Android 通过inputstream 加载非Drawable 文件夹下的 .9 path 图片

有时候我们想在其他地方加载 .9 path 图片，比如 assets 目录下，又或者从网上下载一个到sdcard 上，但是 bitmap.getNinePatchChunk() 总是 return null，而如果9path图片在drawable 文件下则可以。为什么会这样呢？是因为9path 图片有两种type，一种叫“source” 一种叫“compiled”. “source” 就是我们通过android sdk 工具制作好的9path 图片，“compiled” 就是打包apk 的时候aapt 会对9path图片进行编译。这就是我们为什么能使用drawable 下的9path图片，所以如果我们想在其他地方也正常使用9path 图片，那么我们就得事先对其进行compile，把编译好的在放在assets 目录或者其他地方。

编译命令 ： aapt c -S nine_path_file_floder -C output_floder

// 加载9path并设置background
 Bitmap bitmap =IconUtils.getBitmapFromFile("assets/easou_ecom_mads_bg_down.9.png");
            final byte[] chunk = bitmap.getNinePatchChunk();
            if (NinePatch.isNinePatchChunk(chunk)) {
                bottomLayout.setBackgroundDrawable(new NinePatchDrawable(getContext().getResources(), bitmap, chunk, NinePatchChunk.deserialize(chunk).mPaddings, null));
            }

//IconUtils.class        
public static Bitmap getBitmapFromFile(String fileName) {
        InputStream is = IconUtils.class.getClassLoader().getResourceAsStream(fileName);
        return BitmapFactory.decodeStream(is);
    }

//NinePatchChunk.class
public class NinePatchChunk {
    public static final int NO_COLOR = 0x00000001;
    public static final int TRANSPARENT_COLOR = 0x00000000;

    public final Rect mPaddings = new Rect();

    public int mDivX[];
    public int mDivY[];
    public int mColor[];

    private static void readIntArray(final int[] data, final ByteBuffer buffer) {
        for (int i = 0, n = data.length; i < n; ++i)
            data[i] = buffer.getInt();
    }

    private static void checkDivCount(final int length) {
        if (length == 0 || (length & 0x01) != 0)
            throw new RuntimeException("invalid nine-patch: " + length);
    }

    public static NinePatchChunk deserialize(final byte[] data) {
        final ByteBuffer byteBuffer =ByteBuffer.wrap(data).order(ByteOrder.nativeOrder());

        if (byteBuffer.get() == 0) return null; // is not serialized

        final NinePatchChunk chunk = new NinePatchChunk();
        chunk.mDivX = new int[byteBuffer.get()];
        chunk.mDivY = new int[byteBuffer.get()];
        chunk.mColor = new int[byteBuffer.get()];

        checkDivCount(chunk.mDivX.length);
        checkDivCount(chunk.mDivY.length);

        // skip 8 bytes
        byteBuffer.getInt();
        byteBuffer.getInt();

        chunk.mPaddings.left = byteBuffer.getInt();
        chunk.mPaddings.right = byteBuffer.getInt();
        chunk.mPaddings.top = byteBuffer.getInt();
        chunk.mPaddings.bottom = byteBuffer.getInt();

        // skip 4 bytes
        byteBuffer.getInt();

        readIntArray(chunk.mDivX, byteBuffer);
        readIntArray(chunk.mDivY, byteBuffer);
        readIntArray(chunk.mColor, byteBuffer);

        return chunk;
    }
}