Several ways to enhance a method in a Java class

 

* One way: the way of inheritance .

* inheritance can only be used when it is possible to control the construction of this class .

Connection is an interface that implements classes that are not deterministic ( provided by each vendor ) and cannot use this method

* two ways: decorator mode .

* Both the wrapper object and the wrapped object are to implement the same interface .

* The Wrapper object needs to get a reference to the wrapped object .

Disadvantage: If the interface method is more , enhance one of the methods . other functions of the method require the original call .

* three ways: dynamic proxy mode .

* The Enhanced object implementation interface is available .

"case of the successor and decorator"

/**

* inherited ways to enhance a method in a class :

*/

Class man{

public void Run () {

System.out.println (" Run .... ");

}

}

Class Superman extends man{

public void Run () {

Super.run ();

System.out.println (" Fly ....");

}

}

/**

* enhancements to the method of completing the class using the Decorator's way

*/

Interface waiter{

public void Server ();

}

Class Waiteress implements waiter{

@Override

public void Server () {

System.out.println (" service ...");

}

}

Class Waiteresswrapper implements waiter{

Private Waiter waiter;

Public Waiteresswrapper (waiter Waiter) {

This.waiter = waiter;

}

@Override

public void Server () {

System.out.println (" Smile ...");

This.waiter.server ();

}

}

"use decorator mode to enhance Connection 's close method "

public class MyConnection implements connection{

Private Connection conn;

Private List<connection> List;

Public myconnection (Connection conn,list<connection> List) {

This.conn = conn;

This.list = list;

}

@Override

public void Close () throws SQLException {

List.add (conn);

}
...

}

Getconnection method for connection pooling :
@Override

how to get connected:

Public Connection getconnection () throws SQLException {

If (list.size () <= 0) {

For (int I=1;i<=3;i++) {

Connection conn = Jdbcutils.getconnection ();

List.add (conn);

}

}

Connection conn = List.remove (0);

MyConnection myconn = new MyConnection (conn, list);

Return myconn;

}

Several ways to enhance a method in a Java class