public class MainActivity extends AppCompatActivity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ImageView iv = (ImageView) findViewById(R.id.imageView);
    Drawable drawable = ContextCompat.getDrawable(this, R.drawable.image);
    BitmapDrawable bd = (BitmapDrawable) drawable;
    Bitmap bmp = bd.getBitmap();
    Bitmap bitmap = createWatermark(bmp, "叶应是叶" + "http://blog.csdn.net/new_one_object");
    iv.setImageBitmap(bitmap);
  }

  private Bitmap createWatermark(Bitmap bitmap, String mark) {
    int w = bitmap.getWidth();
    int h = bitmap.getHeight();
    Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bmp);
    Paint p = new Paint();
    // 水印颜色
    p.setColor(Color.parseColor("#c5576370"));
    // 水印字体大小
    p.setTextSize(150);
    //抗锯齿
    p.setAntiAlias(true);
    //绘制图像
    canvas.drawBitmap(bitmap, 0, 0, p);
    //绘制文字
    canvas.drawText(mark, 0, h / 2, p);
    canvas.save(Canvas.ALL_SAVE_FLAG);
    canvas.restore();
    return bmp;
  }

}