/**XML请求工具 */
export default class XMLHttp{
    /**XML 请求 */
   static Request(url:string,Back:Function,ErrorBack?:Function){
        let xhr: XMLHttpRequest = new XMLHttpRequest();
        xhr.open('GET', url, true);
        xhr.onreadystatechange = () => {
            if (xhr.readyState === 4 && (xhr.status >= 200 && xhr.status < 300)) {
                if (xhr.responseText.length > 0) {
                    Back(xhr.responseText)
                } else {
                    Back(null)
                }
            }
        }
        xhr.onerror = () => {
            Back(null)
        }
        xhr.send();
    }
}