保存进度！

code/java/car_dealer/src/main/webapp/file_upload.html

@@ -67,6 +67,7 @@
 
             const xhr = new XMLHttpRequest();
 
+            //处理进度
             xhr.upload.onprogress = function (event) {
                 if (event.lengthComputable) {
                     let percent = Math.round(
@@ -77,6 +78,7 @@
                 }
             };
 
+            //传送完成
             xhr.onload = function (event) {
                 console.log(xhr.responseText);