直接上代码：

public class MainActivity extends Activity {
    private TextView tv;
    private ImageView iv;
    private int QR_WIDTH, QR_HEIGHT;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv = (TextView) findViewById(R.id.tv);
        iv = (ImageView) findViewById(R.id.iv);
        QR_WIDTH = 300;
        QR_HEIGHT = 300;
        createImage();
    }
    // 生成QR图
    private void createImage() {
        try {
            // 需要引入core包
            QRCodeWriter writer = new QRCodeWriter();
            String text = tv.getText().toString();
            if (text == null || "".equals(text) || text.length() < 1) {
                return;
            }
            // 把输入的文本转为二维码
            BitMatrix martix = writer.encode(text, BarcodeFormat.QR_CODE,
                    QR_WIDTH, QR_HEIGHT);
            Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();
            hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
            BitMatrix bitMatrix = new QRCodeWriter().encode(text,
                    BarcodeFormat.QR_CODE, QR_WIDTH, QR_HEIGHT, hints);
            int[] pixels = new int[QR_WIDTH * QR_HEIGHT];
            for (int y = 0; y < QR_HEIGHT; y++) {
                for (int x = 0; x < QR_WIDTH; x++) {
                    if (bitMatrix.get(x, y)) {
                        pixels[y * QR_WIDTH + x] = 0xff000000;
                    } else {
                        pixels[y * QR_WIDTH + x] = 0xffffffff;
                    }
                }
            }
            Bitmap bitmap = Bitmap.createBitmap(QR_WIDTH, QR_HEIGHT,
                    Bitmap.Config.ARGB_8888);
            bitmap.setPixels(pixels, 0, QR_WIDTH, 0, 0, QR_WIDTH, QR_HEIGHT);
            iv.setImageBitmap(bitmap);
        } catch (WriterException e) {
            e.printStackTrace();
        }
    }
}


要注意，需要导入一个core.jar包。见附件