JavaWeb--MVC案例1-------（2）多个请求对应一个Servlet

1.编写继承了HttpServlet类的CustomerServlet类，并重写doGet()和doPost()方法

package MVCCases;

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.Method;

public class CustomerServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //super.doGet(req, resp);
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        //super.doPost(req, resp);

        //1.获取servletPath：/add.do 或 /delete.do等
        String servletPath = req.getServletPath();

        //2.取出/和.do得到方法名
        String methodName = servletPath.substring(1);
        methodName = methodName.substring(0, methodName.length() - 3);

        //3.利用反射获取methodName对应的方法
        Method method = null;
        try {

            method = getClass().getDeclaredMethod(methodName,
                    HttpServletRequest.class, HttpServletResponse.class);
            //4.利用发射调用对应的方法
            method.invoke(this, req, resp);

        } catch (Exception e) {
            e.printStackTrace();
　　　　　　　resp.sendRedirect("error.jsp");　
        }


    }

    private void add(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("add");
    }

    private void query(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("query");
    }

    private void delete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("delete");
    }
}

2.添加jsp和web.xml文件

<%--
  Created by IntelliJ IDEA.
  User: Skye
  Date: 2017/12/10
  Time: 11:10
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <a href="add.do">ADD</a>
    <br><br>

    <a href="query.do">QUERY</a>
    <br><br>

    <a href="delete.do">DELETE</a>
    <br><br>

</body>
</html>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">

    <servlet>
        <servlet-name>CustomerServlet</servlet-name>
        <servlet-class>MVCCases.CustomerServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>CustomerServlet</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>
</web-app>

3.编写CustomerServlet类，获取需要调用的方法，并利用反射获取并调用对应的方法