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, "葉應是葉" + "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();
  // 水印顏色
  p.setColor(Color.parseColor("#c5576370"));
  // 水印字體大小
  p.setTextSize(150);
  //抗鋸齒
  p.setAntiAlias(true);
  //繪制圖像
  canvas.drawBitmap(bitmap, 0, 0, p);
  //繪制文字
  canvas.drawText(mark, 0, h / 2, p);
  canvas.save(Canvas.ALL_SAVE_FLAG);
  canvas.restore();
  return bmp;
 }

}