Android开发中碰到的异常

1.java.lang.IllegalStateException: Can't compress a recycled bitmap

public static String scaleImage(int maxWidth, File imageFile, String cacheDir) {
        String path = imageFile.getPath();
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(path, options);
        DebugLog.e(TAG, "scaleImage::: maxWidth" + maxWidth + "; bmp.width=" + options.outWidth + ";" + imageFile.getPath());
        Bitmap bmp = null;
        if (options.outWidth <= maxWidth) {
            return path;
        } else if (options.outWidth > 4800) {
            options.inJustDecodeBounds = false;
            options.inSampleSize = 4;
            bmp = BitmapFactory.decodeFile(path, options);
        } else if (options.outWidth > 2400) {
            options.inJustDecodeBounds = false;
            options.inSampleSize = 2;
            bmp = BitmapFactory.decodeFile(path, options);
        } else {
            options.inJustDecodeBounds = false;
            bmp = BitmapFactory.decodeFile(path);
        }

        Matrix matrix = new Matrix();
        float scale = maxWidth * 1.0f / options.outWidth;
        matrix.setScale(scale, scale);
        Bitmap newBmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, false);
        bmp.recycle();
        bmp = null;
        DebugLog.e(TAG, "scaleImage::: newBmp.height=" + newBmp.getHeight() + "; newBmp.width=" + newBmp.getWidth());
        //压缩图片
        String newFileName = "k_" + System.nanoTime() + "_book" + getImageType(imageFile.getPath());
        File newImageFile = new File(cacheDir, newFileName);
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(newImageFile);
            newBmp.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            path = newImageFile.getPath();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            closeStream(null, fos);
        }
        return path;
    }

出现异常的代码是

        Bitmap newBmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, false);
        bmp.recycle();

我们看一下Bitmap.createBitmap()的源码

    public static Bitmap createBitmap(@NonNull Bitmap source, int x, int y, int width, int height,
            @Nullable Matrix m, boolean filter) {

        checkXYSign(x, y);
        checkWidthHeight(width, height);
        if (x + width > source.getWidth()) {
            throw new IllegalArgumentException("x + width must be <= bitmap.width()");
        }
        if (y + height > source.getHeight()) {
            throw new IllegalArgumentException("y + height must be <= bitmap.height()");
        }

        // check if we can just return our argument unchanged
        if (!source.isMutable() && x == 0 && y == 0 && width == source.getWidth() &&
                height == source.getHeight() && (m == null || m.isIdentity())) {
            return source;
        }

        boolean isHardware = source.getConfig() == Config.HARDWARE;
        if (isHardware) {
            source.noteHardwareBitmapSlowCall();
            source = nativeCopyPreserveInternalConfig(source.mNativePtr);
        }
      ........

原图和创建的图片如果宽高一样的情况下，可能直接会返回原图，所以生成的图片和原图有可能是同一个对象。
在代码中添加判断，修改如下：

        Bitmap newBmp = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, false);
        if (newBmp != bmp)
            bmp.recycle();