Ajax请求成功，但一值不进success回调，却进error

Ajax请求成功，回调进入error，说明返回错误。

1、返回值类型错误：修改Ajax对应dataType即可。

2、如果是跨域请求；建议修改返回头:

response.setHeader("Content-Type", "text/html; charset=UTF-8"); response.setHeader("Access-Control-Allow-Origin", "http://220bb97a.nat123.cc");//设置ajax运行跨域访问 response.setHeader("Access-Control-Allow-Credentials","true"); response.setHeader("Access-Control-Allow-Origin","*");//允许所有来源访问 response.setHeader("Access-Control-Allow-Methods","*"); response.setHeader("Access-Control-Allow-Headers","Origin, X-Requested-With, Content-Type, Accept"); response.getWriter().print(json);