1.<a href="customerServlet?method=add">Add</a> 这里method=add不能有空格,否则报错(空指针异常)
1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1" 2 pageEncoding="ISO-8859-1"%> 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 4 <html> 5 <head> 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 7 <title>Insert title here</title> 8 </head> 9 <body> 10 <a href="customerServlet?method=add">Add</a> 11 <br> 12 <br> 13 14 <a href="customerServlet?method=query">Query</a> 15 <br> 16 <br> 17 18 <a href="customerServlet?method=delete">Delete</a> 19 <br> 20 <br> 21 22 </body> 23 </html>
1 package com.ouyang.dao; 2 3 import java.io.IOException; 4 5 import javax.servlet.ServletException; 6 import javax.servlet.annotation.WebServlet; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse; 10 11 @WebServlet("/customerServlet") 12 public class CustomerServlet extends HttpServlet { 13 private static final long serialVersionUID = 1L; 14 15 protected void doGet(HttpServletRequest request, 16 HttpServletResponse response) throws ServletException, IOException { 17 doPost(request, response); 18 } 19 20 protected void doPost(HttpServletRequest request, 21 HttpServletResponse response) throws ServletException, IOException { 22 String method = request.getParameter("method"); 23 24 switch (method) { 25 case "add": 26 add(request, response); 27 break; 28 case "query": 29 query(request, response); 30 break; 31 case "delete": 32 delete(request, response); 33 break; 34 35 } 36 37 } 38 39 private void delete(HttpServletRequest request, HttpServletResponse response) 40 throws ServletException, IOException { 41 System.out.println("delete"); 42 } 43 44 private void query(HttpServletRequest request, HttpServletResponse response) 45 throws ServletException, IOException { 46 System.out.println("query"); 47 } 48 49 private void add(HttpServletRequest request, HttpServletResponse response) 50 throws ServletException, IOException { 51 System.out.println("add"); 52 53 } 54 55 }
2.url-pattern 中在建立Servlet时前面不应该加"/".否则会报错