$.ajax({
	method:'post',
	url:'http://127.0.0.1:8080/test/user/login',
	data:{loginName:$("#loginName").val(),password:$("#password").val()},
	dataType:'json',
	success:function(data){
		var da = data;
		$.messager.alert('登陆提示',data.msg+"---"+data.success,'info');
	},
	error:function(data){
		var da = data;
		$.messager.alert('失败提示',data.msg+"---"+data.success,'info');
	}
});

如题 上面的方法有问题吗？为什么一直都是执行到error里面去呢？后台debug时action返回的确实是json字符串!!!!

后台返回的json字符串：{"success":false,"msg":"登陆名不存在或者密码错误！"}用的springMVC 

返回字符串的代码：

public static void returnJsonString(HttpServletResponse response,Object object){
     try {
         esponse.setContentType("application/json");
         String jsonStr = JSON.toJSONString(object);
         System.out.println(jsonStr);
         writer(response,jsonStr);
     } catch (JSONException e) {
         e.printStackTrace();
         logger.error("转换json格式字符串失败！"+e.getMessage());
     }
 }

writer 方法如下：

private static void writer(HttpServletResponse response,String str){
     try { 
         PrintWriter out= null;
         out = response.getWriter();
         out.print(str);
         out.flush();
         out.close();
     } catch (IOException e) {
         e.printStackTrace();
     }
 }