JAVA-Proxy 代理

jdk静态代理

interface Dao {
    void save();
}
class DaoImpl implements Dao {
    @Override
    public void save() {
        System.out.println("save...");
    }
}
class DaoProxy implements Dao{
    private Dao target;

    public DaoProxy(Dao target) {
        this.target = target;
    }

    @Override
    public void save() {
        System.out.println("before...");
        target.save();
        System.out.println("after...");
    }
}

public class StaticProxyTest {
    public static void main(String[] args) {
        DaoImpl target = new DaoImpl();
        Dao userDao = new DaoProxy(target);
        userDao.save();
    }
}

jdk动态代理(代理接口)

interface Dao {
    void save();
}
class DaoImpl implements Dao {
    @Override
    public void save() {
        System.out.println("save...");
    }
}
public class DynamicProxyTest {
    public static void main(String[] args) {
        Object target = new DaoImpl();
        /**
         * loader：业务对象的类加载器
         * interfaces：业务对象实现的所有的接口，可直接指定业务类实现的接口 Class[]
         * h：InvocationHandler 对象，最终由它调用业务对象的方法
         * public static Object newProxyInstance(ClassLoader loader, Class<?>[] interfaces, InvocationHandler h)
         */
        Dao dao = (Dao) Proxy.newProxyInstance(DaoImpl.class.getClassLoader(), new Class<?>[]{Dao.class}, new InvocationHandler() {
            /**
             * @param proxy 代理对象
             * @param method 代理的方法对象
             * @param args 方法调用时参数
             */
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                Object result = null;
                if (method.getName().equals("save")) {
                    System.out.println("before...");
                    result = method.invoke(target, args);
                    System.out.println("after...");
                }
                return result;
            }
        });
        dao.save();
    }
}

cglib代理(代理类)

public class Dao {
    public void select() {
        System.out.println("select()");
    }
}

public class DaoProxy implements MethodInterceptor {
    /**
     * @param object 要进行增强的对象
     * @param method 拦截的方法
     * @param objects 参数列表，基本数据类型需要传入其包装类型
     * @param proxy 对方法的代理，invokeSuper 方法表示对被代理对象方法的调用
     */
    @Override
    public Object intercept(Object object, Method method, Object[] objects, MethodProxy proxy) throws Throwable {
        System.out.println("Before Method Invoke");
        proxy.invokeSuper(object, objects);
        System.out.println("After Method Invoke");

        return object;
    }
}

public static void main(String[] args) {
    DaoProxy daoProxy = new DaoProxy();

    Enhancer enhancer = new Enhancer();
    enhancer.setSuperclass(Dao.class);
    enhancer.setCallback(daoProxy);

    Dao dao = (Dao) enhancer.create();
    dao.select();
}