web程序的统一认证实现：filter操作

1   package  filter;  
2    
3   import  java.io.IOException;  
4   import  javax.servlet.Filter;  
5   import  javax.servlet.FilterChain;  
6   import  javax.servlet.FilterConfig;  
7   import  javax.servlet.ServletContext; 
8   import  javax.servlet.ServletException; 
9   import  javax.servlet.ServletRequest;
10   import  javax.servlet.ServletResponse; 
11   import  javax.servlet.http.HttpServletRequest; 
12   import  javax.servlet.http.HttpServletResponse; 
13   import  javax.servlet.http.HttpSession; 
14   
15   
16   public   class  SessionCheck  implements  Filter {
17      
18       private  ServletContext context;
19       private  String targetUri; 
20  
21       public   void  destroy() { 
22           //  TODO Auto-generated method stub 
23           
24      } 
25   
26       public   void  doFilter( 
27              ServletRequest request,  
28              ServletResponse response, 
29              FilterChain chain)  throws  IOException, ServletException { 
30           //  TODO Auto-generated method stub 
31          HttpServletRequest httpRequest  =  (HttpServletRequest)request; 
32          HttpServletResponse httpResponse  =  (HttpServletResponse) response; 
33           /**  
34          * getSession(false)此方法如果得不到session，也不会自动创建一个session 
35          *  
36          * 插曲：看到getSeesion(false)表示之前没看到过，不知道意思，本能的猜测是： 
37          * 如果没有得到sesson，则返回null，如果参数为true，得不到session那就重新创建一个 
38          * 因为只是猜测，所以上csdn查了下，结果看到一帖子，说的果断和我的理解相反，
              接着看，下面各种各样的回复，琳琅满目 
39          * 当然，在找之前已经用debug验证过了，我的想法只要不是验证方法错了那我的理解肯定是对的 
40          * 结果在csdn看到几乎一样的问题，而且一楼回答刚好跟我的完全相反，并且楼主还给了30分，这让我不由的蛋疼了下，
41          * 结论完全相反呀，继续忐忑的往下看，一哥们什么都没解释，直接把关于session的官方文档给拉出来贴着，全英文，还好哥虽然没过6鸡
42          * 但也还是能看懂几个abc的，意思跟我理解一样，忐忑的心终于有点放下了，继续往下看，一看id，俨然是楼主本人，一看内容，我热泪盈眶 
43          * 楼主你Y真是好人啊，一楼理解完全相反你Y居然给30分，你妹啊，害得我还犹豫了半天，纳闷了半天，不过还好你出来纠正了你之前的 
44          * NC行径，也算是一大进步。 
45  */  
46          HttpSession session  =  httpRequest.getSession( false );
47           
48           if (session  !=   null ){
49              String passed  =  (String)session.getAttribute( " passed " ); 
50               if ( " true " .equals(passed)){ 
51                  chain.doFilter(httpRequest, httpResponse);
52                   /**  
53                  * return 说明filter在执行了chain.doFilter之后会返回来继续执行原先的filter
54                  * 相当于一个递归调用 
55                  * return 下面的代码表示执行失败的情况 
56  */
57                   return ; 
58              } else   if ( " passing " .equals(passed)){ 
59                   /**  
60                  * httpRequest.getRequestURL()获取绝对路径
61                  * 例如http://127.0.0.1:8088/webTest/filter1/login.jsp 
62                  *  
63                  * httpRequest.getRequestURI()获取相对路径。 
64                  * /webTest/filter/LoginCheck,其中filter/LoginCheck为jsp页面中form表单的action值
65                  * 对应的Servlet的<url-pattern>要写成/filter/LoginCheck 66  */
67                   if ( " /webTest/filter/LoginCheck " .equals( new  String(httpRequest.getRequestURI()))){ 
68                      chain.doFilter(httpRequest, httpResponse); 
69                       return ; 
70                  }
71              } 
72               /**  
73              * 如果之前的filter执行均失败，则说明这个session中的passed认证已经是错误的，必须删除 
74  */  
75              session.removeAttribute( " passed " ); 
76          } 
77           /**  
78          * requestUrl保存当前请求的url 
79          * query保存当前请求下的参数 
80  */
81          StringBuffer requestUrl  =   new  StringBuffer(httpRequest.getRequestURI());
82          String query  =  httpRequest.getQueryString(); 
83           if ( null   !=  query){ 
84              requestUrl.append(query); 
85          }
86           /**
87          * 设置request范围内的originalUri（认证之前的请求地址），用于在login页面获取，并可以通过隐藏参数的形式把这个值传递到LoginCheck 
88          * 当登录之后就可以直接转到login认证之前的页面 
89  */  
90          httpRequest.setAttribute( " originalUri " ,  new  String(requestUrl));
91          httpRequest.getRequestDispatcher(targetUri).forward(httpRequest, httpResponse); 
92      } 
93   
94       public   void  init(FilterConfig config)  throws  ServletException { 
95           //  TODO Auto-generated method stub 
96           this .context  =  config.getServletContext(); 
97           /**  
98          * 获取filter的初始化参数，当需要认证的时候都会跳转到targetUri指定页面，一般都是登录页面
99  */
100           this .targetUri  =  config.getInitParameter( " targetUri " );
101      }
102  
103  
104  }

1   package  filter; 
2   
3   import  java.io.IOException;
4   import  javax.servlet.ServletException;
5   import  javax.servlet.http.HttpServlet;
6   import  javax.servlet.http.HttpServletRequest;
7   import  javax.servlet.http.HttpServletResponse;
8   import  javax.servlet.http.HttpSession; 
9  
10   public   class  LoginCheck  extends  HttpServlet {
11      
12       private   static   final   long  serialVersionUID  =   - 4075113258177758412L ;
13     
14       protected   void  doPost(HttpServletRequest request,HttpServletResponse response)
15           throws  IOException,ServletException{
16          String user  =  request.getParameter( " user " );
17          String pwd  =  request.getParameter( " pwd " );
18          String targetUri  =  request.getParameter( " originalUri " );
19          
20           if ( ! " LH123 " .equals(user)  ||   ! " 123LH " .equals(pwd)){
21              System.out.println( " 认证失败 " );
22               throw   new  ServletException( " 认证失败 " );
23          }
24           /**
25          * 认证成功的情况
26  */
27          HttpSession session  =  request.getSession();
28          session.setAttribute( " passed " ,  " true " );
29          request.setAttribute( " user " , user);
30          request.setAttribute( " pwd " , pwd);
31           if ( ! "" .equals(targetUri)){
32               /**
33              * SessionCheck中保存入的之前的请求的uri的格式为：/webTest/filter/filter3.jsp
34              * 而getRequestDispatcher这种方法传递过去的是一个相对路径，不需要再加上/webTest
35              * 这个方法可以把页面表单的值传递到另外一个页面，而不只是纯粹的跳转
36  */
37              request.getRequestDispatcher(targetUri.substring( 8 )).forward(request, response);
38          } else {
39              response.sendRedirect( " http://127.0.0.1:8088/webTest/filter1/filter2.jsp " );
40          }
41      }
42  }

<% @ page language = " java "  import = " java.util.* "  pageEncoding = " UTF-8 " %>
<% @ taglib prefix  = " c "  uri = " http://java.sun.com/jsp/jstl/core " %>
<%
String  path  =  request.getContextPath();
String  basePath  =  request.getScheme() + " :// " + request.getServerName() + " : " + request.getServerPort() + path + " / " ;
%>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" >
< html >   
   < head >
     < base  href ="<%=basePath%>" >
         < title > 测试filter </ title >
         < meta  http-equiv ="pragma"  content ="no-cache" >
         < meta  http-equiv ="cache-control"  content ="no-cache" >
         < meta  http-equiv ="expires"  content ="0" >
         < meta  http-equiv ="keywords"  content ="keyword1,keyword2,keyword3" >     
         < meta  http-equiv ="description"  content ="This is my page" >
         <!--     <link rel="stylesheet" type="text/css" href="styles.css">     -->   
    </ head >  
   
< body >     
    < c:set  var  = "passed"  value  = "passing"  scope  = "session" >
    </ c:set >
     < form  action  = "filter/LoginCheck"  method  = "post" >
         < table >
             < tr >
                 < th > 用户账号： </ th >
                 < td >< input  type  = "text"  name  = "user"  value  = "" /></ td >
             </ tr >
             < tr >
                 < th > 登录密码： </ th >
                 < td >< input  type  = "password"  name  = "pwd"  value  = "" /></ td >
             </ tr >
                 < th >
                     < input  type  = "hidden"  name  = "originalUri"  value  = "${requestScope.originalUri}" />
                 </ th >
             < tr >
                < td >< input  type  = "submit"  name  = "submit"  value  = "提交" /></ td >             </ tr >
         </ table >
     </ form >
   </ body >
</ html >

1  <% @ page language = " java "  import = " java.util.* "  pageEncoding = " UTF-8 " %>  
2  <% @ taglib prefix  = " c "  uri  = " http://java.sun.com/jsp/jstl/core " %>  
3  <%  
4   String  path  =  request.getContextPath(); 
5   String  basePath  =  request.getScheme() + " :// " + request.getServerName() + " : " + request.getServerPort() + path + " / " ; 
6   %>  
7  
8  <! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" >  
9  < html >
10    < head >
11      < base  href ="<%=basePath%>" >
12     
13      < title > My JSP 'filter2.jsp' starting page </ title >
14     
15      < meta  http-equiv ="pragma"  content ="no-cache" >
16      < meta  http-equiv ="cache-control"  content ="no-cache" >
17      < meta  http-equiv ="expires"  content ="0" >    
18      < meta  http-equiv ="keywords"  content ="keyword1,keyword2,keyword3" >
19      < meta  http-equiv ="description"  content ="This is my page" >
20      <!-- 21     <link rel="stylesheet" type="text/css" href="styles.css">22  --> 23 24    </ head > 25   26    < body >
27       HHHHH
28      
29    </ body >
30  </ html >

1  <% @ page language = " java "  import = " java.util.* "  pageEncoding = " UTF-8 " %>

2  <% @ taglib prefix = " c "  uri = " http://java.sun.com/jsp/jstl/core " %>

3  <%

4   String  path  =  request.getContextPath();

5   String  basePath  =  request.getScheme() + " :// " + request.getServerName() + " : " + request.getServerPort() + path + " / " ;

6   % >

7  

8  <! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" >

9  < html >

10    < head >

11      < base  href ="<%=basePath%>" >

12    

13      < title > My JSP 'filter3.jsp' starting page </ title >

14    

15      < meta  http-equiv ="pragma"  content ="no-cache" >

16      < meta  http-equiv ="cache-control"  content ="no-cache" >

17      < meta  http-equiv ="expires"  content ="0" >     

18      < meta  http-equiv ="keywords"  content ="keyword1,keyword2,keyword3" >

19      < meta  http-equiv ="description"  content ="This is my page" >

20      <!-- 21     <link rel="stylesheet" type="text/css" href="styles.css">

22  -->

23

24    </ head >

25  

26    < body >

27      < c:out  value ="${user}" ></ c:out >   < br >

28      < c:out  value ="${pwd}" ></ c:out >   < br >

29    </ body >

30  </ html >

1  <? xml version="1.0" encoding="UTF-8" ?>

2  < web-app  version ="2.5"   

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  

6     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" >

7      < servlet >

8          < servlet-name > LoginCheck </ servlet-name >

9          < servlet-class > filter.LoginCheck </ servlet-class >

10      </ servlet >

11      < servlet-mapping >

12          < servlet-name > LoginCheck </ servlet-name >

13          < url-pattern > /filter/LoginCheck </ url-pattern >

14      </ servlet-mapping >

15    

16      < filter >

17          < filter-name > SessionCheck </ filter-name >

18          < filter-class > filter.SessionCheck </ filter-class >

19          < init-param >

20              < param-name > targetUri </ param-name >

21              < param-value > /filter1/login.jsp </ param-value >

22          </ init-param >

23      </ filter >

24      < filter-mapping >

25          < filter-name > SessionCheck </ filter-name >

26          < url-pattern > /* </ url-pattern >

27      </ filter-mapping >

28    < welcome-file-list >

29      < welcome-file > index.jsp </ welcome-file >

30    </ welcome-file-list >

31  </ web-app >