区分网络请求时http和ajax请求

1. if (request.getHeader("x-requested-with") != null  

2.     && request.getHeader("x-requested-with").equalsIgnoreCase("XMLHttpRequest")) {  

3.     out.print("该请求是 AJAX 异步HTTP请求。");  

4. }else{   

5.     out.print("该请求是传统的 同步HTTP请求。");