feat: Add overloaded fromInputStream method with fileNameOverride (#24044)

Fixes #22278

---------

Co-authored-by: Tomi Virtanen <tltv@vaadin.com>

Author: TatuLund

flow-server/src/main/java/com/vaadin/flow/server/streams/DownloadHandler.java

@@ -370,6 +370,32 @@ static InputStreamDownloadHandler fromInputStream(
         return new InputStreamDownloadHandler(callback);
     }
 
+    /**
+     * Generate a function for downloading from a generated InputStream.
+     * <p>
+     * <code>DownloadResponse</code> instances can be created using various
+     * factory methods or with new operator.
+     * <p>
+     * File name override is appended to the download url as the logical name of
+     * the target file.
+     * <p>
+     * The {@link DownloadEvent#getFileName()} of the
+     * {@link InputStreamDownloadCallback} returns the given
+     * {@code fileNameOverride}.
+     *
+     * @param callback
+     *            a function that will be called on download
+     * @param fileNameOverride
+     *            download file name that overrides the name taken from
+     *            <code>path</code> and also used as a download request URL
+     *            postfix
+     * @return DownloadHandler implementation for download from an input stream
+     */
+    static InputStreamDownloadHandler fromInputStream(
+            InputStreamDownloadCallback callback, String fileNameOverride) {
+        return new InputStreamDownloadHandler(callback, fileNameOverride);
+    }
+
     /**
      * Generate a function for downloading from a generated InputStream with the
      * given progress listener.
@@ -391,4 +417,37 @@ static InputStreamDownloadHandler fromInputStream(
         downloadHandler.addTransferProgressListener(listener);
         return downloadHandler;
     }
+
+    /**
+     * Generate a function for downloading from a generated InputStream with the
+     * given progress listener.
+     * <p>
+     * <code>DownloadResponse</code> instances can be created using various
+     * factory methods or with new operator.
+     * <p>
+     * File name override is appended to the download url as the logical name of
+     * the target file.
+     * <p>
+     * The {@link DownloadEvent#getFileName()} of the
+     * {@link InputStreamDownloadCallback} returns the given
+     * {@code fileNameOverride}.
+     *
+     * @param callback
+     *            a function that will be called on download
+     * @param fileNameOverride
+     *            download file name that overrides the name taken from
+     *            <code>path</code> and also used as a download request URL
+     *            postfix
+     * @param listener
+     *            listener for transfer progress events
+     * @return DownloadHandler implementation for download from an input stream
+     */
+    static InputStreamDownloadHandler fromInputStream(
+            InputStreamDownloadCallback callback, String fileNameOverride,
+            TransferProgressListener listener) {
+        InputStreamDownloadHandler downloadHandler = new InputStreamDownloadHandler(
+                callback, fileNameOverride);
+        downloadHandler.addTransferProgressListener(listener);
+        return downloadHandler;
+    }
 }

flow-server/src/main/java/com/vaadin/flow/server/streams/InputStreamDownloadHandler.java

@@ -33,6 +33,7 @@ public class InputStreamDownloadHandler
         extends AbstractDownloadHandler<InputStreamDownloadHandler> {
 
     private final InputStreamDownloadCallback callback;
+    private String fileNameOverride;
 
     /**
      * Create an input stream download handler for given event -> response
@@ -45,13 +46,39 @@ public InputStreamDownloadHandler(InputStreamDownloadCallback callback) {
         this.callback = callback;
     }
 
+    /**
+     * Create an input stream download handler for given event -> response
+     * function.
+     * <p>
+     * The downloaded file fileNameOverride and download URL postfix will be set
+     * to <code>fileNameOverride</code>.
+     *
+     * @param callback
+     *            serializable function for handling download
+     * @param fileNameOverride
+     *            used as a downloaded file name as a download request URL
+     *            postfix, e.g.
+     *            <code>/VAADIN/dynamic/resource/0/5298ee8b-9686-4a5a-ae1d-b38c62767d6a/my-file.txt</code>
+     */
+    public InputStreamDownloadHandler(InputStreamDownloadCallback callback,
+            String fileNameOverride) {
+        this.callback = callback;
+        this.fileNameOverride = fileNameOverride;
+    }
+
     @Override
     public void handleDownloadRequest(DownloadEvent downloadEvent)
             throws IOException {
         VaadinResponse response = downloadEvent.getResponse();
         setTransferUI(downloadEvent.getUI());
         DownloadResponse download;
         try {
+            String resourceName = getUrlPostfix();
+            if (isInline()) {
+                downloadEvent.inline(resourceName);
+            } else {
+                downloadEvent.setFileName(resourceName);
+            }
             download = callback.complete(downloadEvent);
         } catch (IOException | RuntimeException e) {
             // Set status before output is closed (see #8740)
@@ -109,4 +136,9 @@ public void handleDownloadRequest(DownloadEvent downloadEvent)
             throw ioe;
         }
     }
+
+    @Override
+    public String getUrlPostfix() {
+        return fileNameOverride;
+    }
 }

flow-server/src/test/java/com/vaadin/flow/server/streams/InputStreamDownloadHandlerTest.java

@@ -139,6 +139,50 @@ public void onError(TransferContext context, IOException reason) {
         Mockito.verify(response).setContentType("application/octet-stream");
     }
 
+    @Test
+    void transferProgressListener_withFileNameOverride_listenersInvoked()
+            throws URISyntaxException, IOException {
+        List<String> invocations = new ArrayList<>();
+        DownloadHandler handler = DownloadHandler.fromInputStream(request -> {
+            byte[] data = getBytes();
+            ByteArrayInputStream inputStream = new ByteArrayInputStream(data);
+            return new DownloadResponse(inputStream, request.getFileName(),
+                    "application/octet-stream", data.length);
+        }, "downloadOverride", new TransferProgressListener() {
+            @Override
+            public void onStart(TransferContext context) {
+                assertEquals("downloadOverride", context.fileName());
+                invocations.add("onStart");
+            }
+
+            @Override
+            public void onProgress(TransferContext context,
+                    long transferredBytes, long totalBytes) {
+                assertEquals("downloadOverride", context.fileName());
+                invocations.add("onProgress");
+            }
+
+            @Override
+            public void onComplete(TransferContext context,
+                    long transferredBytes) {
+                assertEquals("downloadOverride", context.fileName());
+                invocations.add("onComplete");
+            }
+
+            @Override
+            public void onError(TransferContext context, IOException reason) {
+                invocations.add("onError");
+            }
+        });
+
+        handler.handleDownloadRequest(downloadEvent);
+
+        assertEquals(
+                List.of("onStart", "onProgress", "onProgress", "onComplete"),
+                invocations);
+        Mockito.verify(response).setContentType("application/octet-stream");
+    }
+
     @Test
     void transferProgressListener_addListener_errorOccurred_errorListenerInvoked()
             throws IOException {
@@ -445,6 +489,32 @@ void handleSetToInline_contentDispositionIsInlineWithFilename()
                 "inline; filename=\"download\"");
     }
 
+    @Test
+    void handleSetToInline_contentDispositionIsInlineWithFilenameOverride()
+            throws IOException {
+        InputStream stream = Mockito.mock(InputStream.class);
+        Mockito.when(
+                stream.read(Mockito.any(), Mockito.anyInt(), Mockito.anyInt()))
+                .thenReturn(-1);
+        DownloadHandler handler = DownloadHandler
+                .fromInputStream(event -> new DownloadResponse(stream,
+                        "download", "application/octet-stream", 0),
+                        "download_file")
+                .inline();
+
+        DownloadEvent event = new DownloadEvent(request, response, session,
+                new Element("t"));
+        Mockito.when(response.getOutputStream()).thenReturn(outputStream);
+        Mockito.when(response.getService()).thenReturn(service);
+        Mockito.when(service.getMimeType(Mockito.anyString()))
+                .thenReturn("application/octet-stream");
+
+        handler.handleDownloadRequest(event);
+
+        Mockito.verify(response).setHeader("Content-Disposition",
+                "inline; filename=\"download_file\"");
+    }
+
     @Test
     void contentLengthProvided_contentLengthHeaderSet() throws IOException {
         long expectedContentLength = 12345L;