自己為了測試servlet，用MyEclipse2015寫了一個簡單的登錄程序。
1.登錄頁面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 歡迎光臨，<%=lUserName%> 23 <% 24 } else { 25 %> 26 <form name="loginfrm" action="loginserv" method="post"> 27 用戶名：<input type="text" name="username" value="zhangsan"><br> 28 密碼:<input type="text" name="password" value="mm123456"><br> 29 <input type="submit" value="登錄"> 30 </form> 31 <% 32 } 33 %> 34 </body> 35 </html>
2.用模版寫了一個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 }
這是一個很簡單的程序，在收到請求后，把用戶名打印出來。
3.運行出現問題：The requested resource is not available.
4.查找咨詢，沒有解決。后來查看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>
因為這些都是自動生成，沒有想到過會出現問題。不過記起以前寫這個程序時<url-pattern>節點只是在<servlet-name>節點內容前多一個"/"，嘗試將其改為/loginserv，重啟服務運行頁面。一些正常。
總結：這應該是這種問題出現的其中一種解決途徑。