問題：使用window.location.href來跳轉頁面的時候，后端只需實現一個過濾器就可以在session超時的情況下重定向到登陸頁面。但是使用ajax呢？使用ajax來執行會發生302錯誤，并且頁面不可能跳轉。下面就針對這個問題來貼上我的前后端代碼。

1、session過濾器

import java.io.IOException;<p style="text-align: center"><img alt=""import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;<p style="text-align: center"><img alt=""public class SessionFilter implements Filter {<p style="text-align: center"><img alt="" public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterChain)   throws IOException, ServletException {  HttpServletRequest request = (HttpServletRequest) req;  HttpServletResponse response = (HttpServletResponse) res;<p style="text-align: center"><img alt=""  String requestUri = request.getRequestURI();<p style="text-align: center"><img alt=""  if (requestUri.indexOf("/login.html") > 0 || requestUri.indexOf("/system/login") > 0) {   return ;  }<p style="text-align: center"><img alt=""  HttpSession session = request.getSession(false);<p style="text-align: center"><img alt=""  if (session == null) {   // 如果是session超時，在此處做處理。   response.sendRedirect(request.getContextPath() + "/login.html");   return ;  }  try {   filterChain.doFilter(request, response);  } catch (Exception e) {   e.printStackTrace();  }  return ; }}

2、web.xml添加配置：

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

*3、重寫ajax

注意：此段代碼放在index頁

jQuery(function($){   var _ajax=$.ajax;   $.ajax=function(opt){    var _success = opt && opt.success || function(a, b){};    var _opt = $.extend(opt, {     success:function(data, textStatus){      _success(data, textStatus);      },     error:function(XMLHttpRequest, textStatus, errorThrown){      //alert(XMLHttpRequest.responseText);      //如果請求發生錯誤，會返回登陸頁面源代碼，如果源代碼里面存在lovnx這個字符串，前端就重定向到登陸頁面      var reData = XMLHttpRequest.responseText + "";      if(reData.indexOf('lovnx') != -1) {       window.location.href="/manager/login.html" rel="external nofollow" ;       return;      }     }    });    return _ajax(_opt);   };  });