【原创】Android 4.4前后版本读取图库图片方式的变化

Android 4.4前后版本读取图库图片方式的变化

 

本文讲述Android 4.4（KitKat）前后访问图库以及访问后通过图片路径读取图片的变化

 

Android 4.4（KitKat）以前：

访问图库（方法一）：

     /**
     * Access the gallery to pick up an image. 
     */
     private   void  startPickPhotoActivity() {
        Intent intent =  new  Intent(Intent. ACTION_GET_CONTENT );
        intent.setType( "image/*" ); // Or 'image/ jpeg '
        startActivityForResult(intent,  RESULT_PICK_PHOTO_NORMAL );
    }

访问图库（方法二）：

     /**
     * Access the gallery to pick up an image. 
     */
     private   void  startPickPhotoActivity() {
        Intent intent =  new  Intent(Intent. ACTION_GET_CONTENT );
        intent.setType( "image/*" ); // Or 'image/ jpeg '
        Intent wrapperIntent = Intent. createChooser (intent,  null );
        startActivityForResult(wrapperIntent,  RESULT_PICK_PHOTO_NORMAL );
     }

 

获取文件路径&读取图片：

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RESULT_PICK_PHOTO_NORMAL) {
            if (resultCode == RESULT_OK && data != null) {
                mFileName = DemoUtils.getDataColumn(getApplicationContext(),
                        data.getData(), null, null);
                mColorBitmap = DemoUtils.getBitmap(mFileName);

                mImage.setImageBitmap(mColorBitmap);
            }
        }
    }

    public static final Bitmap getBitmap(String fileName) {
        Bitmap bitmap = null;
        try {
            Options options = new Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeFile(fileName, options);
            options.inSampleSize = Math.max(1, (int) Math.ceil(Math.max(
                    (double) options.outWidth / 1024f,
                    (double) options.outHeight / 1024f)));
            options.inJustDecodeBounds = false;
            bitmap = BitmapFactory.decodeFile(fileName, options);
        } catch (OutOfMemoryError error) {
            error.printStackTrace();
        }

        return bitmap;
    }

    /**
     * Get the value of the data column for this Uri . This is useful for
     * MediaStore Uris , and other file - based ContentProviders.
     * 
     * @param context
     *            The context.
     * @param uri
     *            The Uri to query.
     * @param selection
     *            (Optional) Filter used in the query.
     * @param selectionArgs
     *            (Optional) Selection arguments used in the query.
     * @return The value of the _data column, which is typically a file path.
     */
    public static String getDataColumn(Context context, Uri uri,
            String selection, String[] selectionArgs) {
        Cursor cursor = null;
        final String column = MediaColumns.DATA;
        final String[] projection = { column };
        try {
            cursor = context.getContentResolver().query(uri, projection,
                    selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                final int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }

 

Android 4.4（KitKat）及以后：

访问图库（方法一）：同上方法一

访问图库（方法二）：同上方法二

访问图库（方法三）：

     /**
     * Access the gallery to pick up an image. 
     */
     @TargetApi (Build.VERSION_CODES. KITKAT )
     private   void  startPickPhotoActivity() {
        Intent intent =  new  Intent(Intent. ACTION_OPEN_DOCUMENT );
        intent.setType( "image/*" ); // Or 'image/ jpeg '
        startActivityForResult(intent,  RESULT_PICK_PHOTO_NORMAL );
    }

 

获取文件路径&读取图片：

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == RESULT_PICK_PHOTO_KITKAT) {
            if (resultCode == RESULT_OK && data != null) {
                mFileName = DemoUtils.getPath(getApplicationContext(),
                        data.getData());
                mColorBitmap = DemoUtils.getBitmap(mFileName);

                mImage.setImageBitmap(mColorBitmap);
            }
        }
    }

    @TargetApi(Build.VERSION_CODES.KITKAT)
    public static String getPath(final Context context, final Uri uri) {
        final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
        // DocumentProvider
        if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
            // ExternalStorageProvider
            if (isExternalStorageDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];
                if ("primary".equalsIgnoreCase(type)) {
                    return Environment.getExternalStorageDirectory() + "/"
                            + split[1];
                }
                // TODO handle non-primary volumes
            }
            // DownloadsProvider
            else if (isDownloadsDocument(uri)) {
                final String id = DocumentsContract.getDocumentId(uri);
                final Uri contentUri = ContentUris.withAppendedId(
                        Uri.parse("content://downloads/public_downloads"),
                        Long.valueOf(id));
                return getDataColumn(context, contentUri, null, null);
            }
            // MediaProvider
            else if (isMediaDocument(uri)) {
                final String docId = DocumentsContract.getDocumentId(uri);
                final String[] split = docId.split(":");
                final String type = split[0];
                Uri contentUri = null;
                if ("image".equals(type)) {
                    contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
                } else if ("video".equals(type)) {
                    contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
                } else if ("audio".equals(type)) {
                    contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
                }
                final String selection = MediaColumns._ID + "=?";
                final String[] selectionArgs = new String[] { split[1] };
                return getDataColumn(context, contentUri, selection,
                        selectionArgs);
            }
        }
        // MediaStore (and general)
        else if ("content".equalsIgnoreCase(uri.getScheme())) {
            // Return the remote address
            if (isGooglePhotosUri(uri))
                return uri.getLastPathSegment();
            return getDataColumn(context, uri, null, null);
        }
        // File
        else if ("file".equalsIgnoreCase(uri.getScheme())) {
            return uri.getPath();
        }
        return null;
    }

    /**
     * Get the value of the data column for this Uri . This is useful for
     * MediaStore Uris , and other file - based ContentProviders.
     * 
     * @param context
     *            The context.
     * @param uri
     *            The Uri to query.
     * @param selection
     *            (Optional) Filter used in the query.
     * @param selectionArgs
     *            (Optional) Selection arguments used in the query.
     * @return The value of the _data column, which is typically a file path.
     */
    public static String getDataColumn(Context context, Uri uri,
            String selection, String[] selectionArgs) {
        Cursor cursor = null;
        final String column = MediaColumns.DATA;
        final String[] projection = { column };
        try {
            cursor = context.getContentResolver().query(uri, projection,
                    selection, selectionArgs, null);
            if (cursor != null && cursor.moveToFirst()) {
                final int index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(index);
            }
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is ExternalStorageProvider.
     */
    public static boolean isExternalStorageDocument(Uri uri) {
        return "com.android.externalstorage.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is DownloadsProvider.
     */
    public static boolean isDownloadsDocument(Uri uri) {
        return "com.android.providers.downloads.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is MediaProvider.
     */
    public static boolean isMediaDocument(Uri uri) {
        return "com.android.providers.media.documents".equals(uri
                .getAuthority());
    }

    /**
     * @param uri
     *            The Uri to check.
     * @return Whether the Uri authority is Google Photos.
     */
    public static boolean isGooglePhotosUri(Uri uri) {
        return "com.google.android.apps.photos.content".equals(uri
                .getAuthority());
    }

 

为什么会不一样呢？

Android 4.4（含）开始，通过方式访问图库后，返回的Uri如下（访问“最近”）：

Uri is：         content://com.android.providers.media.documents/document/image%3A18838
Uri.getPath is ：/document/image:18838
对应的图片真实路径：/storage/emulated/0/Pictures/Screenshots/Screenshot_2014-09-22-21-40-53.png

不但如此，对于不同类型图库，返回的Uri形式并不相同（访问普通相册）：

Uri is：         content://media/external/images/media/18822
Uri.getPath is ：/external/images/media/18822
对应的图片真实路径：/storage/emulated/0/Download/20130224235013.jpg

而4.4之前返回的Uri只存在一种形式，如下：

Uri is：         content://media/external/images/media/14046
Uri.getPath is ：/external/images/media/14046
对应的图片真实路径：/storage/emulated/0/DCIM/Camera/20130224235013.jpg

 

因此，在Android 4.4或更高版本设备上，通过简单的getDataColumn(Context, Uri, null, null)进行图片数据库已经不能满足所有需求，因此在获取图片真实路径的时候需要根据不同类型区分对待。