android - 为什么我创建的位图总是泄漏内存？

Question

我正在尝试使用 reflect 创建一个 drawable，这是我的代码:

public Drawable createReflectedImage(Drawable d) {

    int width = d.getIntrinsicWidth();
    int height = d.getIntrinsicHeight();
    Bitmap originalImage = Bitmap.createBitmap(width, height,
            Config.ARGB_8888);
    d.setBounds(0, 0, width, height);
    Canvas canvas = new Canvas(originalImage);
    d.draw(canvas);

    final int reflectionGap = 4;

    Matrix matrix = new Matrix();
    matrix.preScale(1, -1);

    Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0,
            height / 2, width, height / 2, matrix, false);

    Bitmap bitmapWithReflection = Bitmap.createBitmap(width,
            (height + height / 2), Config.ARGB_8888);

    canvas = new Canvas(bitmapWithReflection);

    canvas.drawBitmap(originalImage, 0, 0, null);

    Paint deafaultPaint = new Paint();
    canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);

    canvas.drawBitmap(reflectionImage, 0, height + reflectionGap, null);

    Paint paint = new Paint();
    LinearGradient shader = new LinearGradient(0,
            originalImage.getHeight(), 0, bitmapWithReflection.getHeight()
                    + reflectionGap, 0x70ffffff, 0x00ffffff,
            TileMode.MIRROR);

    paint.setShader(shader);

    paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));

    canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
            + reflectionGap, paint);
    BitmapDrawable drawable = new BitmapDrawable(getContext()
            .getResources(), bitmapWithReflection);
    originalImage.recycle();
    reflectionImage.recycle();
    return drawable;
}

每次调用 createReflectedImage 时都会显示以下日志，即使我只是在此函数末尾返回 null。

10-29 10:56:48.541: I/dalvikvm-heap(23989): Grow heap (frag case) to 19.332MB for 960016-byte allocation

谁能帮我弄清楚这个内存泄漏是怎么发生的？

Answer 1

这不是内存泄漏。每个 Android 设备都有每个应用程序的最大堆大小。出于性能原因，Android 不会为每个应用程序分配该大小，而是等到应用程序需要更多内存时再分配。您看到的这条消息是 DVM 在您的应用请求时分配更多内存，这是完全正常的。

在内存泄漏期间，您会看到 GC 启动得太频繁，这会在 logcat 中提示您消息。