zxing 3.0.1生成二维码

    zxing 3.0.1生成二维码，这么写怎么就是不对，MatrixToImageWriter类找不到，应该怎么写？
    String contents = "今天，我们来简单聊聊google开源项目——ZXing（二维条码编解码）";  

    Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();  

    hints.put(EncodeHintType.CHARACTER_SET, "GBK");  

    BitMatrix matrix = null;  

    try {  

        matrix = new MultiFormatWriter().encode(contents,  
                BarcodeFormat.QR_CODE, 300, 300, hints);  

    } catch (WriterException e) {  

        e.printStackTrace();  

    }  

    File file = new File("D://qrcodeImage.png");  

    try {  

        MatrixToImageWriter.writeToFile(matrix, "png", file);  


    } catch (IOException e) {  

        e.printStackTrace();  

    }

Class MatrixToImageWriter是在com.google.zxing.client.j2se包下面的，导入这个包试试