使用filter過濾器實現登陸權限驗證

1.首先寫一個權限過濾filter類,實現Filter接口

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);

    //從session裏取的用戶名信息
    String username = (String) session.getAttribute("username");
    
    //判斷如果沒有取到用戶信息,就跳轉到登陸頁面
    if (username == null || "".equals(username)) ...{
      //跳轉到登陸頁面
      res.sendRedirect("http://"+req.getHeader("Host")+"/login.jsp");
    }
    else ...{
      //已經登陸,繼續此次請求
      chain.doFilter(request,response);
    }
  }

  public void destroy() ...{
  }
} 

 

2.然後在web.xml裏配置需要登陸權限驗證的JSP文件:

     a.如果是某個具體的JSP文件(如a.jsp)需要登陸驗證

<web-app>
  ...
  <filter>
    <filter-name>right</filter-name>
    <filter-class>com.taihuatalk.taihua.common.RightFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>right</filter-name>
    <url-pattern>/a.jsp</url-pattern>
  </filter-mapping>
  ...
</web-app>

    b.如果是某一個目錄(如a/目錄)整個目錄下的文件都需要登陸驗證:

<web-app>
  ...
  <filter>
    <filter-name>right</filter-name>
    <filter-class>com.taihuatalk.taihua.common.RightFilter</filter-class>
  </filter>

  <filter-mapping>
    <filter-name>right</filter-name>
    <url-pattern>/a/*</url-pattern>
  </filter-mapping>
  ...
</web-app>