定义：
通用类图：
代理模式通用类图表示
/*
* 定义一个抽象的主题类
* */
public interface Subject {
// 定义一个方法
public void request();
}
public class RealSubject implements Subject {
@Override
public void request() {
// 定义具体的业务逻辑
}
}
/*
* 实现相关的代理类
* */
public class Proxy implements Subject {
private Subject subject;
public Proxy(Subject subject) {
this.subject = subject;
}
@Override
public void request() {
// TODO Auto-generated method stub
doBefore();
subject.request();
doAfter();
}
private void doBefore() {
}
private void doAfter() {
}
}
代理模式的优点：
代理模式的拓展：
- 普通代理模式(调用者知道代理的存在，同时知道代理的名字，但是不知道代理的是谁)：
普通代理模式类图
public interface IGamePlayer {
void login(String user, String password);
void killBoss();
void upgrade();
}
public class GamerProxy implements IGamePlayer {
private IGamePlayer gamePlayer = null;
public GamerProxy(String name) {
// TODO Auto-generated constructor stub
try {
gamePlayer = new GamerPlayer(this, name);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public void login(String user, String password) {
// TODO Auto-generated method stub
this.gamePlayer.login(user, password);
}
@Override
public void killBoss() {
// TODO Auto-generated method stub
this.gamePlayer.killBoss();
}
@Override
public void upgrade() {
// TODO Auto-generated method stub
this.gamePlayer.upgrade();
}
}
public class GamerPlayer implements IGamePlayer {
private String name = "";
public <T extends GamerProxy> GamerPlayer(T t, String name) throws Exception {
// TODO Auto-generated constructor stub
if (t == null) {
throw new Exception("不能创建对应的用户！");
} else {
this.name = name;
}
}
@Override
public void login(String user, String password) {
// TODO Auto-generated method stub
System.out.println(user + "" + name + "" + password);
}
@Override
public void killBoss() {
// TODO Auto-generated method stub
System.out.println(name + "killBoss");
}
@Override
public void upgrade() {
// TODO Auto-generated method stub
System.out.println(name + "upgrade");
}
}
- 强制代理模式（只能通过真实角色指定的代理类才能访问，也就是说由真实角色管理代理角色，即高层模块new了一个真实的对象，但是返回的确是代理角色）
强制代理模式类图
public interface IGamePlayer {
void login(String user, String password);
void killBoss();
void upgrade();
IGamePlayer getProxy();
}
public class GamerProxy implements IGamePlayer {
private IGamePlayer gamePlayer = null;
public <T extends GamerProxy> GamerProxy(GamerPlayer gamerPlayer) {
// TODO Auto-generated constructor stub
this.gamePlayer = gamePlayer;
}
@Override
public void login(String user, String password) {
// TODO Auto-generated method stub
this.gamePlayer.login(user, password);
}
@Override
public void killBoss() {
// TODO Auto-generated method stub
this.gamePlayer.killBoss();
}
@Override
public void upgrade() {
// TODO Auto-generated method stub
this.gamePlayer.upgrade();
}
@Override
public IGamePlayer getProxy() {
// TODO Auto-generated method stub
return this;
}
}
public class GamerPlayer implements IGamePlayer {
private String name = "";
private IGamePlayer proxy;
public GamerPlayer(String name) {
// TODO Auto-generated constructor stub
this.name = name;
}
@Override
public void login(String user, String password) {
// TODO Auto-generated method stub
if (isProxy()) {
System.out.println("login");
} else {
System.out.println("failed");
}
}
@Override
public void killBoss() {
}
@Override
public void upgrade() {
}
@Override
public IGamePlayer getProxy() {
this.proxy = new GamerProxy(this);
return this.proxy;
}
private boolean isProxy() {
if (this.proxy == null) {
return false;
} else {
return true;
}
}
}
public class Client {
public static void main(String[] args) {
IGamePlayer gamer = new GamerPlayer("zhangsan");
IGamePlayer gamerProxy = gamer.getProxy();
gamerProxy.login("", "");
}
}
- 增加接口整合不同的任务（图片少一个getProxy( )方法，参照上图）
多任务接口代理类整合
public interface IProxy {
// 计算费用
public void count();
}
public class GamerProxy implements IGamePlayer,IProxy {
private IGamePlayer gamePlayer = null;
public <T extends GamerProxy> GamerProxy(GamerPlayer gamerPlayer) {
// TODO Auto-generated constructor stub
this.gamePlayer = gamePlayer;
}
@Override
public void login(String user, String password) {
// TODO Auto-generated method stub
this.gamePlayer.login(user, password);
}
@Override
public void killBoss() {
// TODO Auto-generated method stub
this.gamePlayer.killBoss();
}
@Override
public void upgrade() {
// TODO Auto-generated method stub
this.gamePlayer.upgrade();
this.count();
}
@Override
public IGamePlayer getProxy() {
// TODO Auto-generated method stub
return this;
}
@Override
public void count() {
// TODO Auto-generated method stub
System.out.println("总费用");
}
}
- 动态代理：实现阶段不用关心代理谁，而在运行阶段才指定代理哪一个对象。（面向截面编程AOP的核心，被代理类实现必须实现）
动态代理模式通用类图
public interface IAdvice {
// 通知方法
public void exec();
}
public class BeforeAdvice implements IAdvice {
@Override
public void exec() {
// TODO Auto-generated method stub
System.out.println("前置通知");
}
}
public interface Subject {
// 业务操作
public void doSomething(String str);
}
public class ResultSubject implements Subject {
@Override
public void doSomething(String str) {
// TODO Auto-generated method stub
System.out.println("具体实际的操作方法");
}
}
public class DynamicProxy<T> {
public static <T> T newProxyInstance(ClassLoader loader,Class<?>[] interfaces,InvocationHandler h){
//寻找JoinPoint链接点，AOP框架使用元数据定义
if(true){
//执行前置通知
(new BeforeAdvice()).exec();
}
//执行目标，并返回结果
return (T)Proxy.newProxyInstance(loader, interfaces, h);
}
}
public class SubjectDynamicProxy extends DynamicProxy {//根据不同的主题进行二次封装
public static <T> T newProxyInstance(Subject subject){
//获取ClassLoader
ClassLoader loader = subject.getClass().getClassLoader();
//获取接口数据
Class<?>[] classes = subject.getClass().getInterfaces();
//获取handler
DemoInvocationHandler demoIH = new DemoInvocationHandler(subject);
return newProxyInstance(loader, classes, demoIH);
}
}
public class DemoInvocationHandler implements InvocationHandler {
// 被代理的对象
private Object target = null;
// 通过构造函数传递一个对象
public DemoInvocationHandler(Object object) {
// TODO Auto-generated constructor stub
this.target = object;
}
// 代理方法
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
// TODO Auto-generated method stub
// 被代理的方法
return method.invoke(this.target, args);
}
}
public class Client {//两种方式
public static void main(String[] args) {
// 定义主题
Subject subject = new ResultSubject();
// 定义主题代理类
Subject proxy = SubjectDynamicProxy.newProxyInstance(subject);
proxy.doSomething("");
///////////////////////////////////////
// 定义主题
Subject subjectTwo = new ResultSubject();
// 定义handler
InvocationHandler iH = new DemoInvocationHandler(subjectTwo);
// 定义主题代理类
Subject proxyTwo = DynamicProxy.newProxyInstance(subjectTwo.getClass().getClassLoader(),
subjectTwo.getClass().getInterfaces(), iH);
proxyTwo.doSomething("");
}
}
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