MVC案例——问题一：多个请求使用一个servlet
方法一：
CustomerServlet
package com.mvcapp.servlet;
import com.sun.net.httpserver.HttpServer;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CustomerServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String method = req.getParameter("method");
switch (method){
case "add": add(req,resp);break;
case "delete": delete(req,resp);break;
case "update": update(req,resp);break;
}
}
private void add(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("add");
}
private void delete(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("delete");
}
private void update(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("update");
}
}
JSP代码
<%--
Created by IntelliJ IDEA.
User: dell
Date: 2019/7/4
Time: 17:23
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="CustomerServlet?method=add">ADD</a>
<br>
<a href="CustomerServlet?method=update">UPDATE</a>
<br>
<a href="CustomerServlet?method=delete">DELETE</a>
</body>
</html>
注册servlet代码：
<servlet>
<servlet-name>CustomerServlet</servlet-name>
<servlet-class>com.mvcapp.servlet.CustomerServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CustomerServlet</servlet-name>
<url-pattern>/CustomerServlet</url-pattern>
</servlet-mapping>
问题：
1.当添加一个请求时，需要在Servlet中修改两处的代码：switch、添加方法
2.url中使用method=xxx暴漏了要调用的方法，不私密，有安全隐患。
方法二：
CustomerServlet
package com.mvcapp.servlet;
import com.sun.net.httpserver.HttpServer;
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 {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String servletPath = req.getServletPath();
String methodName = servletPath.substring(1,servletPath.length()-3);
Method method = null;
try {
method = getClass().getDeclaredMethod(methodName,HttpServletRequest.class,HttpServletResponse.class);
method.invoke(this,req,resp);
} catch (Exception e) {
e.printStackTrace();
}
}
private void add(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("add");
}
private void delete(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("delete");
}
private void update(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("update");
}
}
web.xml
<servlet>
<description></description>
<display-name>CustomerServlet</display-name>
<servlet-name>CustomerServlet</servlet-name>
<servlet-class>com.mvcapp.servlet.CustomerServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CustomerServlet</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<a href="add.do">ADD</a>
<br>
<a href="update.do">UPDATE</a>
<br>
<a href="delete.do">DELETE</a>
</body>
</html>
