Spring MVC过滤器-登录过滤详解编程语言

以下代码是继承OncePerRequestFilter实现登录过滤的代码：

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); 
        } 
    } 
  
}

写完过滤器后，需要在web.xml中进行配置：

<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>