSet resultset=statement.executequery ("SELECT * from User"); //Traverse         while(Resultset.next ()) {String username=resultset.getstring ("username");        SYSTEM.OUT.PRINTLN (username); }        //Close ResourceResultset.close ();        Statement.close ();            POOL.RESETCONN (conn); }}

My connection Pool

ImportJava.io.PrintWriter;Importjava.sql.Connection;ImportJava.sql.DriverManager;Importjava.sql.SQLException;Importjava.sql.SQLFeatureNotSupportedException;Importjava.util.LinkedList;Importjava.util.List;ImportJava.util.logging.Logger;ImportJavax.sql.DataSource;/*** Handwritten connection pool * *@authorTaoshihan **/ Public classMypoolImplementsDataSource {//Connection Pool     Public StaticList<connection> pool =NewLinkedlist<connection>(); //Initialize    Static {        Try{class.forname ("Com.mysql.jdbc.Driver");  for(inti = 0; I < 5; i++) {Connection conn=Drivermanager.getconnection ("Jdbc:mysql://localhost:3306/java", "root", "root");            POOL.ADD (conn); }        } Catch(Exception e) {}}/*** Get Connections*/@Override PublicConnection getconnection ()throwsSQLException {//If there is no connection in the pool        if(pool.size () = = 0) {             for(inti = 0; I < 5; i++) {Connection conn=Drivermanager.getconnection ("Jdbc:mysql://localhost:3306/java", "root", "root");            POOL.ADD (conn); }        }        //Advanced First OutConnection Conn=pool.remove (0); System.out.println ("Get a connection, the pool is still remaining" +pool.size ()); returnConn; }    /*** Reset Connection*/     Public voidResetconn (Connection conn) {Try {            if(conn!=NULL&&!conn.isclosed ())                {POOL.ADD (conn); System.out.println ("Also back a connection, the pool is still remaining" +pool.size ()); }        } Catch(Exception e) {e.printstacktrace (); }} @Override PublicConnection getconnection (string Username, string password)throwsSQLException {return NULL; } @Override PublicPrintWriter Getlogwriter ()throwsSQLException {//TODO auto-generated Method Stub        return NULL; } @Override Public voidSetlogwriter (PrintWriter out)throwsSQLException {//TODO auto-generated Method Stub} @Override Public voidsetLoginTimeout (intSecondsthrowsSQLException {//TODO auto-generated Method Stub} @Override Public intGetlogintimeout ()throwsSQLException {//TODO auto-generated Method Stub        return0; } @Override PublicLogger Getparentlogger ()throwssqlfeaturenotsupportedexception {//TODO auto-generated Method Stub        return NULL; } @Override Public<T> T Unwrap (class<t> iface)throwsSQLException {//TODO auto-generated Method Stub        return NULL; } @Override Public BooleanIswrapperfor (class<?> iface)throwsSQLException {//TODO auto-generated Method Stub        return false; }}

Using inheritance, decoration, dynamic agents to transform methods in a class

The disadvantage of inheritance: At this point we have got the Connection object, so we cannot transform this object through inheritance

The test implementation of the decoration:

ImportJava.lang.reflect.InvocationHandler;ImportJava.lang.reflect.Method;ImportJava.lang.reflect.Proxy;Importjava.sql.Connection;ImportJava.sql.ResultSet;Importjava.sql.Statement; Public classJdbctest { Public Static voidMain (string[] args)throwsException {//Test Decorating ModeAnimal dog=NewBigDog (NewDog ());        Dog.eat ();    Dog.sound (); }}/*** Decoration Mode test *@authorTaoshihan **/Interfaceanimal{ Public voideat ();  Public voidSound ();}classDogImplementsanimal{@Override Public voideat () {System.out.println (Eat); } @Override Public voidSound () {System.out.println (Wang); }}//at this point I want to modify the sound method in the dog classclassBigDogImplementsanimal{PrivateDog Dog;  PublicBigDog (dog dog) { This. dog=Dog; }    /*** This method to tune the original*/@Override Public voideat () {dog.eat (); }    /*** This method is decorated*/@Override Public voidSound () {System.out.println (Shout); }    }

Dynamic Agent:

                //Test agent Mode        FinalDog dog=NewDog (); Animal Proxy= (Animal) proxy.newproxyinstance (Dog.class. getClassLoader (), Dog.class. Getinterfaces (),NewInvocationhandler () {@Override Publicobject Invoke (Object proxy, Method method, object[] args)throwsThrowable {if("Sound". Equals (Method.getname ())) {System.out.println (Shout); return NULL; }Else{                    returnMethod.invoke (dog, args);        }            }        });        Proxy.eat (); Proxy.sound ();

[Java EE] database connection pool and dynamic proxy