Read full tutorial on how to convert org.apache.myfaces.trinidad.model to java.io.File here :

uploadedFileToFileConverter.java

public static File uploadedFileToFileConverter(UploadedFile uf) {
    InputStream inputStream = null;
    OutputStream outputStream = null;
    //Add you expected file encoding here:
    System.setProperty("file.encoding", "UTF-8");
    File newFile = new File(uf.getFilename());
    try {
        inputStream = uf.getInputStream();
        outputStream = new FileOutputStream(newFile);
        int read = 0;
        byte[] bytes = new byte[1024];
        while ((read = inputStream.read(bytes)) != -1) {
            outputStream.write(bytes, 0, read);
        }
    } catch (IOException e) {
       //Do something with the Exception (logging, etc.)
    }
    return newFile;
}