Spring MVC過濾器-登錄過濾

以下代碼是繼承OncePerRequestFilter實現登錄過濾的代碼：

package com.test.spring.filter;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.filter.OncePerRequestFilter;
/**

登錄過濾

@author geloin
@date 2012-4-10 下午2:37:38
*/
public class SessionFilter extends OncePerRequestFilter {
/*

(non-Javadoc)

@see
org.springframework.web.filter.OncePerRequestFilter#doFilterInternal(
javax.servlet.http.HttpServletRequest,
javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)
*/
@Override
protected void doFilterInternal(HttpServletRequest request,

 HttpServletResponse response, FilterChain filterChain)
 throws ServletException, IOException {


// 不過濾的uri
 String[] notFilter = new String[] { "login.html", "index.html" };
// 請求的uri
 String uri = request.getRequestURI();
// uri中包含background時才進行過濾
 if (uri.indexOf("background") != -1) {

 // 是否過濾
 boolean doFilter = true;
 for (String s : notFilter) {
     if (uri.indexOf(s) != -1) {
         // 如果uri中包含不過濾的uri，則不進行過濾
         doFilter = false;
         break;
     }
 }
 if (doFilter) {
     // 執行過濾
     // 從session中獲取登錄者實體
     Object obj = request.getSession().getAttribute("loginedUser");
     if (null == obj) {
         // 如果session中不存在登錄者實體，則彈出框提示重新登錄
         // 設置request和response的字符集，防止亂碼
         request.setCharacterEncoding("UTF-8");
         response.setCharacterEncoding("UTF-8");
         PrintWriter out = response.getWriter();
         String loginPage = "....";
         StringBuilder builder = new StringBuilder();
         builder.append("<script type=\"text/javascript\">");
         builder.append("alert('網頁過期，請重新登錄！');");
         builder.append("window.top.location.href='");
         builder.append(loginPage);
         builder.append("';");
         builder.append("</script>");
         out.print(builder.toString());
     } else {
         // 如果session中存在登錄者實體，則繼續
         filterChain.doFilter(request, response);
     }
 } else {
     // 如果不執行過濾，則繼續
     filterChain.doFilter(request, response);
 }

} else {

 // 如果uri中不包含background，則繼續
 filterChain.doFilter(request, response);

}
}




}</pre> 


 寫完過濾器后，需要在web.xml中進行配置： 

<filter>
    <filter-name>sessionFilter</filter-name>
    <filter-class>com.test.spring.filter.SessionFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>sessionFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>