Java - Load file as Template + append content in memory and manage byte[]

Question

Im trying load a file in memory with a base information, append lines and include the result into a Zip file. In C# existes MemoryStream but, in java not.

the context of my application is load a stylesheet.css files with a pre-defined styles for add other styles that i get dinamically. Later i want add this content to a zip entry, and i need a byte[] that represent this content.

For the moment, i have the next lines, but i dont know as convert this to byte[]:

ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
File file = new File(classLoader.getResource("style.css").getFile());

OutputStreamWriter osw = new OutputStreamWriter( new FileOutputStream( file ) );
BufferedWriter writer = new BufferedWriter(osw);

I tried, with ByteArrayOutputStream but i can't completed all my requirements.

Any idea? im opne to other ideas for get my goal. I looking for CSSParser too, but i didn't see as I can append content and get a File document (byte[]) for to add to my zip file.

Answer 1

Finnaly, i didn't find other solution for my problem that convert the InputStream to ByteArrayOutputStream byte to byte.

I created the following methods:

Load template file into Input Stream and convert.

private ByteArrayOutputStream getByteArrayOutputStreamFor(String templateName) {
    try {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        InputStream inStream = classLoader.getResourceAsStream( templateName ); //file into resources directory
        ByteArrayOutputStream baos = Utils.toOutputStream(inStream);

        return baos;

    } catch (Exception e) {
        String msg = String.format("erro to loaf filetemplate {%s}: %s", templateName, e.getMessage());
        throw new RuntimeException( msg, e.getCause() );
    }
}

Copy the inputStream into a ByteArrayOutputStream byte to byte

public static final ByteArrayOutputStream toOutputStream(InputStream inStream) {
    try {
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();

        int byteReads;
        while ((byteReads = inStream.read()) != -1) {
            outStream.write(byteReads);
        }

        outStream.flush();
        inStream.close();

        return outStream;

    } catch (Exception e) {
        throw new RuntimeException("error message");
    }
}

Finally, I append text to ByteArrayOutputStream

ByteArrayOutputStream baosCSS = getByteArrayOutputStreamFor( "templateName.css" );
BufferedWriter writer = new BufferedWriter( new OutputStreamWriter( baosCSS ) );
writer.append( "any text" );
writer.flush();
writer.close();

byte[] bytes = baosCSS.toByteArray()