Cocos Creator 封装的get， post 请求

export class HttpUtil{

 private static baseUrl:string = "https://xxx.xxx.xxx/xxxx/";

 public static get(url, params:object = {}, callback){
 let dataStr = ''; 
 Object.keys(params).forEach(key => {
 dataStr += key + '=' + encodeURIComponent(params[key]) + '&';
        })
 if (dataStr !== '') {
 dataStr = dataStr.substr(0, dataStr.lastIndexOf('&'));
 url = url + '?' + dataStr;
        }
 url = HttpUtil.baseUrl + url;
 let xhr = cc.loader.getXMLHttpRequest();
 xhr.open("GET", url, true);
 xhr.setRequestHeader("Content-Type","text/plain;charset=UTF-8");  
 xhr.onreadystatechange = function () {
 if (xhr.readyState === 4) {
 let response = xhr.responseText;
 if (xhr.status >= 200 && xhr.status < 300) {
 let httpStatus = xhr.statusText;
 callback(true, JSON.parse(response));
                }else{
 callback(false, response);
                }
            }
        };
 xhr.send();
    }

 //Post请求
 public static post(url, param:object = {}, callback){
 url = HttpUtil.baseUrl + url;
 var xhr = cc.loader.getXMLHttpRequest();  
 let dataStr = ''; 
 Object.keys(param).forEach(key => {
 dataStr += key + '=' + encodeURIComponent(param[key])+ '&';
        })
 if (dataStr !== '') {
 dataStr = dataStr.substr(0, dataStr.lastIndexOf('&'));
        }
 xhr.open("POST", url, true);
 xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded"
        );  
 xhr.onreadystatechange = function () {  
 if (xhr.readyState === 4) {
 let response = xhr.responseText;
 if (xhr.status >= 200 && xhr.status < 300) {
 let httpStatus = xhr.statusText;
 callback(true, JSON.parse(response));
                }else{
 callback(false, response);
                }
            }
        };
 xhr.send(dataStr);
    }
}