添加注释

src/main/webapp/resources/js/preview/app.js

@@ -10,9 +10,11 @@ $("#download_excel_with_only_data").click(function() {
 	downloadReport("xls_with_only_data");
 });
 
+// 从当前预览页面链接中获取参数
 var downloadReport = function(exportFileType) {
 	var downloadUrl = "print/export" + window.location.search;
 	exportFileType = exportFileType || "pdf";
+	// 导出文件的格式
 	downloadUrl += "&exportFileType=" + exportFileType;
 	console.log(downloadUrl);
 	window.location = downloadUrl;