利用反射重构 Servlet

BaseServlet

package com.cn;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class BaseServlet extends HttpServlet {

    @Override
    public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //根据请求的uri获取对应的请求方法 然后在执行对应的方法即可
        String requestURI = request.getRequestURI();
        int i = requestURI.lastIndexOf("/")+1;
        String method = requestURI.substring(i);   //@WebServlet("/userServlet/*")  这样就从uri中获取到了需要执行的方法

        // this 就是 com.cn.UserServlet@78d81ec1   //public class UserServlet extends BaseServlet {}
        //System.out.println(this);
        Class clazz = this.getClass();
        //获取字节码中所有的方法
        try {
            Method m = clazz.getMethod(method,HttpServletRequest.class,HttpServletResponse.class);
            m.invoke(this,request,response);

        } catch (Exception e) {
            e.printStackTrace();
        }


    }
}

Servlet

@WebServlet("/userServlet/*")
public class UserServlet extends BaseServlet {

    public void hello(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("我是hello的方法");
    }


}

//启动测试 调用Hello方法

http://localhost:8080/Re_Servlet/userServlet/hello