如何重定向到另一页的时候就已经验证的用户访问登陆页面 [英] How to redirect to another page when already authenticated user accesses login page

问题描述

我想知道是否有可能将用户重定向如果某 C：？如果 clausule是真正

  c为C：如果测试=＃{} loginController.authenticated＆GT;
 //重定向到索引页
＆LT; / C：如果＆GT;
 

解决方案

是的，它是可能的。

不过，我建议你为/login.jsp和正向过滤到其他网页应用过滤器，如果用户已经登录。

下面是告诉你如何做到这一点使用过滤器的例子：

 公共类LoginPageFilter实现过滤器
{
   公共无效的init（一个FilterConfig一个FilterConfig）抛出ServletException异常
   {   }   公共无效的doFilter（ServletRequest中的servletRequest，ServletResponse的ServletResponse的，FilterChain filterChain）抛出IOException异常，ServletException异常
   {
       HttpServletRequest的请求=（HttpServletRequest的）的servletRequest;
       HttpServletResponse的响应=（HttpServletResponse的）ServletResponse的;       如果（request.getUserPrincipal（）！= NULL）{//如果用户已通过身份验证
           response.sendRedirect（/ index.jsp的）; //或者使用转发的RequestDispatcher
       }其他{
           filterChain.doFilter（的servletRequest，ServletResponse的）;
       }
   }   公共无效的destroy（）
   {   }
}
 

在web.xml中添加此过滤器enty

 ＆LT;滤光器＆gt;
    ＆LT;过滤器名称＆gt;＆LoginPageFilter LT; /过滤器名称＆gt;
    ＆LT;滤波级＆GT;
        com.sample.LoginPageFilter
    ＆LT; /过滤器类＆GT;
    ＆LT;初始化参数＆GT;
       ＆LT;参数-名称＆gt;测试参数＆LT; /参数 - 名称＆gt;
       ＆LT;参数值＆gt;这参数用于测试和LT; /参数值＆GT;
    ＆LT; /初始化参数＆GT;
＆LT; /滤光器＆gt;＆LT;过滤器映射＆GT;
    ＆LT;过滤器名称＆gt;＆LoginPageFilter LT; /过滤器名称＆gt;
    ＆LT; URL模式＆GT; /login.jsp< / URL模式＆GT;
＆LT; /过滤器映射＆GT;
 

I was wondering if it was possible to redirect users if a certain c:if clausule is true?

<c:if test="#{loginController.authenticated}">
 //redirect to index page
</c:if>

解决方案

Yes it is possible.

But, I would suggest you to apply filter for /login.jsp and in the filter forward to the other page if the user has already logged in.

Here is the example which tells how to do this using filter:

public class LoginPageFilter implements Filter
{
   public void init(FilterConfig filterConfig) throws ServletException
   {

   }

   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,   FilterChain filterChain) throws IOException, ServletException
   {
       HttpServletRequest request = (HttpServletRequest) servletRequest;
       HttpServletResponse response = (HttpServletResponse) servletResponse;

       if(request.getUserPrincipal() != null){ //If user is already authenticated
           response.sendRedirect("/index.jsp");// or, forward using RequestDispatcher
       } else{
           filterChain.doFilter(servletRequest, servletResponse);
       }
   }

   public void destroy()
   {

   }
}

Add this filter enty in the web.xml

<filter>
    <filter-name>LoginPageFilter</filter-name>
    <filter-class>
        com.sample.LoginPageFilter
    </filter-class>
    <init-param>
       <param-name>test-param</param-name>
       <param-value>This parameter is for testing.</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>LoginPageFilter</filter-name>
    <url-pattern>/login.jsp</url-pattern>
</filter-mapping>

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