File Upload

Mentawai makes it very easy to upload a file, abstracting any complexity away from the developer.

Setting up the file field in the HTML form:

<mtw:form action="HelloFileUpload.mtw" method="post" enctype="multipart/form-data">

Enter an username: <mtw:input name="username" size="25" /><br/>

Enter filename: <input name="theFile" type="file" /><br/>

<input type="submit" value="Enviar">

</mtw:form>

Setting up the file upload for an action in the application manager:

        action("/File", FileAction.class, "upload")
            .fileUpload()
            .on(SUCCESS, redir(mainAction));

The fileUpload() method has other options that you can use to fine-tune the upload process:

fileUpload(int maxInMemorySize); // <=== will write to disk once the limit is reached...

fileUpload(int maxInMemorySize, int maxSizeToThrowError); // <=== so the user does not try to upload a 10Gb file...

fileUpload(int maxInMemorySize, String tempDirInsideWebInf); // <=== directory where temp files will be stored...

fileUpload(int maxInMemorySize, int maxSizeToThrowError, String tempDirInsideWebInf);

Getting the file inside the action:

	public String upload() throws IOException {

		FileUpload fileUpload = (FileUpload) input.getValue("theFile");
		
		File file = getDestinationFile(fileUpload.getOriginalFilename()); // choose somehow the destination filename here

		FileOutputStream fos = new FileOutputStream(file); // the destination

		InputStream is = fileUpload.getInpuStream(); // the upload input stream
		byte[] data = new byte[4096];
		int read;
		while((read = is.read(data)) != -1) {
			fos.write(data, 0, read);
		}
		is.close();
		fos.close();
		
		fileUpload.deleteTempFile(); // get rid of the temp file if present... (optional because it will happen eventually)

		return SUCCESS;
	}

More methods you can use from the FileUpload object:

	public void deleteTempFile();

	public byte[] toByteArray();

	public String getContentType();

	public String getFieldName();

	public String getOriginalFilename();

	public long getSize();

	public String asString();

	public String asString(String encoding);

	public boolean isInMemory();

	public InputStream getInpuStream();	

	public FileItem getFileItem(); // the underlying Apache Commons FileItem object