SpringJDK动态代理实现，2024Java面试真题精选干货整理

package com.Keafmd.spring5;
/**
• Keafmd
• 
• @ClassName: UserDao
• @Description:
• @author: 牛哄哄的柯南
• @date: 2021-01-17 20:41
*/
public interface UserDao {
public int add(int a,int b);
public String updat(String id);
}

package com.Keafmd.spring5;
/**
• Keafmd
• 
• @ClassName: UserDaoImpl
• @Description: 实现类
• @author: 牛哄哄的柯南
• @date: 2021-01-17 20:42
*/
public class UserDaoImpl implements UserDao{
@Override
public int add(int a, int b) {
System.out.println(“add执行中…”);
return a+b;
}
@Override
public String updat(String id) {
System.out.println(“updat执行中…”);
return id;
}
}

package com.Keafmd.spring5;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
/**
• Keafmd
• 
• @ClassName: JDKProxy
• @Description:
• @author: 牛哄哄的柯南
• @date: 2021-01-17 20:44
*/
public class JDKProxy {
public static void main(String[] args) {
//创建接口实现类代理对象
Class[] interfaces = {UserDao.class};
/*Proxy.newProxyInstance(JDKProxy.class.getClassLoader(), interfaces, new InvocationHandler() {
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
return null;
}
});*/
UserDaoImpl userDao = new UserDaoImpl();
UserDao dao = (UserDao) Proxy.newProxyInstance(JDKProxy.class.getClassLoader(), interfaces, new UserDaoProxy(userDao));
System.out.println(“-----------对add方法进行增强----------”);
int result = dao.add(1, 2);