一个servlet处理多个请求（使用Method的反射机制）

方法一

可以通过在请求的时候加上参数，然后在servlet中获取请求的参数，再去调用对应的方法。达到一个servlet处理多个请求的目的

test.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'test.jsp' starting page</title>
</head>
<body>
<!--
请求的时候加上对应的请求参数
-->
    <a href="customerServlet?method=add"> Add</a>
    <br>
    <br>
    <a href="customerServlet?method=query"> Query</a>
    <br>
    <br>
    <a href="customerServlet?method=delete"> Delete</a>
</body>
</html>

CustomerServlet.Java:

package com.aaa.mvcapp.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CustomerServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //获取对应的请求参数
        String method = request.getParameter("method");
        //根据请求参数去调用对应的方法。
        if ("add".equals(method)) {
            add(request, response);

        } else if ("query".equals(method)) {
            query(request, response);
        }

        else if ("delete".equals(method)) {
            delete(request, response);
        }
    }

    private void delete(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("delete");

    }

    private void query(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("query");
    }

    private void add(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("add");

    }
}

方法二

1.在servlet的mapping中配置为 *.do来响应多个请求 
2. 在servlet中获取servletPath。（例如/=add.do） 
3. 去除/ 和.do，利用反射再去调用对应的方法。

web.xml(servlet配置):

  <servlet>
    <servlet-name>CustomerServlet</servlet-name>
    <servlet-class>com.aaa.mvcapp.servlet.CustomerServlet</servlet-class>
  </servlet>

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

test.jsp:

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'test.jsp' starting page</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>
</body>
</html>

CustomerServlet.java:

package com.aaa.mvcapp.servlet;

import java.io.IOException;
import java.lang.reflect.Method;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CustomerServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        // 获取方法名字
        String servletPath = request.getServletPath();// /xxxxxx.do
        // 去掉斜杠和.do
        String methodName = servletPath.substring(1, servletPath.length() - 3);// xxxxxx

        try {
            // 利用反射获取方法
            Method method = getClass().getDeclaredMethod(methodName,
                    HttpServletRequest.class, HttpServletResponse.class);
            // 执行相应的方法
            method.invoke(this, request, response);
        } catch (Exception e) {
            // TODO: handle exception
        }
    }

    private void delete(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("delete");

    }

    private void query(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("query");
    }

    private void add(HttpServletRequest request, HttpServletResponse response) {
        // TODO Auto-generated method stub
        System.out.println("add");

    }
}

这样一来不同的请求可以会用同一个servlet来处理，在servlet内部为不同的请求分别有不同的方法去处理。