Spring MVC中处理ajax请求的跨域问题与注意事项详解

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;
//HandlerInterceptorAdapter//跨域设置
public class CrossInterceptor extends HandlerInterceptorAdapter {
　　
 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
 response.addHeader("Access-Control-Allow-Origin","http://localhost:8080");
 response.addHeader("Access-Control-Allow-Methods","*");
 response.addHeader("Access-Control-Max-Age","100");
 response.addHeader("Access-Control-Allow-Headers", "Content-Type");
 //允许客户端发送cookies true表示接收，false不接受 默认为false？
 response.addHeader("Access-Control-Allow-Credentials","true");
 return super.preHandle(request, response, handler);
 } 

}

$.ajax({
 url: url+'/checkout.action',
 type: 'GET',
 dataType: '',
 data: {verifyCode: VerificationCodeInput.value},
 //添加跨域
 async: false, 
 xhrFields: { 
  withCredentials: true 
 }, 
 crossDomain: true, 
 success:function(data){
  console.log(data);
 }
 });

　　　　 request.getRequestDispatcher(xxxx.html").forward(request, response);
　　　　response.sendRedirect(http://www.baidu.com);

String requestType = request.getHeader("X-Requested-With");
 if(requestType != null && "XMLHttpRequest".equalsIgnoreCase(requestType.trim())) {
  //如果是ajax请求就设置一个自定义响应头
  response.setHeader("sessionStatus", "timeout");　　　　　　　 //设置错误码以及错误码提示
  response.sendError(666, "session timeout");
  return false;
 }

$.ajaxSetup({
 type:'post',
 complete:function(xhr, ts){ //XMLHttpRequest, textStatus
 var sessionStatus = xhr.getResponseHeader('sessionstatus');
 if(sessionStatus == 'timeout') {
  alert('用户没有登陆，请登录！');
  window.top.location.href = 'Login.html';
 }
 }
});