動態(tài)代理

第一步：實現(xiàn)鋼筆接口

interface PenInterface {

    void write();

    void draw();

}

第二步：學(xué)生的手實現(xiàn)鋼筆接口

public class StudentHand implements PenInterface {

    @Override
    public void write() {
        System.out.println("學(xué)生用筆寫字");

    }

    @Override
    public void draw() {
        System.out.println("學(xué)生用筆畫畫");
    }

}

第三步：學(xué)生代理的功能

public class StudentProxy implements InvocationHandler {

    private Object mTarget;

    public StudentProxy(Object target) {
        mTarget = target;
    }

    public Object getInstance() {
        return Proxy.newProxyInstance(mTarget.getClass().getClassLoader(), mTarget.getClass().getInterfaces(), this);
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        doSthBefore();
        Object object = method.invoke(mTarget, args);
        doSthAfter();
        return object;
    }

    private void doSthBefore() {
        System.out.println("調(diào)用方法之前");
    }

    private void doSthAfter() {
        System.out.println("調(diào)用方法之后");
    }

}

最后：通過學(xué)生去動態(tài)實現(xiàn)相關(guān)功能

public static void main(String[] args) {
    PenInterface penInterface = new StudentHand();
    PenInterface student = (PenInterface) new StudentProxy(penInterface).getInstance();
    student.draw();
    //student.write();
}