安卓10（Android10API29）保存图片到相册DCIM/Camera

Posted 2022-11-06 Wei_Leng

大家都知道android10最大的变化可能就是Scoped Storage（分区存储）。对于把图片保存到相册的应用，影响就大了，因为这个功能在Android10的手机上就会出现异常了，今天就来说说如何兼容Android10保存图片到相册。

1、要存储权限

 protected void save() 
        AndPermission.with(getContext())
                .runtime()
                .permission(Permission.WRITE_EXTERNAL_STORAGE,Permission.READ_EXTERNAL_STORAGE)
                .onGranted(permissions -> 
                    Object uri = urls.get(isInfinite ? position % urls.size() : position);//图片地址
                    saveNetPic(getContext(),uri);position));
                )
                .onDenied(permissions -> 
                    ToastUtil.showLong("权限被拒绝！");
                )
                .start();
    

2、保存到本应用的文件目录下，这个步骤不需要权限

 private void saveNetPic(final Context mContext,Object uri)
        final Handler mainHandler = new Handler(Looper.getMainLooper());
        final ExecutorService executor = Executors.newSingleThreadExecutor();
        executor.execute(new Runnable() 
            @Override
            public void run() 
                File source = imageLoader.getImageFile(mContext, uri);
                try 
                    //1. create path
                    String dirPath = mContext.getExternalFilesDir(Environment.DIRECTORY_PICTURES).getAbsolutePath();
                    File dirFile = new File(dirPath);
                    if (!dirFile.exists()) dirFile.mkdirs();
                    ImageType type = ImageHeaderParser.getImageType(new FileInputStream(source));
                    String ext = getFileExt(type);
                    final File target = new File(dirPath, System.currentTimeMillis() + "." + ext);
                    if (target.exists()) target.delete();
                    target.createNewFile();
                    //2. save，保存到本应用目录
                    writeFileFromIS(target, new FileInputStream(source));
                    //3. notify
                    MediaScannerConnection.scanFile(mContext, new String[]target.getAbsolutePath(),
                            new String[]"image/" + ext, new MediaScannerConnection.OnScanCompletedListener() 
                                @Override
                                public void onScanCompleted(final String path, Uri uri) 
                                    mainHandler.post(new Runnable() 
                                        @Override
                                        public void run() 
                                            Toast.makeText(mContext, "已保存到相册！", Toast.LENGTH_SHORT).show();
                                            //4.保存到相册
                                            try 
                                                Bitmap bitmap = BitmapFactory.decodeFile(target.getAbsolutePath());
                                                saveBitmap(getContext(),bitmap);
                                             catch (Exception e) 
                                                e.printStackTrace();
                                            
                                        
                                    );
                                
                            );
                 catch (IOException e) 
                    e.printStackTrace();
                

            
        );
    

3、通过SAF的方式保存文件到任意位置

 public void saveBitmap(Context context, Bitmap  bitmap) 

        ContentValues values = new ContentValues();
        values.put(MediaStore.Images.Media.DESCRIPTION, "This is an image");
        values.put(MediaStore.Images.Media.DISPLAY_NAME, "Image.png");
        values.put(MediaStore.Images.Media.MIME_TYPE, "image/png");
        values.put(MediaStore.Images.Media.TITLE, System.currentTimeMillis()+".png");
        values.put(MediaStore.Images.Media.RELATIVE_PATH, "DCIM/Camera");

        Uri external = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        ContentResolver resolver = context.getContentResolver();

        Uri insertUri = resolver.insert(external, values);
        OutputStream os = null;
        if (insertUri != null) 
            try 
                os = resolver.openOutputStream(insertUri);
                bitmap.compress(Bitmap.CompressFormat.PNG, 90, os);
             catch (IOException e) 
                e.printStackTrace();
            finally 
                try 
                    if (os != null) 
                        os.close();
                    
                 catch (IOException e) 
                    e.printStackTrace();
                
            
        
    

其中写入文件流和判断图片格式的代码如下：
写入文件流

    private static boolean writeFileFromIS(final File file, final InputStream is) 
        OutputStream os = null;
        try 
            os = new BufferedOutputStream(new FileOutputStream(file));
            byte data[] = new byte[8192];
            int len;
            while ((len = is.read(data, 0, 8192)) != -1) 
                os.write(data, 0, len);
            
            return true;
         catch (IOException e) 
            e.printStackTrace();
            return false;
         finally 
            try 
                is.close();
             catch (IOException e) 
                e.printStackTrace();
            
            try 
                if (os != null) 
                    os.close();
                
             catch (IOException e) 
                e.printStackTrace();
            
        
    

判断图片类型：

private static String getFileExt(ImageType type) 
        switch (type) 
            case GIF:
                return "gif";
            case PNG:
            case PNG_A:
                return "png";
            case WEBP:
            case WEBP_A:
                return "webp";
            case JPEG:
                return "jpeg";
        
        return "jpeg";
    

还有个ImageHeaderParser来至 XPopup

import static com.lxj.xpopup.enums.ImageType.GIF;
import static com.lxj.xpopup.enums.ImageType.JPEG;
import static com.lxj.xpopup.enums.ImageType.PNG;
import static com.lxj.xpopup.enums.ImageType.PNG_A;
import static com.lxj.xpopup.enums.ImageType.UNKNOWN;

/**
 * Date: 2020/3/24
 * author: SmallCake
 */
public class ImageHeaderParser 
    private static final int GIF_HEADER = 0x474946;
    private static final int PNG_HEADER = 0x89504E47;
    static final int EXIF_MAGIC_NUMBER = 0xFFD8;
    // WebP-related
    // "RIFF"
    private static final int RIFF_HEADER = 0x52494646;
    // "WEBP"
    private static final int WEBP_HEADER = 0x57454250;
    // "VP8" null.
    private static final int VP8_HEADER = 0x56503800;
    private static final int VP8_HEADER_MASK = 0xFFFFFF00;
    private static final int VP8_HEADER_TYPE_MASK = 0x000000FF;
    // 'X'
    private static final int VP8_HEADER_TYPE_EXTENDED = 0x00000058;
    // 'L'
    private static final int VP8_HEADER_TYPE_LOSSLESS = 0x0000004C;
    private static final int WEBP_EXTENDED_ALPHA_FLAG = 1 << 4;
    private static final int WEBP_LOSSLESS_ALPHA_FLAG = 1 << 3;

    public static ImageType getImageType(InputStream is) throws IOException
        Reader reader = new StreamReader(is);
        final int firstTwoBytes = reader.getUInt16();

        // JPEG.
        if (firstTwoBytes == EXIF_MAGIC_NUMBER) 
            return JPEG;
        

        final int firstFourBytes = (firstTwoBytes << 16 & 0xFFFF0000) | (reader.getUInt16() & 0xFFFF);
        // PNG.
        if (firstFourBytes == PNG_HEADER) 
            // See: http://stackoverflow.com/questions/2057923/how-to-check-a-png-for-grayscale-alpha
            // -color-type
            reader.skip(25 - 4);
            int alpha = reader.getByte();
            // A RGB indexed PNG can also have transparency. Better safe than sorry!
            return alpha >= 3 ? PNG_A : PNG;
        

        // GIF from first 3 bytes.
        if (firstFourBytes >> 8 == GIF_HEADER) 
            return GIF;
        

        // WebP (reads up to 21 bytes). See https://developers.google.com/speed/webp/docs/riff_container
        // for details.
        if (firstFourBytes != RIFF_HEADER) 
            return UNKNOWN;
        
        // Bytes 4 - 7 contain length information. Skip these.
        reader.skip(4);
        final int thirdFourBytes =
                (reader.getUInt16() << 16 & 0xFFFF0000) | (reader.getUInt16() & 0xFFFF);
        if (thirdFourBytes != WEBP_HEADER) 
            return UNKNOWN;
        
        final int fourthFourBytes =
                (reader.getUInt16() << 16 & 0xFFFF0000) | (reader.getUInt16() & 0xFFFF);
        if ((fourthFourBytes & VP8_HEADER_MASK) != VP8_HEADER) 
            return UNKNOWN;
        
        if ((fourthFourBytes & VP8_HEADER_TYPE_MASK) == VP8_HEADER_TYPE_EXTENDED) 
            // Skip some more length bytes and check for transparency/alpha flag.
            reader.skip(4);
            return (reader.getByte() & WEBP_EXTENDED_ALPHA_FLAG) != 0 ? ImageType.WEBP_A : ImageType.WEBP;
        
        if ((fourthFourBytes & VP8_HEADER_TYPE_MASK) == VP8_HEADER_TYPE_LOSSLESS) 
            // See chromium.googlesource.com/webm/libwebp/+/master/doc/webp-lossless-bitstream-spec.txt
            // for more info.
            reader.skip(4);
            return (reader.getByte() & WEBP_LOSSLESS_ALPHA_FLAG) != 0 ? ImageType.WEBP_A : ImageType.WEBP;
        
        is.close();
        return ImageType.WEBP;
    
    private interface Reader 
        int getUInt16() throws IOException;
        short getUInt8() throws IOException;
        long skip(long total) throws IOException;
        int read(byte[] buffer, int byteCount) throws IOException;
        int getByte() throws IOException;
    
    private static final class StreamReader implements Reader 
        private final InputStream is;

        // Motorola / big endian byte order.
        StreamReader(InputStream is) 
            this.is = is;
        

        @Override
        public int getUInt16() throws IOException 
            return (is.read() << 8 & 0xFF00) | (is.read() & 0xFF);
        

        @Override
        public short getUInt8() throws IOException 
            return (short) (is.read() & 0xFF);
        

        @Override
        public long skip(long total) throws IOException 
            if (total < 0) 
                return 0;
            

            long toSkip = total;
            while (toSkip > 0) 
                long skipped = is.skip(toSkip);
                if (skipped > 0) 
                    toSkip -= skipped;
                 else 
                    // Skip has no specific contract as to what happens when you reach the end of
                    // the stream. To differentiate between temporarily not having more data and
                    // having finished the stream, we read a single byte when we fail to skip any
                    // amount of data.
                    int testEofByte = is.read();
                    if (testEofByte == -1) 
                        break;
                     else 
                        toSkip--;
                    
                
            
            return total - toSkip;
        

        @Override
        public int read(byte[] buffer, int byteCount) throws IOException 
            int toRead = byteCount;
            int read;
            while (toRead > 0 && ((read = is.read(buffer, byteCount - toRead, toRead)) != -1)) 
                toRead -= read;
            
            return byteCount - toRead;
        

        @Override
        public int getByte() throws IOException 
            return is.read();
        
    

参考：
OPPO - Android Q版本应用兼容性适配指导

作者：Small_Cake
链接：https://www.jianshu.com/p/cd9e58d1f8b9
来源：简书
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。

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