如何在Java中实现代理模式，静态代理和动态代理有什么区别？

// 接口
public interface Service {
    void doSomething();
}

// 目标类
public class RealService implements Service {
    public void doSomething() {
        System.out.println("做点实际的事");
    }
}

// 代理类
public class StaticProxy implements Service {
    private Service target;

    public StaticProxy(Service target) {
        this.target = target;
    }

    public void doSomething() {
        System.out.println("前置处理");
        target.doSomething();
        System.out.println("后置处理");
    }
}

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class JdkDynamicProxyExample {
    public static void main(String[] args) {
        RealService realService = new RealService();

        Service proxyInstance = (Service) Proxy.newProxyInstance(
            realService.getClass().getClassLoader(),
            new Class[]{Service.class},
            new InvocationHandler() {
                public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                    System.out.println("JDK动态代理 - 前置处理");
                    Object result = method.invoke(realService, args);
                    System.out.println("JDK动态代理 - 后置处理");
                    return result;
                }
            }
        );

        proxyInstance.doSomething();
    }
}