public class MainActivity extends AppCompatActivity { private ImageView mImgRectRound; private ImageView mImgRound; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  mImgRectRound = (ImageView) findViewById(R.id.img_rect_rounded);  mImgRound = (ImageView) findViewById(R.id.img_rounded);  rectRoundBitmap();  roundBitmap(); } private void rectRoundBitmap(){  //得到資源文件的BitMap  Bitmap image= BitmapFactory.decodeResource(getResources(),R.drawable.dog);  //創建RoundedBitmapDrawable對象  RoundedBitmapDrawable roundImg =RoundedBitmapDrawableFactory.create(getResources(),image);  //抗鋸齒  roundImg.setAntiAlias(true);  //設置圓角半徑  roundImg.setCornerRadius(30);  //設置顯示圖片  mImgRectRound.setImageDrawable(roundImg); } private void roundBitmap(){  //如果是圓的時候，我們應該把bitmap圖片進行剪切成正方形， 然后再設置圓角半徑為正方形邊長的一半即可  Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.dog);  Bitmap bitmap = null;  //將長方形圖片裁剪成正方形圖片  if (image.getWidth() == image.getHeight()) {   bitmap = Bitmap.createBitmap(image, image.getWidth() / 2 - image.getHeight() / 2, 0, image.getHeight(), image.getHeight());  } else {   bitmap = Bitmap.createBitmap(image, 0, image.getHeight() / 2 - image.getWidth() / 2, image.getWidth(), image.getWidth());  }  RoundedBitmapDrawable roundedBitmapDrawable = RoundedBitmapDrawableFactory.create(getResources(), bitmap);  //圓角半徑為正方形邊長的一半  roundedBitmapDrawable.setCornerRadius(bitmap.getWidth() / 2);  //抗鋸齒  roundedBitmapDrawable.setAntiAlias(true);  mImgRound.setImageDrawable(roundedBitmapDrawable); }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="com.cjl.roundedbitmap.MainActivity"> <ImageView  android:id="@+id/img_rect_rounded"  android:layout_width="200dp"  android:layout_height="300dp"  android:layout_marginTop="20dp"  android:layout_gravity="center_horizontal"/> <ImageView  android:id="@+id/img_rounded"  android:layout_marginTop="20dp"  android:layout_width="200dp"  android:layout_height="200dp"  android:layout_gravity="center_horizontal"/></LinearLayout>