用户登录过滤例子代码,Java代码库,德仔网

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【Java】用户登录过滤例子
作者:Alex / 发布于2017/1/18/ 784
import   javax.servlet.Filter;  
  import   javax.servlet.FilterConfig;  
  import   javax.servlet.ServletException;  
  import   javax.servlet.ServletRequest;  
  import   javax.servlet.ServletResponse;  
  import   javax.servlet.FilterChain;  
  import   java.io.IOException;  
  import   javax.servlet.http.HttpServletRequest;  
  import   javax.servlet.http.HttpSession;  
  import   javax.servlet.http.HttpServletResponse;  
   
  public   class   RightFilter  
          implements   Filter   {  
      public   void   init(FilterConfig   filterConfig)   throws   ServletException   {  
      }  
   
      public   void   doFilter(ServletRequest   request,   ServletResponse   response,  
                                                FilterChain   chain)   throws   IOException,   ServletException   {  
          HttpServletRequest   req   =   (HttpServletRequest)   request;  
          HttpServletResponse   res   =   (HttpServletResponse)   response;  
           
          HttpSession   session   =   req.getSession(true);  
   
          //从session里取的用户名信息  
          String   username   =   (String)   session.getAttribute("username");  
           
          //判断如果没有取到用户信息,就跳转到登陆页面  
          if   (username   ==   null   ||   "".equals(username))   {  
              //跳转到登陆页面  
              res.sendRedirect("http://"+req.getHeader("Host")+"/login.jsp");  
          }  
          else   {  
              //已经登陆,继续此次请求  
              chain.doFilter(request,response);  
          }  
      }  
   
      public   void   destroy()   {  
      }  
  }  
   
   
  下面配置这个过滤器  
  然后在web.xml里配置那些JSP文件需要登陆权限验证:  
   
  1.如果是某个具体的JSP文件(如a.jsp)需要登陆验证  
  <web-app>  
      ...  
      <filter>  
          <filter-name>right</filter-name>  
          <filter-class>com.taihuatalk.taihua.common.common.RightFilter</filter-class>  
      </filter>  
   
      <filter-mapping>  
          <filter-name>right</filter-name>  
          <url-pattern>/a.jsp</url-pattern>  
      </filter-mapping>  
      ...  
  </web-app>  
   
  2.如果是某一个目录(如a/目录)整个目录下的文件都需要登陆验证:  
  <web-app>  
      ...  
      <filter>  
          <filter-name>right</filter-name>  
          <filter-class>com.taihuatalk.taihua.common.common.RightFilter</filter-class>  
      </filter>  
   
      <filter-mapping>  
          <filter-name>right</filter-name>  
          <url-pattern>/a/*</url-pattern>  
      </filter-mapping>  
      ...  
  </web-app>
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