java中的動態代理

package DynamicProxy;

public interface IUserDao {
	public void judge(String userId);
}




package DynamicProxy;

public class UserDaoImpl implements IUserDao{

	public UserDaoImpl() {
	}

	@Override
	public void judge(String userId) {
		if("1".equals(userId)){
			System.out.println("the userId is 1");
		}else {
			System.out.println("the userId is not 1");
		}
	}

}










package DynamicProxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DaoHandler implements InvocationHandler{

	private Object object;
	
	public DaoHandler() {
	}

	public DaoHandler(Object object) {
		this.object = object;
	}
	@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		
		beforeInvoke();
		Object result = method.invoke(object, args);
		afterInvoke();
		return null;
	}

	private void afterInvoke() {
		
		System.out.println("after");
		
	}

	private void beforeInvoke() {
		
		System.out.println("before");
		
	}

}








package DynamicProxy;

import java.lang.reflect.Proxy;

public class TestMain {

	public TestMain() {
		
	}
	
	public static void main(String[] args) {
		
		
		IUserDao userDao = new UserDaoImpl();
		
		DaoHandler handler = new DaoHandler(userDao);
		
		//創建代理
		IUserDao userDao2  = (IUserDao)Proxy.newProxyInstance(userDao.getClass().getClassLoader(), new Class[]{IUserDao.class}, handler);
		
//		System.out.println(userDao2);
		
		userDao2.judge("1");
		
	}

}