像Whatsapp和Android上的其他信使一样的图像压缩

时间:2014-11-14 11:06:24

标签: android compression

我使用以下代码进行图像压缩。

代码压缩大于2 MB的图像文件。

但是这段代码需要时间和图像质量保持纯净。

public static String compressImage(String imagePath, Context context)
    {
        String resizeImagePath = null;
        String filePath = imagePath;
        CustomLogHandler.printDebug(TAG, "resizeImagePath:" + imagePath);
        Bitmap scaledBitmap = null;
        int imageScal = 1;

        // File size greater then 2mb
        DecimalFormat df = new DecimalFormat("0.00");
        File imgFile = new File(filePath);
        double bytes = imgFile.length();
        double kilobytes = (bytes / 1024);
        double megabytes = (kilobytes / 1024);

        AppConfig.makeLog(TAG, "image size in mb:" + df.format(megabytes), 0);

        double filesize = Double.parseDouble(df.format(megabytes));
        if (filesize > 2.00f)
        {

            for (int i = 0; i < filesize; i = i + 2)
            {

                imageScal++;
            }
            int remind = imageScal / 2;
            if (remind != 0)
            {
                imageScal = imageScal + 1;
            }

            makeLog(TAG, "image scale:" + imageScal, 0);

            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            Bitmap bmp = BitmapFactory.decodeFile(filePath, options);

            int actualHeight = options.outHeight;
            int actualWidth = options.outWidth;
            float maxHeight = 4000;
            float maxWidth = 6000;
            // float imgRatio = actualWidth / actualHeight;
            // float maxRatio = maxWidth / maxHeight;

            if (actualHeight > maxHeight)
            {
                imageScal = imageScal + 4;
            }

            if (actualWidth > maxWidth)
            {
                imageScal = imageScal + 8;
            }

            // if (actualHeight > maxHeight || actualWidth > maxWidth)
            // {
            // if (imgRatio < maxRatio)
            // {
            // imgRatio = maxHeight / actualHeight;
            // actualWidth = (int) (imgRatio * actualWidth);
            // actualHeight = (int) maxHeight;
            //
            // }
            // else if (imgRatio > maxRatio)
            // {
            // imgRatio = maxWidth / actualWidth;
            // actualHeight = (int) (imgRatio * actualHeight);
            // actualWidth = (int) maxWidth;
            // }
            // else
            // {
            // actualHeight = (int) maxHeight;
            // actualWidth = (int) maxWidth;
            //
            // }
            // }

            // options.inSampleSize = utils.calculateInSampleSize(options, actualWidth, actualHeight);
            options.inSampleSize = imageScal;
            options.inJustDecodeBounds = false;
            options.inDither = true;
            options.inPurgeable = true;
            options.inInputShareable = true;
            options.inTempStorage = new byte[16 * 1024];

            try
            {
                bmp = BitmapFactory.decodeFile(filePath, options);
                bmp = decodeFile(filePath);
            }
            catch (OutOfMemoryError exception)
            {
                exception.printStackTrace();

            }
            boolean done = false;

            while (!done)
            {
                try
                {
                    scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888);

                    // scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888);

                    done = true;
                }
                catch (OutOfMemoryError exception)
                {
                    // 15923 × 1790
                    // 5616 × 3744
                    // 8150 × 9154
                    actualWidth = actualWidth - ((actualWidth * 2) / 100);
                    actualHeight = actualHeight - ((actualHeight * 2) / 100);
                    // scaledBitmap = Bitmap.createBitmap(5616, 3744, Bitmap.Config.ARGB_8888);
                    exception.printStackTrace();
                }

            }

            float ratioX = actualWidth / (float) options.outWidth;
            float ratioY = actualHeight / (float) options.outHeight;
            float middleX = actualWidth / 2.0f;
            float middleY = actualHeight / 2.0f;

            Matrix scaleMatrix = new Matrix();
            scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);

            Canvas canvas = new Canvas(scaledBitmap);
            canvas.setMatrix(scaleMatrix);
            canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));

            // Resize image stored in sdcard
            FileOutputStream out = null;
            // filename =AppConfig.fileTosaveMedia(context, FileType.IMAGE, true).getAbsolutePath();
            int compress = 50;
            try
            {
                do
                {
                    imgFile = AppConfig.fileTosaveMedia(context, FileType.IMAGE, true);
                    out = new FileOutputStream(imgFile);
                    scaledBitmap.compress(Bitmap.CompressFormat.JPEG, compress, out);

                    resizeImagePath = imgFile.getAbsolutePath();

                    // Thread.sleep(15000);
                    // imgFile = new File(filename);
                    bytes = imgFile.length();
                    kilobytes = (bytes / 1024);
                    megabytes = (kilobytes / 1024);
                    System.out.println("resized image size in mb:" + df.format(megabytes));

                    filesize = Double.parseDouble(df.format(megabytes));
                    if (filesize > 2.00f)
                    {
                        compress = 30;
                    }
                } while (filesize > 2.00f);
                scaledBitmap.recycle();
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }
        }
        else
        {

            FileOutputStream out = null;
            // FileInputStream in = null;
            imgFile = AppConfig.fileTosaveMedia(context, FileType.IMAGE, true);
            resizeImagePath = imgFile.getAbsolutePath();
            InputStream in = null;
            OutputStream outTemp = null;
            try
            {

                // create output directory if it doesn't exist

                in = new FileInputStream(filePath);
                outTemp = new FileOutputStream(resizeImagePath);

                byte[] buffer = new byte[1024];
                int read;
                while ((read = in.read(buffer)) != -1)
                {
                    outTemp.write(buffer, 0, read);
                }
                in.close();
                in = null;

                // write the output file (You have now copied the file)
                outTemp.flush();
                outTemp.close();
                outTemp = null;

            }
            catch (FileNotFoundException fnfe1)
            {
                Log.e("tag", fnfe1.getMessage());
            }
            catch (Exception e)
            {
                Log.e("tag", e.getMessage());
            }

            // try
            // {
            // Bitmap bmp = decodeFile(filePath);
            // // in = new FileInputStream(new File(imagePath));
            // // persistImage(bitmap, name);
            // out = new FileOutputStream(resizeImagePath);
            // bmp.compress(Bitmap.CompressFormat.JPEG, 100, out);
            // out.flush();
            // out.close();
            // // FileIO.copyStream(in, out);
            // }
            // catch (Exception e)
            // {
            // e.printStackTrace();
            // }
        }
        CustomLogHandler.printDebug(TAG, "resizeImagePath:" + resizeImagePath);
        return resizeImagePath;
    }

我在Google搜索和阅读博客上花了很多时间。然后在创建上述代码后,我找到了this

以上代码是否正确?或者是否有其他库用于压缩图像?

请帮帮我。

5 个答案:

答案 0 :(得分:24)

尝试以下代码: -

public String compressImage(String imageUri) {

        String filePath = getRealPathFromURI(imageUri);
        Bitmap scaledBitmap = null;

        BitmapFactory.Options options = new BitmapFactory.Options();

//      by setting this field as true, the actual bitmap pixels are not loaded in the memory. Just the bounds are loaded. If
//      you try the use the bitmap here, you will get null.
        options.inJustDecodeBounds = true;
        Bitmap bmp = BitmapFactory.decodeFile(filePath, options);

        int actualHeight = options.outHeight;
        int actualWidth = options.outWidth;

//      max Height and width values of the compressed image is taken as 816x612

        float maxHeight = 816.0f;
        float maxWidth = 612.0f;
        float imgRatio = actualWidth / actualHeight;
        float maxRatio = maxWidth / maxHeight;

//      width and height values are set maintaining the aspect ratio of the image

        if (actualHeight > maxHeight || actualWidth > maxWidth) {
            if (imgRatio < maxRatio) {               imgRatio = maxHeight / actualHeight;                actualWidth = (int) (imgRatio * actualWidth);               actualHeight = (int) maxHeight;             } else if (imgRatio > maxRatio) {
                imgRatio = maxWidth / actualWidth;
                actualHeight = (int) (imgRatio * actualHeight);
                actualWidth = (int) maxWidth;
            } else {
                actualHeight = (int) maxHeight;
                actualWidth = (int) maxWidth;

            }
        }

//      setting inSampleSize value allows to load a scaled down version of the original image

        options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);

//      inJustDecodeBounds set to false to load the actual bitmap
        options.inJustDecodeBounds = false;

//      this options allow android to claim the bitmap memory if it runs low on memory
        options.inPurgeable = true;
        options.inInputShareable = true;
        options.inTempStorage = new byte[16 * 1024];

        try {
//          load the bitmap from its path
            bmp = BitmapFactory.decodeFile(filePath, options);
        } catch (OutOfMemoryError exception) {
            exception.printStackTrace();

        }
        try {
            scaledBitmap = Bitmap.createBitmap(actualWidth, actualHeight,Bitmap.Config.ARGB_8888);
        } catch (OutOfMemoryError exception) {
            exception.printStackTrace();
        }

        float ratioX = actualWidth / (float) options.outWidth;
        float ratioY = actualHeight / (float) options.outHeight;
        float middleX = actualWidth / 2.0f;
        float middleY = actualHeight / 2.0f;

        Matrix scaleMatrix = new Matrix();
        scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);

        Canvas canvas = new Canvas(scaledBitmap);
        canvas.setMatrix(scaleMatrix);
        canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));

//      check the rotation of the image and display it properly
        ExifInterface exif;
        try {
            exif = new ExifInterface(filePath);

            int orientation = exif.getAttributeInt(
                    ExifInterface.TAG_ORIENTATION, 0);
            Log.d("EXIF", "Exif: " + orientation);
            Matrix matrix = new Matrix();
            if (orientation == 6) {
                matrix.postRotate(90);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 3) {
                matrix.postRotate(180);
                Log.d("EXIF", "Exif: " + orientation);
            } else if (orientation == 8) {
                matrix.postRotate(270);
                Log.d("EXIF", "Exif: " + orientation);
            }
            scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
                    scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix,
                    true);
        } catch (IOException e) {
            e.printStackTrace();
        }

        FileOutputStream out = null;
        String filename = getFilename();
        try {
            out = new FileOutputStream(filename);

//          write the compressed bitmap at the destination specified by filename.
            scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        return filename;

    }

有关信息,请参阅以下链接: -

http://voidcanvas.com/whatsapp-like-image-compression-in-android/

答案 1 :(得分:2)

希望帮助这个

  public static String compressImage(String filePath) {


    Bitmap scaledBitmap = null;

    BitmapFactory.Options options = new BitmapFactory.Options();



    options.inJustDecodeBounds = true;

    Bitmap bmp = BitmapFactory.decodeFile(filePath, options);

    int actualHeight = options.outHeight;

    int actualWidth = options.outWidth;


    float maxHeight = 400.0f;
    float maxWidth = 300.0f;

    float imgRatio = actualWidth / actualHeight;

    float maxRatio = maxWidth / maxHeight;



    if (actualHeight > maxHeight || actualWidth > maxWidth) 
    {

        if (imgRatio < maxRatio) { 

         imgRatio = maxHeight / actualHeight;

            actualWidth = (int) (imgRatio * actualWidth);   

        actualHeight = (int) maxHeight;    

    } else if (imgRatio > maxRatio) {

            imgRatio = maxWidth / actualWidth;

            actualHeight = (int) (imgRatio * actualHeight);

            actualWidth = (int) maxWidth;

        } else {

            actualHeight = (int) maxHeight;

            actualWidth = (int) maxWidth;

        }
    }



    options.inSampleSize = calculateInSampleSize(options, actualWidth,   
                             actualHeight);


   //      inJustDecodeBounds set to false to load the actual bitmap

    options.inJustDecodeBounds = false;


     //      this options allow android to claim the bitmap memory if it runs low on memory
    options.inPurgeable = true;

    options.inInputShareable = true;

    options.inTempStorage = new byte[16 * 1024];


    try {

    //          load the bitmap from its path

        bmp = BitmapFactory.decodeFile(filePath, options);

    } catch (OutOfMemoryError exception) {

        exception.printStackTrace();

    }
    try {

        scaledBitmap = Bitmap.createBitmap(actualWidth, 
                           actualHeight,Bitmap.Config.ARGB_8888);

    } catch (OutOfMemoryError exception) {

        exception.printStackTrace();
    }

    float ratioX = actualWidth / (float) options.outWidth;

    float ratioY = actualHeight / (float) options.outHeight;

    float middleX = actualWidth / 2.0f;

    float middleY = actualHeight / 2.0f;


    Matrix scaleMatrix = new Matrix();

    scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);



    Canvas canvas = new Canvas(scaledBitmap);

    canvas.setMatrix(scaleMatrix);

    canvas.drawBitmap(bmp, middleX - bmp.getWidth() / 2, middleY - bmp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));


    //      check the rotation of the image and display it properly

    ExifInterface exif;

    try {
        exif = new ExifInterface(filePath);

        int orientation = exif.getAttributeInt(
                ExifInterface.TAG_ORIENTATION, 0);

        Log.d("EXIF", "Exif: " + orientation);

        Matrix matrix = new Matrix();

        if (orientation == 6) {

            matrix.postRotate(90);

            Log.d("EXIF", "Exif: " + orientation);

        } else if (orientation == 3) {

            matrix.postRotate(180);

            Log.d("EXIF", "Exif: " + orientation);

        } else if (orientation == 8) {

            matrix.postRotate(270);

            Log.d("EXIF", "Exif: " + orientation);

        }
        scaledBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
                scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix,
                true);

    } catch (IOException e) {

        e.printStackTrace();
    }

    FileOutputStream out = null;

    String filename = getFilename();

    try {
        out = new FileOutputStream(filename);


        //          write the compressed bitmap at the destination specified by filename.
        scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);


    } catch (FileNotFoundException e) {

        e.printStackTrace();

    }

    return filename;

}

public static String getFilename() {
    File file = new File(Environment.getExternalStorageDirectory().getPath(), "Foldername/Images");

    if (!file.exists()) {
        file.mkdirs();
    }
    String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg");

    return uriSting;

}

public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {

    final int height = options.outHeight;

    final int width = options.outWidth;

    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int heightRatio = Math.round((float) height/ (float) 
reqHeight);

        final int widthRatio = Math.round((float) width / (float) reqWidth);

        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio; 

 }       final float totalPixels = width * height; 

 final float totalReqPixelsCap = reqWidth * reqHeight * 2;  

 while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
        inSampleSize++;
    }

    return inSampleSize;
}

public static Bitmap highlightImage(Bitmap src) {

      // create new bitmap, which will be painted and becomes result image

      Bitmap bmOut = Bitmap.createBitmap(src.getWidth() + 96, src.getHeight() + 96, Bitmap.Config.ARGB_8888);

      // setup canvas for painting

      Canvas canvas = new Canvas(bmOut);

      // setup default color

      canvas.drawColor(0, PorterDuff.Mode.CLEAR);

      // create a blur paint for capturing alpha

      Paint ptBlur = new Paint();

      ptBlur.setMaskFilter(new BlurMaskFilter(15, Blur.NORMAL));

      int[] offsetXY = new int[2];

      // capture alpha into a bitmap

      Bitmap bmAlpha = src.extractAlpha(ptBlur, offsetXY);

      // create a color paint
      Paint ptAlphaColor = new Paint();

      ptAlphaColor.setColor(0xFFFFFFFF);

      // paint color for captured alpha region (bitmap)

      canvas.drawBitmap(bmAlpha, offsetXY[0], offsetXY[1], ptAlphaColor);

      // free memory

      bmAlpha.recycle();

      // paint the image source
      canvas.drawBitmap(src, 0, 0, null);

      // return out final image
      return bmOut;
     }

答案 2 :(得分:1)

试试此代码

private void previewCapturedImage() {
    try {

        int targetW = 450;
        int targetH = 450;
        Log.e("Get w", "width" + targetW);
        Log.e("Get H", "height" + targetH);
        // Get the dimensions of the bitmap
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(filename, bmOptions);
        int photoW = bmOptions.outWidth;
        int photoH = bmOptions.outHeight;

        // Determine how much to scale down the image
        int scaleFactor = Math.min(photoW / targetW, photoH / targetH);

        // Decode the image file into a Bitmap sized to fill the View
        bmOptions.inJustDecodeBounds = false;
        bmOptions.inSampleSize = scaleFactor << 1;
        bmOptions.inPurgeable = true;
        Bitmap bitmap = BitmapFactory.decodeFile(filename, bmOptions);

        Matrix mtx = new Matrix();

        try {

            File imageFile = new File(filename);
            imageFile1 = imageFile;
            ExifInterface exif = new ExifInterface(
                    imageFile.getAbsolutePath());
            int orientation = exif.getAttributeInt(
                    ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_NORMAL);
            Log.e("Orintation", "  :-" + orientation);
            switch (orientation) {
            case ExifInterface.ORIENTATION_ROTATE_270:

                mtx.postRotate(270);
                rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), mtx, true);
                if (rotatedBMP != bitmap)
                    bitmap.recycle();
                imgPreview.setImageBitmap(rotatedBMP);
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:

                mtx.postRotate(180);
                rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), mtx, true);
                if (rotatedBMP != bitmap)
                    bitmap.recycle();
                imgPreview.setImageBitmap(rotatedBMP);
                break;
            case ExifInterface.ORIENTATION_ROTATE_90:

                mtx.postRotate(90);
                rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), mtx, true);
                if (rotatedBMP != bitmap)
                    bitmap.recycle();
                imgPreview.setImageBitmap(rotatedBMP);
                break;
            case ExifInterface.ORIENTATION_NORMAL:

                mtx.postRotate(0);
                rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), mtx, true);
                if (rotatedBMP != bitmap)
                    bitmap.recycle();
                imgPreview.setImageBitmap(rotatedBMP);
                break;
            default:
                mtx.postRotate(0);
                rotatedBMP = Bitmap.createBitmap(bitmap, 0, 0,
                        bitmap.getWidth(), bitmap.getHeight(), mtx, true);
                if (rotatedBMP != bitmap)
                    bitmap.recycle();
                imgPreview.setImageBitmap(rotatedBMP);
                // img_profilepic.setImageBitmap(BitmapFactory
                // .decodeFile(mCurrentPhotoPath));

            }
            double megabytes = 0;
            if (imageFile1.exists()) {

                double bytes = imageFile1.length();
                double kilobytes = (bytes / 1024);
                megabytes = (kilobytes / 1024);
                double gigabytes = (megabytes / 1024);
                double terabytes = (gigabytes / 1024);
                double petabytes = (terabytes / 1024);
                double exabytes = (petabytes / 1024);
                double zettabytes = (exabytes / 1024);
                double yottabytes = (zettabytes / 1024);
                Log.e("Image Size After in KB", "20th May:" + kilobytes);
                Log.e("Image Size After in MB", "20th May:" + megabytes);

            }
            int AfterSize = rotatedBMP.getRowBytes()
                    * rotatedBMP.getHeight();
            Log.e("After Compress Withd ",
                    "21st May ::" + rotatedBMP.getWidth());
            Log.e("After Compress Withd ",
                    "21st May ::" + rotatedBMP.getWidth());
            Log.i("RotateImage", "Exif orientation: " + orientation);
            tv_After.setText("After Width:" + rotatedBMP.getWidth()
                    + " :Height:" + rotatedBMP.getHeight() + ":in MB :"
                    + megabytes + " :Bitmap: " + AfterSize);
        } catch (Exception e) {
            e.printStackTrace();
        }

    } catch (NullPointerException e) {
        e.printStackTrace();
    }
}

也提出了这种方法。

public int calculateInSampleSize(BitmapFactory.Options options,
        int reqWidth, int reqHeight) {
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {
        final int heightRatio = Math.round((float) height
                / (float) reqHeight);
        final int widthRatio = Math.round((float) width / (float) reqWidth);
        inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }
    final float totalPixels = width * height;
    final float totalReqPixelsCap = reqWidth * reqHeight * 2;
    while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap)     {
        inSampleSize++;
    }
    Log.e("In Sample Size..", "19th May :-" + inSampleSize);
    return inSampleSize;
}

答案 3 :(得分:0)

我用的是最高答案... 提到的方法不起作用,由于从Uri获取文件路径存在一些问题,它在某些小米手机中返回空路径。 使用 getFilePath()代替 getRealPathFromURI() ...,并将参数从 compressImage(String imageUri)更改为 compressImage(Uri imageUri)

private static String getFilePath(Context context, Uri uri) {
    String selection = null;
    String[] selectionArgs = null;
    // Uri is different in versions after KITKAT (Android 4.4), we need to
    if (Build.VERSION.SDK_INT >= 19 && DocumentsContract.isDocumentUri(context.getApplicationContext(), uri)) {
        if (isExternalStorageDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            return Environment.getExternalStorageDirectory() + "/" + split[1];
        } else if (isDownloadsDocument(uri)) {
            final String id = DocumentsContract.getDocumentId(uri);
            uri = ContentUris.withAppendedId(
                    Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
        } else if (isMediaDocument(uri)) {
            final String docId = DocumentsContract.getDocumentId(uri);
            final String[] split = docId.split(":");
            final String type = split[0];
            if ("image".equals(type)) {
                uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
            } else if ("video".equals(type)) {
                uri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
            } else if ("audio".equals(type)) {
                uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
            }
            selection = "_id=?";
            selectionArgs = new String[]{
                    split[1]
            };
        }
    }
    if ("content".equalsIgnoreCase(uri.getScheme())) {
        String[] projection = {
                MediaStore.Images.Media.DATA
        };
        Cursor cursor = null;
        try {
            cursor = context.getContentResolver()
                    .query(uri, projection, selection, selectionArgs, null);
            int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
            if (cursor.moveToFirst()) {
                return cursor.getString(column_index);
            }
        } catch (Exception e) {
        }
    } else if ("file".equalsIgnoreCase(uri.getScheme())) {
        return uri.getPath();
    }
    return null;
}

private static boolean isExternalStorageDocument(Uri uri) {
    return "com.android.externalstorage.documents".equals(uri.getAuthority());
}

private static boolean isDownloadsDocument(Uri uri) {
    return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}

private static boolean isMediaDocument(Uri uri) {
    return "com.android.providers.media.documents".equals(uri.getAuthority());
}

答案 4 :(得分:0)

我不了解 WhatsApp,但是,我通过阅读源代码设法了解 Telegram 如何做到这一点,并且我在我的博客上写了一篇关于他们如何逐步做到这一点的文章,您可以在此处找到{ {3}}。