Question

所以我想在android中选择一个文件，选择后我想将字节读入字节数组。但是，当我尝试读取字节时，出现错误：java.io.FileNotFoundException: /document/1358 (No such file or directory)。这是我的代码：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    switch(requestCode) {
        case ACTIVITY_CHOOSE_FILE: {
            if (resultCode == RESULT_OK) {
                Uri uri = data.getData();
                String filePath = uri.getPath();
                File file = new File(filePath);
                int size = (int) file.length();
                byte[] bytes = new byte[size];

                try {
                    BufferedInputStream buf = new BufferedInputStream(new FileInputStream(file)); //error??
                    buf.read(bytes, 0, bytes.length);
                    buf.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

这是我打开意图的代码：

Intent chooseFile;
Intent intent;
chooseFile = new Intent(Intent.ACTION_GET_CONTENT);
chooseFile.setType("*/*");
intent = Intent.createChooser(chooseFile, "Choose a file");
startActivityForResult(intent, ACTIVITY_CHOOSE_FILE);

Answer 1

从onActivityResult获取uri，然后使用此util类获取文件的相对路径：

public class RealPathUtil {

public static String getRealPath(Context context, Uri fileUri) {
    String realPath;
    // SDK < API11
    if (Build.VERSION.SDK_INT < 11) {
        realPath = RealPathUtil.getRealPathFromURI_BelowAPI11(context, fileUri);
    }
    // SDK >= 11 && SDK < 19
    else if (Build.VERSION.SDK_INT < 19) {
        realPath = RealPathUtil.getRealPathFromURI_API11to18(context, fileUri);
    }
    // SDK > 19 (Android 4.4) and up
    else {
        realPath = RealPathUtil.getRealPathFromURI_API19(context, fileUri);
    }
    return realPath;
}


@SuppressLint("NewApi")
public static String getRealPathFromURI_API11to18(Context context, Uri contentUri) {
    String[] proj = {MediaStore.Images.Media.DATA};
    String result = null;

    CursorLoader cursorLoader = new CursorLoader(context, contentUri, proj, null, null, null);
    Cursor cursor = cursorLoader.loadInBackground();

    if (cursor != null) {
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        result = cursor.getString(column_index);
        cursor.close();
    }
    return result;
}

public static String getRealPathFromURI_BelowAPI11(Context context, Uri contentUri) {
    String[] proj = {MediaStore.Images.Media.DATA};
    Cursor cursor = context.getContentResolver().query(contentUri, proj, null, null, null);
    int column_index = 0;
    String result = "";
    if (cursor != null) {
        column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        result = cursor.getString(column_index);
        cursor.close();
        return result;
    }
    return result;
}

/**
 * Get a file path from a Uri. This will get the the path for Storage Access
 * Framework Documents, as well as the _data field for the MediaStore and
 * other file-based ContentProviders.
 *
 * @param context The context.
 * @param uri     The Uri to query.
 * @author paulburke
 */
@SuppressLint("NewApi")
public static String getRealPathFromURI_API19(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 = "_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());
}}

如果您得到的文件如下：

File file = new File(RealPathUtil.getRealPath(this, data.getData()));

您可以使用此方法获取字节数组：

private byte[] getDataFromFile(File file) {
    int size = (int) file.length();
    byte[] bytes = new byte[size];
    try {
        BufferedInputStream buf = new BufferedInputStream(new FileInputStream(file));
        buf.read(bytes, 0, bytes.length);
        buf.close();
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return bytes;
}

试图将其读入字节数组时，意图选择的文件路径为空

1 个答案: