自己为了测试servlet，用MyEclipse2015写了一个简单的登录程序。
1.登录页面index.jsp.
1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 2 <% 3 String lUserName = (String)session.getAttribute("iUserName"); 4 %> 5 6 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 7 <html> 8 <head> 9 <meta charset="utf-8"> 10 <title>My JSP 'index.jsp' starting page</title> 11 <meta http-equiv="pragma" content="no-cache"> 12 <meta http-equiv="cache-control" content="no-cache"> 13 <meta http-equiv="expires" content="0"> 14 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 15 <meta http-equiv="description" content="This is my page"> 16 </head> 17 18 <body> 19 <% 20 if (lUserName != ""&&lUserName!=null) { 21 %> 22 欢迎光临，<%=lUserName%> 23 <% 24 } else { 25 %> 26 <form name="loginfrm" action="loginserv" method="post"> 27 用户名：<input type="text" name="username" value="zhangsan"><br> 28 密码:<input type="text" name="password" value="mm123456"><br> 29 <input type="submit" value="登录"> 30 </form> 31 <% 32 } 33 %> 34 </body> 35 </html>
2.用模版写了一个servlet程序loginserv.java.
1 package com.kaly.servlet; 2 3 import java.io.IOException; 4 import java.io.PrintWriter; 5 6 import javax.servlet.ServletException; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse; 10 11 public class loginserv extends HttpServlet { 12 public void doGet(HttpServletRequest request, HttpServletResponse response) 13 throws ServletException, IOException { 14 doPost(request, response); 15 } 16 17 public void doPost(HttpServletRequest request, HttpServletResponse response) 18 throws ServletException, IOException { 19 request.setCharacterEncoding("utf-8"); 20 response.setContentType("text/html);charset=utf-8"); 21 String getUser=request.getParameter("username"); 22 String getpassword=request.getParameter("password"); 23 PrintWriter pw=response.getWriter(); 24 pw.print(getUser); 25 } 26 27 }
这是一个很简单的程序，在收到请求后，把用户名打印出来。
3.运行出现问题：The requested resource is not available.
4.查找咨询，没有解决。后来查看web.xml。
1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app version="3.0" 3 xmlns="http://java.sun.com/xml/ns/javaee" 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 5 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> 6 <servlet> 7 <description>This is the description of my J2EE component</description> 8 <display-name>This is the display name of my J2EE component</display-name> 9 <servlet-name>loginserv</servlet-name> 10 <servlet-class>com.kaly.servlet.loginserv</servlet-class> 11 </servlet> 12 13 <servlet-mapping> 14 <servlet-name>loginserv</servlet-name> 15 <url-pattern>/servlet/loginserv</url-pattern> 16 </servlet-mapping> 17 18 </web-app>
因为这些都是自动生成，没有想到过会出现问题。不过记起以前写这个程序时<url-pattern>节点只是在<servlet-name>节点内容前多一个"/"，尝试将其改为/loginserv，重启服务运行页面。一些正常。
总结：这应该是这种问题出现的其中一种解决途径。