XMLHttpRequestエクスポートファイル

var request = new XMLHttpRequest();
	request.open("POST", BASE_URL + "?method=exportAsTxt");
	request.responseType = "blob"; //     blob
	request.onload = function() {
		if (this.status === 200) {
			var name = request.getResponseHeader("Content-disposition");
			var filename = name.substring(20, name.length);
			var blob = this.response;
			var reader = new FileReader();
			reader.readAsDataURL(blob);
			reader.onload = function(e) {
				var a = document.createElement('a');
				a.download = filename;
				a.href = e.target.result;
				$("body").append(a);
				a.click();
				$(a).remove();
			}
		}
	}
	request.send();

        HttpServletResponse response = ServletActionContext.getResponse();
        response.setContentType("application/octet-stream;charset=UTF-8");
        response.setHeader("Content-Disposition", "attachment;filename=" + METER_MONTHLY_READING_REPORT + month + ".txt");
        exportAsTxt(response.getOutputStream(), datas);