ถ้าจะใช้ java สร้าง QRcode ต้องเขียนยังไงอะครับ (ในกรณีนี้ผมไม่เคยเขียนjavaมาก่อนเลยอะครับ เคยใช้แต่ตัวอื่น)

public static void main(String[] args) {
    Charset charset = Charset.forName("ISO-8859-1");
    CharsetEncoder encoder = charset.newEncoder();
    byte[] b = null;
    try {
        // Convert a string to ISO-8859-1 bytes in a ByteBuffer
        ByteBuffer bbuf = encoder.encode(CharBuffer.wrap("hello world"));
        b = bbuf.array();
    } catch (CharacterCodingException e) {
        System.out.println(e.getMessage());
    }

    String data;
    try {
        data = new String(b, "ISO-8859-1");
    } catch (UnsupportedEncodingException e) {
        System.out.println(e.getMessage());
    }

    // get a byte matrix for the data
    BitMatrix matrix = null;
    int h = 100;
    int w = 100;
    com.google.zxing.Writer writer = new QRCodeWriter();
    try {
        matrix = writer.encode(data,
        com.google.zxing.BarcodeFormat.QR_CODE, w, h);
    } catch (com.google.zxing.WriterException e) {
        System.out.println(e.getMessage());
    }

    String filePath = "C:\\temp\\qr_png.png";
    File file = new File(filePath);
    try {
        MatrixToImageWriter.writeToFile(matrix, "PNG", file);
        System.out.println("printing to " + file.getAbsolutePath());
    } catch (IOException e) {
        System.out.println(e.getMessage());
    }
}