代理代理，就是找個(gè)人代替你做你該做的事，分為靜態(tài)代理和動(dòng)態(tài)代理，一個(gè)一個(gè)說(shuō)

準(zhǔn)備工作

我們先假設(shè)一種場(chǎng)景，打游戲，我們創(chuàng)建一個(gè)游戲人物去打游戲，讓一個(gè)代理幫我們打游戲
1，建立一個(gè)游戲人物的抽象類

public interface GamePlayer {
    void login(String user,String password);
    void killBoss();
    void upgrade();
}

2，游戲人物的實(shí)體類

public class GamePlayerA implements GamePlayer{

    private String name;

    public GamePlayerA(String name){
        this.name = name;
    }


    @Override
    public void login(String user, String password) {
        System.out.println(name + " 登錄成功" + " 登錄名為" + user);
    }

    @Override
    public void killBoss() {
        System.out.println(this.name + "在打怪");
    }

    @Override
    public void upgrade() {
        System.out.println(this.name + "恭喜你 升級(jí)了");
    }
}

下面開(kāi)始實(shí)現(xiàn)代理

靜態(tài)代理

靜態(tài)代理是在編譯時(shí)期就把代理實(shí)現(xiàn)了
1，將被代理對(duì)象構(gòu)造注入，代碼如下

public class GamePlayerProxy implements GamePlayer{

    private GamePlayer gamePlayer;

    public GamePlayerProxy(GamePlayer gamePlayer){
        this.gamePlayer = gamePlayer;
    }

    @Override
    public void login(String user, String password) {
        this.gamePlayer.login(user,password);
    }

    @Override
    public void killBoss() {
        this.gamePlayer.killBoss();
    }

    @Override
    public void upgrade() {
        this.gamePlayer.upgrade();
    }
}

2，調(diào)用

public class Main {
    public static void main(String[] args){
        GamePlayer gamePlayer = new GamePlayerA("張三");
        GamePlayerProxy gamePlayerProxy = new GamePlayerProxy(gamePlayer);
        gamePlayerProxy.login("zhangsan","password");
        gamePlayerProxy.killBoss();
        gamePlayerProxy.upgrade();
    }
}

還是挺簡(jiǎn)單的，就是把被代理對(duì)象構(gòu)造注入，然后在內(nèi)部調(diào)用被代理對(duì)象，這里我們可以做的更極致一點(diǎn)就是把被代理對(duì)象都隱藏起來(lái)讓高層組件只能接觸到代理對(duì)象

動(dòng)態(tài)代理

在運(yùn)行時(shí)創(chuàng)建代理類，這里要注意我們使用java中的動(dòng)態(tài)代理實(shí)際上就是創(chuàng)建了在運(yùn)行時(shí)動(dòng)態(tài)創(chuàng)建了一個(gè)

public class Main {
    public static void main(String[] args){
        GamePlayer gamePlayer = new GamePlayerA("張三");
        GamePlayer gamePlayerProxy = (GamePlayer) Proxy.newProxyInstance(gamePlayer.getClass().getClassLoader(),
                gamePlayer.getClass().getInterfaces(),
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        return method.invoke(gamePlayer,args);
                    }
                });
        gamePlayerProxy.login("zhangsan","password");
        gamePlayerProxy.killBoss();
        gamePlayerProxy.upgrade();
    }
}

我們?cè)谑褂玫臅r(shí)候大部分都是使用的動(dòng)態(tài)代理，通過(guò)反射調(diào)用目標(biāo)方法，在代理中增加非業(yè)務(wù)性代碼，比如打點(diǎn)啊，數(shù)據(jù)統(tǒng)計(jì)之類的