Android ImageView不顯示從圖庫中拾取的圖像

Question

我正在嘗試從相機或圖庫中顯示圖像； 從相機imageview拍攝照片時顯示圖片，但從圖庫中選擇則不顯示圖片。 這是代碼。 我需要協助！ 注意，我向Manifest添加了權限，並且正在Android 6.0上進行測試。

完整的代碼在這里找到

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode != RESULT_OK) return;

        Bitmap bitmap   = null;
        String path     = "";

        if (requestCode == PICK_FROM_FILE) {
            mImageCaptureUri = data.getData();
            path = getRealPathFromURI(mImageCaptureUri); //from Gallery

            if (path == null)
                path = mImageCaptureUri.getPath(); //from File Manager

            if (path != null)
                bitmap  = BitmapFactory.decodeFile(path);
        } else {
            path    = mImageCaptureUri.getPath();
            bitmap  = BitmapFactory.decodeFile(path);
        }

        mImageView.setImageBitmap(bitmap);
    }

    public String getRealPathFromURI(Uri contentUri) {
        String [] proj      = {MediaStore.Images.Media.DATA};
        Cursor cursor       = managedQuery( contentUri, proj, null, null,null);

        if (cursor == null) return null;

        int column_index    = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);

        cursor.moveToFirst();

        return cursor.getString(column_index);
    }

Answer 1

刪除getRealPathFromURI() 。 如果Uri恰好來自MediaStore ，那么最多，即使僅在媒體可以訪問的地方，它才可能起作用。 如果Uri來自任何其他ContentProvider ，它將失敗；如果媒體位於可移動存儲中，則失敗。

使用圖像加載庫 （例如Picasso）將圖像從Uri加載到ImageView 。 無論如何，您都應該這樣做，因為您不應在主應用程序線程上進行磁盤I / O和圖像解碼，並且大多數圖像加載庫都將在后台線程上為您完成此工作。

如果您堅持要自己加載圖像，請使用ContentResolver和openInputStream()獲取Uri的InputStream 。 然后，使用BitmapFactory.decodeStream()從該InputStream獲取一個Bitmap 。

Answer 2

用這個

public static String getPath(final Context context, final Uri uri) {

    // check here to KITKAT or new version
    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];
            }
        }
        // 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 = "_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 = "_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());
}

然后使用以下代碼從具有所需寬度和高度的路徑獲取位圖圖像...

    // First decode with inJustDecodeBounds=true to check dimensions
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(path,options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    Bitmap img = BitmapFactory.decodeFile(path, options);