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new 897280dfb8 WW-3526 docs: describe how to track file upload progress
(#359)
897280dfb8 is described below
commit 897280dfb8772c4a02886040b799fc763d43d62d
Author: Lukasz Lenart <[email protected]>
AuthorDate: Fri Oct 16 10:02:44 2026 +0200
WW-3526 docs: describe how to track file upload progress (#359)
Co-authored-by: Claude Opus 5.5 <[email protected]>
---
source/core-developers/action-file-upload.md | 51 ++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/source/core-developers/action-file-upload.md
b/source/core-developers/action-file-upload.md
index f19f958aa5..b2a704d94b 100644
--- a/source/core-developers/action-file-upload.md
+++ b/source/core-developers/action-file-upload.md
@@ -377,6 +377,57 @@ you can simple set
in struts.xml to start using it.
+### Upload Progress
+
+Struts does not track upload progress itself. To show a progress bar, use the
browser's `XMLHttpRequest.upload`
+progress events, which report the bytes sent so far without any server-side
support:
+
+```js
+const xhr = new XMLHttpRequest();
+xhr.upload.onprogress = (e) => {
+ if (e.lengthComputable) {
+ progressBar.value = e.loaded / e.total;
+ }
+};
+xhr.open('POST', form.action);
+xhr.send(new FormData(form));
+```
+
+If you need progress on the server side, extend one of the parsers and
register a Commons FileUpload
+`ProgressListener`:
+
+```java
+public class ProgressTrackingMultiPartRequest extends JakartaMultiPartRequest {
+
+ private HttpServletRequest request;
+
+ @Override
+ public void parse(HttpServletRequest request, String saveDir) throws
IOException {
+ this.request = request;
+ super.parse(request, saveDir);
+ }
+
+ @Override
+ protected JakartaServletDiskFileUpload prepareServletFileUpload(Charset
charset, Path saveDir) {
+ JakartaServletDiskFileUpload upload =
super.prepareServletFileUpload(charset, saveDir);
+ upload.setProgressListener((bytesRead, contentLength, items) -> {
+ // publish bytesRead / contentLength where your application can
read it
+ });
+ return upload;
+ }
+}
+```
+
+and register it as the parser in `struts.xml`:
+
+```xml
+<bean type="org.apache.struts2.dispatcher.multipart.MultiPartRequest"
name="progress"
+ class="com.example.ProgressTrackingMultiPartRequest" scope="prototype"/>
+<constant name="struts.multipart.parser" value="progress"/>
+```
+
+The same approach works with `JakartaStreamMultiPartRequest`.
+
### Request validation
The `struts.multipart.validationRegex` is used to define a RegEx to be used to
validate if the incoming request is a
