ajax跨域请求

有时需要跨域请求接口，这时需要返回jsonp格式的数据，示例代码如下：

后端Java代码

　　 @RequestMapping("/jsonp")
    @ResponseBody
    public String loginjsonp(HttpServletRequest request,HttpServletResponse response,String params,String callback){
        String result = "{'code':'200','data':'001','msg':'操作成功','success':'true'}";

          result=callback+"("+result+")";
         
          return result;


    }

前端js代码

$.ajax({
                     
                      url: 'http://test.aaa.g.cn/user/jsonp.do',
                     
                      type: 'post',
                     
                      dataType:'jsonp',
                     
                      jsonp: "callback",
                     
                      data: {"params":'{"client_id":"6b896da1307f4dd08067faa8ec4843ad","username":"test06","password":"1191111","usertype":"0"}'},
                     
                      success:function(data){
                          
                          alert(data.code);
                          
                          alert(data.msg);
                     
                      },
                     
                      error:function(data){
                     
                        alert(data.code);
                          
                          alert(data.msg);
                     
                      }
                     
                    });