代理模式

代理模式 實現(xiàn)邏輯和實現(xiàn)的解耦

代理模式 為了提供額外的的操作，插入用來代替實際對象的對象。這些操作通常涉及與實際對象通信，代理充當中間人的角色

• 接口

/**
 * 接口
 */
public interface Interface {
    void doSomething();
    void somethingElse(String arg);
}

• 實際對象

/**
 * 實際對象
 */
public class RealObject implements Interface {
    public void doSomething() {
        System.out.println("doSomething");
    }

    public void somethingElse(String arg) {
        System.out.println("somethingElse" + arg);
    }
}

• 代理對象

/**
 * 代理對象
 */
public class Proxy implements Interface {
    private Interface proxied;

    public Proxy(Interface proxied) {
        this.proxied = proxied;
    }

    public void doSomething() {
        System.out.println("Proxy doSomething");
        proxied.doSomething();
    }

    public void somethingElse(String arg) {
        System.out.println("Proxy somethingElse" + arg);
        proxied.somethingElse(arg);
    }
}

• 測試

    /**
     * 測試代理，比較原對象與代理對象
     *
     * @param args
     */
    public static void main(String[] args) {
        Interface iface = new RealObject();
        iface.doSomething();
        iface.somethingElse("bonobo");

        Interface iface2 = new Proxy(iface);
        iface2.doSomething();
        iface2.somethingElse("bonobo");
    }

動態(tài)代理

Java動態(tài)代理可以動態(tài)創(chuàng)建代理并動態(tài)處理對所代理的方法的調(diào)用

在動態(tài)里上所做的所有調(diào)用都會被重定向到單一的調(diào)用處理器上，它的工作是揭示調(diào)用的類型并確定對應的對策

• 動態(tài)代理

public class DynamicProxyHandler implements InvocationHandler {
    private Object proxied;

    public DynamicProxyHandler(Object proxied) {
        this.proxied = proxied;
    }

    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println("**** proxy:" + proxy.getClass() + ".method: " + method + ".args: " + args);
        if (args != null) {
            for (Object arg : args) {
                System.out.println("    " + args);
            }
        }
        return method.invoke(proxied, args);
    }
}

• 測試

    public static void main(String[] args){
        RealObject real = new RealObject();
        real.doSomething();
        real.somethingElse("bonobo");

        Interface proxy = (Interface) Proxy.newProxyInstance(
                Interface.class.getClassLoader(),
                new Class[]{Interface.class},
                new DynamicProxyHandler(real));
        proxy.doSomething();
        proxy.somethingElse("bonobo");

    }