分享一个Android设置圆形图片的特别方法

<android.support.v7.widget.CardView
 android:id="@+id/cv_img_activity"
 android:layout_width="200dp"
 android:layout_height="200dp"
 app:cardCornerRadius="100dp"
 app:cardElevation="10dp"
 app:cardPreventCornerOverlap="true">

 <ImageView
  android:id="@+id/iv_cv_img_activity"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:scaleType="centerCrop"/>
 <TextView
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:textColor="@color/colorAccent"
  android:textSize="30sp"
  android:layout_gravity="bottom|center_horizontal"
  android:text="圆"/>
</android.support.v7.widget.CardView>

public class ImgActivity extends AppCompatActivity {
 private static final String url = "https://timgsa.baidu.com/timg?image&quality=80&size=b10000_10000&sec=1473082549776&di=cb9749bd976beb119da065ee56ebbc60&imgtype=jpg&src=http%3A%2F%2Fstatic.oneplus.cn%2Fdata%2Fattachment%2Fforum%2F201410%2F18%2F111437v9ll9869qqmq76n7.jpg";
 private CardView cardView;
 private ImageView iv_cv;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_img);
  init();
 }

 private void init() {
  cardView = (CardView) findViewById(R.id.cv_img_activity);
  iv_cv = (ImageView) findViewById(R.id.iv_cv_img_activity);
 }

 @Override
 public void onWindowFocusChanged(boolean hasFocus) {
  super.onWindowFocusChanged(hasFocus);
  if (hasFocus){
    Glide.with(ImgActivity.this).load(url).override(cardView.getWidth(),cardView.getHeight()).into(iv_cv);
  }
 }

}