在JS中使用AJAX请求跨域时候，会提示错误
Failed to load http://localhost:8889/xxxxxxxxx: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8085' is therefore not allowed access.
这个是提示服务端没有设置 'Access-Control-Allow-Origin'，
以Spring mvc为例
设置Access-Control-Allow-Origin即可，如下：
@RequestMapping(value = "/test", method = RequestMethod.POST)
@ResponseBody
public String test(String param,HttpServletResponse response) {
response.setHeader("Access-Control-Allow-Origin", "*");
return "test";
}设置Header值，完成后重启服务，
即可正常访问！