使用 Uri 創建文件后文件為空 - Retrofit

Question

我正在嘗試使用 Uri 創建一個文件。 但是當檢查它是否為空時，發現它是空的。 下面是 Uri 存儲在變量“ filePath ”中的代碼。

@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
            filePath = data.getData();                
            try {
                bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(), filePath);
                imageView.setImageBitmap(bitmap);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

所以我創建了一個函數來使用改造庫將文件上傳到服務器。 單擊按鈕時調用該函數。 下面是代碼：

private void uploadFile(Uri fileUri) {

        String descriptionString = "hello";
        File file = new File(fileUri.getPath());

        if(file.exists())
        {
            Toast.makeText(MainActivity.this,file.getPath(),Toast.LENGTH_SHORT).show();
        }
        else
        {
           Toast.makeText(MainActivity.this,file.getName(),Toast.LENGTH_SHORT).show();
        }

        RequestBody requestFile =
                RequestBody.create(
                        MediaType.parse(getContentResolver().getType(fileUri)),
                        file
                );

        MultipartBody.Part image =
                MultipartBody.Part.createFormData("image", file.getName(), requestFile);

        Call<ImageResponse> call = RetrofitClient.getInstance().getApi().uploadImage(descriptionString,image);

        call.enqueue(new Callback<ImageResponse>() {
            @Override
            public void onResponse(Call<ImageResponse> call, Response<ImageResponse> response) {
                ImageResponse imageResponse = response.body();
                if (imageResponse.isError())
                {
                    Toast.makeText(MainActivity.this,imageResponse.getMessage(),Toast.LENGTH_SHORT).show();
                }
                else
                {
                    Toast.makeText(MainActivity.this,imageResponse.getMessage(),Toast.LENGTH_SHORT).show();
                }
            }

            @Override
            public void onFailure(Call<ImageResponse> call, Throwable t) {
                Toast.makeText(MainActivity.this, t.getMessage(),Toast.LENGTH_SHORT).show();
            }
        });
    }

所以我的請求失敗了，因為文件不存在。 可能是什么原因？ 我正在使用模擬器並添加了所有必需的權限。 我不知道為什么它不應該工作。 請幫我！ 我是改裝新手。

我的清單：

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

我要吐司的最終回應是：

文檔/圖像：31（沒有這樣的文件或目錄）

Answer 1

問題是，無論您在 Manifest 中指定權限，您都必須在 Android v6.0 的運行時檢查權限。 所以你所要做的就是在運行時檢查權限。

這是代碼。 使用以下代碼：

//Check Permissions on runtime
    public boolean checkPermissionREAD_EXTERNAL_STORAGE(
            final Context context) {
        int currentAPIVersion = Build.VERSION.SDK_INT;
        if (currentAPIVersion >= android.os.Build.VERSION_CODES.M) {
            if (ContextCompat.checkSelfPermission(context,
                    Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                if (ActivityCompat.shouldShowRequestPermissionRationale(
                        (Activity) context,
                        Manifest.permission.READ_EXTERNAL_STORAGE)) {
                    showDialog("External storage", context,
                            Manifest.permission.READ_EXTERNAL_STORAGE);

                } else {
                    ActivityCompat
                            .requestPermissions(
                                    (Activity) context,
                                    new String[] { Manifest.permission.READ_EXTERNAL_STORAGE },
                                    MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                }
                return false;
            } else {
                return true;
            }

        } else {
            return true;
        }
    }

    public void showDialog(final String msg, final Context context,
                           final String permission) {
        AlertDialog.Builder alertBuilder = new AlertDialog.Builder(context);
        alertBuilder.setCancelable(true);
        alertBuilder.setTitle("Permission necessary");
        alertBuilder.setMessage(msg + " permission is necessary");
        alertBuilder.setPositiveButton(android.R.string.yes,
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        ActivityCompat.requestPermissions((Activity) context,
                                new String[] { permission },
                                MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE);
                    }
                });
        AlertDialog alert = alertBuilder.create();
        alert.show();
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           String[] permissions, int[] grantResults) {
        switch (requestCode) {
            case MY_PERMISSIONS_REQUEST_READ_EXTERNAL_STORAGE:
                if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // do your stuff
                } else {
                    Toast.makeText(MainActivity.this, "GET_ACCOUNTS Denied",
                            Toast.LENGTH_SHORT).show();
                }
                break;
            default:
                super.onRequestPermissionsResult(requestCode, permissions,
                        grantResults);
        }
    }
    //End permission code

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
            try {
                if (checkPermissionREAD_EXTERNAL_STORAGE(this)) {
                    filePath=data.getData();
                    bitmap = MediaStore.Images.Media.getBitmap(getContentResolver(),filePath);
                    imageView.setImageBitmap(bitmap);
                }

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

    private void uploadFile(Uri fileUri) {

        String descriptionString = "hello";
        File file=FileUtils.getFile(getApplicationContext(),fileUri);

        RequestBody requestFile =
                RequestBody.create(
                        MediaType.parse(getContentResolver().getType(fileUri)),
                        file
                );

        MultipartBody.Part image =
                MultipartBody.Part.createFormData("image", file.getName(), requestFile);

        Call<ImageResponse> call = RetrofitClient.getInstance().getApi().uploadImage(descriptionString,image);

        call.enqueue(new Callback<ImageResponse>() {
            @Override
            public void onResponse(Call<ImageResponse> call, Response<ImageResponse> response) {
                ImageResponse imageResponse = response.body();
                if (imageResponse.isError())
                {
                    Toast.makeText(MainActivity.this,imageResponse.getMessage(),Toast.LENGTH_SHORT).show();
                }
                else
                {
                    Toast.makeText(MainActivity.this,imageResponse.getMessage(),Toast.LENGTH_SHORT).show();
                }
            }

            @Override
            public void onFailure(Call<ImageResponse> call, Throwable t) {
                Toast.makeText(MainActivity.this, t.getMessage(),Toast.LENGTH_SHORT).show();
            }
        });
    }

下面是 FileUtils 類：

public class FileUtils {

    //replace this with your authority
    public static final String AUTHORITY = "com.ianhanniballake.localstorage.documents";


    private FileUtils() {
    } //private constructor to enforce Singleton pattern

    /**
     * TAG for log messages.
     */
    static final String TAG = "FileUtils";
    private static final boolean DEBUG = false; // Set to true to enable logging


    /**
     * @return Whether the URI is a local one.
     */
    public static boolean isLocal(String url) {
        if (url != null && !url.startsWith("http://") && !url.startsWith("https://")) {
            return true;
        }
        return false;
    }


    public static boolean isLocalStorageDocument(Uri uri) {
        return AUTHORITY.equals(uri.getAuthority());
    }

    /**
     * @param uri The Uri to check.
     * @return Whether the Uri authority is ExternalStorageProvider.
     * @author paulburke
     */
    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.
     * @author paulburke
     */
    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.
     * @author paulburke
     */
    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());
    }

    /**
     * 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.
     * @author paulburke
     */
    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()) {
                if (DEBUG)
                    DatabaseUtils.dumpCursor(cursor);

                final int column_index = cursor.getColumnIndexOrThrow(column);
                return cursor.getString(column_index);
            }
        } finally {
            if (cursor != null)
                cursor.close();
        }
        return null;
    }

    /**
     * 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.<br>
     * <br>
     * Callers should check whether the path is local before assuming it
     * represents a local file.
     *
     * @param context The context.
     * @param uri     The Uri to query.
     * @author paulburke
     * @see #isLocal(String)
     * @see #getFile(Context, Uri)
     */
    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)) {
            // LocalStorageProvider
            if (isLocalStorageDocument(uri)) {
                // The path is the id
                return DocumentsContract.getDocumentId(uri);
            }
            // ExternalStorageProvider
            else 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;
    }

    /**
     * Convert Uri into File, if possible.
     *
     * @return file A local file that the Uri was pointing to, or null if the
     * Uri is unsupported or pointed to a remote resource.
     * @author paulburke
     * @see #getPath(Context, Uri)
     */
    public static File getFile(Context context, Uri uri) {
        if (uri != null) {
            String path = getPath(context, uri);
            if (path != null && isLocal(path)) {
                return new File(path);
            }
        }
        return null;
    }


}