Spring MVC过滤器-登录过滤的代码实现

/** 
 * 
 * @author geloin 
 * @date 2012-4-10 下午2:37:38 
 */ 
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; 
 
/** 
 * 登录过滤 
 * 
 * @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 { 
 
    // 不过滤的uri 
    String[] notFilter = new String[] { "login.html","index.html" }; 
 
    // 请求的uri 
    String uri = request.getRequestURI(); 
 
    // uri中包含background时才进行过滤 
    if (uri.indexOf("background") != -1) { 
      // 是否过滤 
      boolean doFilter = true; 
      for (String s : notFilter) { 
        if (uri.indexOf(s) != -1) { 
          // 如果uri中包含不过滤的uri，则不进行过滤 
          doFilter = false; 
          break; 
        } 
      } 
      if (doFilter) { 
        // 执行过滤 
        // 从session中获取登录者实体 
        Object obj = request.getSession().getAttribute("loginedUser"); 
        if (null == obj) { 
          // 如果session中不存在登录者实体，则弹出框提示重新登录 
          // 设置request和response的字符集，防止乱码 
          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('网页过期，请重新登录！');"); 
          builder.append("window.top.location.href='"); 
          builder.append(loginPage); 
          builder.append("';"); 
          builder.append("</script>"); 
          out.print(builder.toString()); 
        } else { 
          // 如果session中存在登录者实体，则继续 
          filterChain.doFilter(request,response); 
        } 
      } else { 
        // 如果不执行过滤，则继续 
        filterChain.doFilter(request,response); 
      } 
    } else { 
      // 如果uri中不包含background，则继续 
      filterChain.doFilter(request,response); 
    } 
  } 
 
} 

<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>