在glide库和RoundedBitmapDrawableFactory类的帮助下，很容易实现。您可能需要创建圆形占位符映像。

    Glide.with(context)
        .load(imgUrl)
        .asBitmap()
        .placeholder(R.drawable.placeholder)
        .error(R.drawable.placeholder)
        .into(new BitmapImageViewTarget(imgProfilePicture) {
            @Override
            protected void setResource(Bitmap resource) {
                RoundedBitmapDrawable drawable = RoundedBitmapDrawableFactory.create(context.getResources(),
                        Bitmap.createScaledBitmap(resource, 50, 50, false));
                drawable.setCornerRadius(10); //drawable.setCircular(true);
                imgProfilePicture.setImageDrawable(drawable);
            }
        });

我使用路径在图像画布上只画角。(我需要没有位图内存分配的解决方案)

@Override
protected void onDraw(final Canvas canvas) {
    super.onDraw(canvas);

    if (!hasRoundedCorners()) return;

    mPaint.setStyle(Paint.Style.FILL);
    mPaint.setStrokeWidth(0);

    Path path = new Path();
    path.setFillType(Path.FillType.INVERSE_WINDING);
    path.addRoundRect(new RectF(0, 0, getWidth(), getHeight()), mRadius, mRadius, Path.Direction.CCW);
    canvas.drawPath(path, mPaint);
}

注意，你不应该在onDraw方法中分配任何新对象。此代码是概念验证，不应该在产品代码中这样使用

看到更多: https://medium.com/@przemek.materna/rounded-image-view-no-bitmap-reallocation-11a8b163484d

以下是我的解决方案:

<com.myproject.ui.RadiusCornerImageView
        android:id="@+id/imageViewPhoto"
        android:layout_width="160dp"
        android:layout_height="160dp"
        app:corner_radius_dp="5"
        app:corner_radius_position="top"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

在java代码中:

public class RadiusCornerImageView extends android.support.v7.widget.AppCompatImageView {
    private int cornerRadiusDP = 0; // dp
    private int corner_radius_position;

    public RadiusCornerImageView(Context context) {
        super(context);
    }

    public RadiusCornerImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RadiusCornerImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        TypedArray typeArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.RadiusCornerImageView, 0, 0);
        try {
            cornerRadiusDP = typeArray.getInt(R.styleable.RadiusCornerImageView_corner_radius_dp, 0);
            corner_radius_position = typeArray.getInteger(R.styleable.RadiusCornerImageView_corner_radius_position, 0);
        } finally {
            typeArray.recycle();
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        float radiusPx = AndroidUtil.dpToPx(getContext(), cornerRadiusDP);
        Path clipPath = new Path();
        RectF rect = null;
        if (corner_radius_position == 0) { // all
            // round corners on all 4 angles
            rect = new RectF(0, 0, this.getWidth(), this.getHeight());
        } else if (corner_radius_position == 1) {
            // round corners only on top left and top right
            rect = new RectF(0, 0, this.getWidth(), this.getHeight() + radiusPx);

    } else {
        throw new IllegalArgumentException("Unknown corner_radius_position = " + corner_radius_position);
    }
    clipPath.addRoundRect(rect, radiusPx, radiusPx, Path.Direction.CW);
    canvas.clipPath(clipPath);
    super.onDraw(canvas);
 }
}

下面是一个覆盖imageView的简单示例，然后你也可以在布局设计器中使用它来预览。

public class RoundedImageView extends ImageView {

    public RoundedImageView(Context context) {
        super(context);
    }

    public RoundedImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public RoundedImageView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public void setImageDrawable(Drawable drawable) {
        float radius = 0.1f;
        Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap();
        RoundedBitmapDrawable rid = RoundedBitmapDrawableFactory.create(getResources(), bitmap);
        rid.setCornerRadius(bitmap.getWidth() * radius);
        super.setImageDrawable(rid);
    }
}

这是为了快速解决问题。半径用于所有角落，并基于位图宽度的百分比。

我只是覆盖了setImageDrawable，并使用支持v4方法绘制圆角位图。

用法:

<com.example.widgets.RoundedImageView
        android:layout_width="39dp"
        android:layout_height="39dp"
        android:src="@drawable/your_drawable" />

使用imageView和自定义imageView预览:

另一种简单的方法是使用一个带有角半径的CardView和一个ImageView在里面:

  <androidx.cardview.widget.CardView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:cardCornerRadius="8dp"
            android:layout_margin="5dp"
            android:elevation="10dp">

            <ImageView
                android:id="@+id/roundedImageView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:src="@drawable/image"
                android:background="@color/white"
                android:scaleType="centerCrop"
                />
        </androidx.cardview.widget.CardView>

我的ImageView圆角小部件的实现，(下||上)大小图像到所需的尺寸。它利用了CaspNZ的代码形式。

public class ImageViewRounded extends ImageView {

    public ImageViewRounded(Context context) {
        super(context);
    }

    public ImageViewRounded(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ImageViewRounded(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        BitmapDrawable drawable = (BitmapDrawable) getDrawable();

        if (drawable == null) {
            return;
        }

        if (getWidth() == 0 || getHeight() == 0) {
            return; 
        }

        Bitmap fullSizeBitmap = drawable.getBitmap();

        int scaledWidth = getMeasuredWidth();
        int scaledHeight = getMeasuredHeight();

        Bitmap mScaledBitmap;
        if (scaledWidth == fullSizeBitmap.getWidth() && scaledHeight == fullSizeBitmap.getHeight()) {
            mScaledBitmap = fullSizeBitmap;
        } else {
            mScaledBitmap = Bitmap.createScaledBitmap(fullSizeBitmap, scaledWidth, scaledHeight, true /* filter */);
        }

        Bitmap roundBitmap = ImageUtilities.getRoundedCornerBitmap(getContext(), mScaledBitmap, 5, scaledWidth, scaledHeight,
                false, false, false, false);
        canvas.drawBitmap(roundBitmap, 0, 0, null);

    }

}