Error handling issues with multiple file uploads in Wicket: FileNotFoundException

Question

Error handling issues with multiple file uploads in Wicket: FileNotFoundException

We are encountering a unique issue in our Wicket 6+ application related to the FileUpload.writeTo(file) method. This error only occurs with specific file types (docx, xlsx, java) within one particular form. Interestingly, the identical code functions correctly for attaching files in other locations. Any assistance or insights would be greatly appreciated. Thank you.

HTML:

<div wicket:id="filesInput"/>

Java:

add(new org.apache.wicket.markup.html.form.upload.MultiFileUploadField("filesInput", 
                    new PropertyModel<Collection<FileUpload>>(this, "uploads"), 5));

The error occurs specifically on the line fileUpload.writeTo(file); when invoked from the form's onSubmit method.

private void writeToFile(FileUpload fileUpload, Attachment attachment) {
    if (fileUpload == null) {
        return;
    }
    File file = AttachmentUtils.getFile(attachment, jtracHome);
    try {
        fileUpload.writeTo(file);
    }
    catch (Exception e) {
        throw new RuntimeException(e);
    }
}

Error Log:

[Insert log information here]

java ajax file-upload wicket

Answer 1

Answer №1

Here's where the issue arises in the code:

if (!outputFile.renameTo(file))
        {
            BufferedInputStream reader = null;
            BufferedOutputStream writer = null;
            try
            {
                reader = new BufferedInputStream(new FileInputStream(outputFile));
                writer = new BufferedOutputStream(new FileOutputStream(file));
                Streams.copy(reader, writer);
            }
            finally
            {
                IOUtils.closeQuietly(reader);
                IOUtils.closeQuietly(writer);
            }
        }

javadoc:

This method will only work for the first time it is invoked for a specific item. This is because if the method renames a temporary file, that file will no longer be available for copying or renaming later.

The error is occurring when attempting to open the "outputFile" File - indicating that it may no longer exist. It's possible that renameTo successfully did something with the file, but still returned false. Try setting a breakpoint there to investigate further. Could it be that the method is being called twice?

Regarding renameTo's javadoc:

Various aspects of this method's behavior depend on the platform: The rename operation may not be able to move a file across filesystems, may not be atomic, and may fail if a file with the destination path already exists. Always check the return value to ensure the rename operation was successful.

Answer 2

Here's where the issue arises in the code:

if (!outputFile.renameTo(file))
        {
            BufferedInputStream reader = null;
            BufferedOutputStream writer = null;
            try
            {
                reader = new BufferedInputStream(new FileInputStream(outputFile));
                writer = new BufferedOutputStream(new FileOutputStream(file));
                Streams.copy(reader, writer);
            }
            finally
            {
                IOUtils.closeQuietly(reader);
                IOUtils.closeQuietly(writer);
            }
        }

javadoc:

This method will only work for the first time it is invoked for a specific item. This is because if the method renames a temporary file, that file will no longer be available for copying or renaming later.

The error is occurring when attempting to open the "outputFile" File - indicating that it may no longer exist. It's possible that renameTo successfully did something with the file, but still returned false. Try setting a breakpoint there to investigate further. Could it be that the method is being called twice?

Regarding renameTo's javadoc:

Various aspects of this method's behavior depend on the platform: The rename operation may not be able to move a file across filesystems, may not be atomic, and may fail if a file with the destination path already exists. Always check the return value to ensure the rename operation was successful.

Answer 3

Answer №2

After running the wicket MultiUploadPage example, it's great to see everything functioning smoothly. Can you provide more insight into your page structure and what sets it apart?

WicketApplication.java

public class WicketApplication extends WebApplication {

    private Folder uploadFolder = null;

    @Override
    public Class<? extends WebPage> getHomePage(){
        return HomePage.class;
    }

    public Folder getUploadFolder(){
        return uploadFolder;
    }

    @Override
    public void init(){
        super.init();
        getResourceSettings().setThrowExceptionOnMissingResource(false);
        uploadFolder = new Folder(System.getProperty("java.io.tmpdir"), "wicket-uploads");
        uploadFolder.mkdirs();
        getApplicationSettings().setUploadProgressUpdatesEnabled(true);
    }
}

HomePage.java

public class HomePage extends WebPage {

private static final long serialVersionUID = 1L;
private final FileListView fileListView;

public HomePage(final PageParameters parameters){
    Folder uploadFolder = getUploadFolder();

    final FeedbackPanel uploadFeedback = new FeedbackPanel("uploadFeedback");
    add(uploadFeedback);

    final FileUploadForm simpleUploadForm = new FileUploadForm("simpleUpload");
    add(simpleUploadForm);

    add(new Label("dir", uploadFolder.getAbsolutePath()));
    fileListView = new FileListView("fileList", new LoadableDetachableModel<List<File>>(){

        private static final long serialVersionUID = 1L;

        @Override
        protected List<File> load(){
            return Arrays.asList(getUploadFolder().listFiles());
        }
    });
    add(fileListView);
}

private class FileListView extends ListView<File>{
    private static final long serialVersionUID = 1L;

    public FileListView(String name, final IModel<List<File>> files){
        super(name, files);
    }

    @Override
    protected void populateItem(ListItem<File> listItem){
        final File file = listItem.getModelObject();
        listItem.add(new Label("file", file.getName()));
        listItem.add(new Link<Void>("delete"){
            private static final long serialVersionUID = 1L;

            @Override
            public void onClick(){
                Files.remove(file);
                info("Deleted " + file);
            }
        });
    }
}

private class FileUploadForm extends Form<Void>{
    private static final long serialVersionUID = 1L;
    private final Collection<FileUpload> uploads = new ArrayList<FileUpload>();

    public FileUploadForm(String name){
        super(name);
        setMultiPart(true);
        add(new MultiFileUploadField("fileInput", new PropertyModel<Collection<FileUpload>>(this, "uploads"), 5, true));
        setMaxSize(Bytes.kilobytes(100000));
    }

    @Override
    protected void onSubmit(){
        for (FileUpload upload : uploads){
            File newFile = new File(getUploadFolder(), upload.getClientFileName());
            try{
                newFile.createNewFile();
                upload.writeTo(newFile);
                HomePage.this.info("saved file: " + upload.getClientFileName());
            } catch (Exception e){
                throw new IllegalStateException("Unable to write file");
            }
        }
    }
}

private Folder getUploadFolder(){
    return ((WicketApplication) Application.get()).getUploadFolder();
}

}

HomePage.html

    <!DOCTYPE html>
<html xmlns:wicket="http://wicket.apache.org">
    <head>
        <meta charset="utf-8" />
        <title>Apache Wicket Quickstart</title>
        <link rel="stylesheet" href="style.css" type="text/css" media="screen" title="Stylesheet" />
    </head>
    <body>
        Running the multi upload field has been successful thanks to the javascript discovered at
        <a target="_blank" href="http://the-stickman.com/web-development/javascript/upload-multiple-files-with-a-single-file-element/">here</a>.
        <br />
        <br /> Wicket is capable of handling file uploads via AJAX as well, a feature covered in the AJAX
        examples section. However, this example does not include AJAX Functionality to maintain simplicity.
        <br />
        <br />

        <form wicket:id="simpleUpload">
            <fieldset>
                <legend>Upload form</legend>
                <p>
                <div wicket:id="fileInput" class="mfuex" />
                </p>
                <input type="submit" value="Upload!" />
            </fieldset>
        </form>

        <div><span wicket:id="uploadFeedback" /></div>

        <div>
            <h4>Current files in <span wicket:id="dir">(dir)</span>:</h4>
            <table>
                <tr wicket:id="fileList">
                    <td width="200"><span wicket:id="file">(file)</span></td>
                    <td><a href="#" wicket:id="delete"><img src="delete.gif" border="0" /></a></td>
                </tr>
            </table>
        </div>
    </body>
</html>

Answer 4

After running the wicket MultiUploadPage example, it's great to see everything functioning smoothly. Can you provide more insight into your page structure and what sets it apart?

WicketApplication.java

public class WicketApplication extends WebApplication {

    private Folder uploadFolder = null;

    @Override
    public Class<? extends WebPage> getHomePage(){
        return HomePage.class;
    }

    public Folder getUploadFolder(){
        return uploadFolder;
    }

    @Override
    public void init(){
        super.init();
        getResourceSettings().setThrowExceptionOnMissingResource(false);
        uploadFolder = new Folder(System.getProperty("java.io.tmpdir"), "wicket-uploads");
        uploadFolder.mkdirs();
        getApplicationSettings().setUploadProgressUpdatesEnabled(true);
    }
}

HomePage.java

public class HomePage extends WebPage {

private static final long serialVersionUID = 1L;
private final FileListView fileListView;

public HomePage(final PageParameters parameters){
    Folder uploadFolder = getUploadFolder();

    final FeedbackPanel uploadFeedback = new FeedbackPanel("uploadFeedback");
    add(uploadFeedback);

    final FileUploadForm simpleUploadForm = new FileUploadForm("simpleUpload");
    add(simpleUploadForm);

    add(new Label("dir", uploadFolder.getAbsolutePath()));
    fileListView = new FileListView("fileList", new LoadableDetachableModel<List<File>>(){

        private static final long serialVersionUID = 1L;

        @Override
        protected List<File> load(){
            return Arrays.asList(getUploadFolder().listFiles());
        }
    });
    add(fileListView);
}

private class FileListView extends ListView<File>{
    private static final long serialVersionUID = 1L;

    public FileListView(String name, final IModel<List<File>> files){
        super(name, files);
    }

    @Override
    protected void populateItem(ListItem<File> listItem){
        final File file = listItem.getModelObject();
        listItem.add(new Label("file", file.getName()));
        listItem.add(new Link<Void>("delete"){
            private static final long serialVersionUID = 1L;

            @Override
            public void onClick(){
                Files.remove(file);
                info("Deleted " + file);
            }
        });
    }
}

private class FileUploadForm extends Form<Void>{
    private static final long serialVersionUID = 1L;
    private final Collection<FileUpload> uploads = new ArrayList<FileUpload>();

    public FileUploadForm(String name){
        super(name);
        setMultiPart(true);
        add(new MultiFileUploadField("fileInput", new PropertyModel<Collection<FileUpload>>(this, "uploads"), 5, true));
        setMaxSize(Bytes.kilobytes(100000));
    }

    @Override
    protected void onSubmit(){
        for (FileUpload upload : uploads){
            File newFile = new File(getUploadFolder(), upload.getClientFileName());
            try{
                newFile.createNewFile();
                upload.writeTo(newFile);
                HomePage.this.info("saved file: " + upload.getClientFileName());
            } catch (Exception e){
                throw new IllegalStateException("Unable to write file");
            }
        }
    }
}

private Folder getUploadFolder(){
    return ((WicketApplication) Application.get()).getUploadFolder();
}

}

HomePage.html

    <!DOCTYPE html>
<html xmlns:wicket="http://wicket.apache.org">
    <head>
        <meta charset="utf-8" />
        <title>Apache Wicket Quickstart</title>
        <link rel="stylesheet" href="style.css" type="text/css" media="screen" title="Stylesheet" />
    </head>
    <body>
        Running the multi upload field has been successful thanks to the javascript discovered at
        <a target="_blank" href="http://the-stickman.com/web-development/javascript/upload-multiple-files-with-a-single-file-element/">here</a>.
        <br />
        <br /> Wicket is capable of handling file uploads via AJAX as well, a feature covered in the AJAX
        examples section. However, this example does not include AJAX Functionality to maintain simplicity.
        <br />
        <br />

        <form wicket:id="simpleUpload">
            <fieldset>
                <legend>Upload form</legend>
                <p>
                <div wicket:id="fileInput" class="mfuex" />
                </p>
                <input type="submit" value="Upload!" />
            </fieldset>
        </form>

        <div><span wicket:id="uploadFeedback" /></div>

        <div>
            <h4>Current files in <span wicket:id="dir">(dir)</span>:</h4>
            <table>
                <tr wicket:id="fileList">
                    <td width="200"><span wicket:id="file">(file)</span></td>
                    <td><a href="#" wicket:id="delete"><img src="delete.gif" border="0" /></a></td>
                </tr>
            </table>
        </div>
    </body>
</html>

Error handling issues with multiple file uploads in Wicket: FileNotFoundException

Answer №1

Answer №2

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