Java design Pattern: Single state mode, Factory mode, Agent mode, observer mode sample __java

Single State mode

It is not strange that public class Singleton {private Singleton () {}//define yourself an instance within yourself. Note that this is private only for internal calls private static Singleton instance = new Singleton (); This provides a static method for accessing this class externally, and you can access the public static Singleton getinstance () {return instance} directly.

Factory mode

Package com; Products Interface interface Product {public void GetName ();}//Specific product A class ProductA implements product {public void GetName () {S Ystem.out.println ("I am ProductA");} Specific product B class PRODUCTB implements product {public void GetName () {System.out.println ("I am ProductB");} Factory class public class Productcreator {public Product createproduct (String type) {if (' A '. Equals (type)) {return new Prod Ucta (); } if ("B". Equals (Type)) {return new PRODUCTB ();} else return null; public static void Main (string[] args) {Productcreator creator = new Productcreator (); Creator.createproduct ("A") Name (); Creator.createproduct ("B"). GetName ();}

Agent Mode 1

Import Java.lang.reflect.InvocationHandler; Import Java.lang.reflect.Method; Import Java.lang.reflect.Proxy; public class Proxytest {public static void main (string[] args) {Salecomputer salecomputer = new Computermaker (); Invocationhandler handler = new Saleproxy (salecomputer); Salecomputer proxy = (salecomputer) proxy.newproxyinstance (Salecomputer.getclass (). getClassLoader (), Salecomputer.getclass (). Getinterfaces (), handler); Proxy.salecomputer ("Floral"); } interface salecomputer{//selling computer public void Salecomputer (String type);} class Computermaker implements salecomputer{Pu Blic void Salecomputer (String type) {System.out.println ("sell a" + type + "Brand computer.) "); } } Class Saleproxy implements invocationhandler{Object delegate; public Saleproxy (object delegate) {this.delegate = Delegat E public object invoke (object proxy, Method method, object[] args) throws Throwable {Givemouse (); return Method.invoke (DE Legate,args); private void Givemouse () {System.out.println ("Send mouse .... ..."); ".}}

Agent Mode 2

public class ProxyTest1 {public static void main (string[] args) {SaleComputer1 salecomputer = new ComputerMaker1 (); SaleComputer1 proxy = new SaleProxy1 (salecomputer); Proxy.salecomputer ("Hung Run"); } interface salecomputer1{//interface public void Salecomputer (String type);} class ComputerMaker1 implements salecomputer1{/ /implementation class public void Salecomputer (String type) {System.out.println ("sell a" + type + "Brand computer.) "); } } Class SaleProxy1 implements salecomputer1{/proxy class SaleComputer1 delegate; public SaleProxy1 (Object delegate) { This.delegate = (SaleComputer1) delegate; public void Salecomputer (String type) {This.givemouse (); Delegate.salecomputer (type);} private void Givemouse () {Syste M.OUT.PRINTLN ("Send the mouse .... ..."); ".}

Observer mode:

Package Com.model; Import java.util.Observable; Import Java.util.Observer; The/** Java API provides us with observer interfaces and observable classes to implement the so-called observer pattern. The observable (Observer) class allows you to notify other objects (Implementation interface Observer, observer) when changes occur to them. */public class testobserver{public static void Main (string[] args) {Produce produce = new produce (); Nameobserver nameobserver = new Nameobserver (); Priceobserver priceobserver = new Priceobserver (); Produce.addobserver (Nameobserver); Produce.addobserver (Priceobserver); Produce.setname ("Apple"); Produce.setprice (100); }///An observable class produce extends observable{private string name, private Integer price, public string GetName () {retur n Name; public void SetName (String name) {this.name = name; setchanged ();//Set Change point notifyobservers (name);//Notify Observer} public Integ Er getprice () {return price} public void Setprice (Integer price) {this.price = Price; setchanged (); Notifyobservers (pr ICE); }///Two Observer class Nameobserver implements observer{public void update (observable o, Object Arg) {if (arg instanceofString) {System.out.println ("observed by Observer: Product name changed to:" + arg);}}} Class Priceobserver implements observer{public void update (observable o, Object Arg) {if (arg instanceof Integer) {System . OUT.PRINTLN ("observed by the Observer: The price has been changed to:" + arg);}}