如何在Google Drive中替换文件？

Question

使用以下代码，该代码来自android-quickstart，如果您拍摄多张照片，则此代码可以生成具有相同名称的多个文件。如何修改以确保替换具有相同名称的文件？

public class MainActivity extends Activity implements ConnectionCallbacks,
        OnConnectionFailedListener {

    private static final String TAG = "android-drive-quickstart";
    private static final int REQUEST_CODE_CAPTURE_IMAGE = 1;
    private static final int REQUEST_CODE_CREATOR = 2;
    private static final int REQUEST_CODE_RESOLUTION = 3;

    private GoogleApiClient mGoogleApiClient;
    private Bitmap mBitmapToSave;

    /**
     * Create a new file and save it to Drive.
     */
    private void saveFileToDrive() {
        // Start by creating a new contents, and setting a callback.
        Log.i(TAG, "Creating new contents.");
        final Bitmap image = mBitmapToSave;
        Drive.DriveApi.newContents(mGoogleApiClient).setResultCallback(new ResultCallback<ContentsResult>() {

            @Override
            public void onResult(ContentsResult result) {
                // If the operation was not successful, we cannot do anything
                // and must
                // fail.
                if (!result.getStatus().isSuccess()) {
                    Log.i(TAG, "Failed to create new contents.");
                    return;
                }
                // Otherwise, we can write our data to the new contents.
                Log.i(TAG, "New contents created.");
                // Get an output stream for the contents.
                OutputStream outputStream = result.getContents().getOutputStream();
                // Write the bitmap data from it.
                ByteArrayOutputStream bitmapStream = new ByteArrayOutputStream();
                image.compress(Bitmap.CompressFormat.PNG, 100, bitmapStream);
                try {
                    outputStream.write(bitmapStream.toByteArray());
                } catch (IOException e1) {
                    Log.i(TAG, "Unable to write file contents.");
                }
                // Create the initial metadata - MIME type and title.
                // Note that the user will be able to change the title later.
                MetadataChangeSet metadataChangeSet = new MetadataChangeSet.Builder()
                        .setMimeType("image/jpeg")
                        .setTitle("Android Photo.png")
                        .build();
                // Create an intent for the file chooser, and start it.
                IntentSender intentSender = Drive.DriveApi
                        .newCreateFileActivityBuilder()
                        .setInitialMetadata(metadataChangeSet)
                        .setInitialContents(result.getContents())
                        .build(mGoogleApiClient);
                try {
                    startIntentSenderForResult(
                            intentSender, REQUEST_CODE_CREATOR, null, 0, 0, 0);
                } catch (SendIntentException e) {
                    Log.i(TAG, "Failed to launch file chooser.");
                }
            }
        });
    }

    @Override
    protected void onResume() {
        super.onResume();
        if (mGoogleApiClient == null) {
            // Create the API client and bind it to an instance variable.
            // We use this instance as the callback for connection and connection
            // failures.
            // Since no account name is passed, the user is prompted to choose.
            mGoogleApiClient = new GoogleApiClient.Builder(this)
                    .addApi(Drive.API)
                    .addScope(Drive.SCOPE_FILE)
                    .addConnectionCallbacks(this)
                    .addOnConnectionFailedListener(this)
                    .build();
        }
        // Connect the client. Once connected, the camera is launched.
        mGoogleApiClient.connect();
    }
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(Drive.API)
                .addScope(Drive.SCOPE_FILE)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();
    }
    @Override
    protected void onStart() {
        super.onStart();
        mGoogleApiClient.connect();
    }
    @Override
    protected void onPause() {
        if (mGoogleApiClient != null) {
            mGoogleApiClient.disconnect();
        }
        super.onPause();
    }

    @Override
    protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
        switch (requestCode) {
            case REQUEST_CODE_CAPTURE_IMAGE:
                // Called after a photo has been taken.
                if (resultCode == Activity.RESULT_OK) {
                    // Store the image data as a bitmap for writing later.
                    mBitmapToSave = (Bitmap) data.getExtras().get("data");
                }
                break;
            case REQUEST_CODE_CREATOR:
                // Called after a file is saved to Drive.
                if (resultCode == RESULT_OK) {
                    Log.i(TAG, "Image successfully saved.");
                    mBitmapToSave = null;
                    // Just start the camera again for another photo.
                    startActivityForResult(new Intent(MediaStore.ACTION_IMAGE_CAPTURE),
                            REQUEST_CODE_CAPTURE_IMAGE);
                }
                break;
        }
    }

    @Override
    public void onConnectionFailed(ConnectionResult result) {
        // Called whenever the API client fails to connect.
        Log.i(TAG, "GoogleApiClient connection failed: " + result.toString());
        if (!result.hasResolution()) {
            // show the localized error dialog.
            GooglePlayServicesUtil.getErrorDialog(result.getErrorCode(), this, 0).show();
            return;
        }
        // The failure has a resolution. Resolve it.
        // Called typically when the app is not yet authorized, and an
        // authorization
        // dialog is displayed to the user.
        try {
            result.startResolutionForResult(this, REQUEST_CODE_RESOLUTION);
        } catch (SendIntentException e) {
            Log.e(TAG, "Exception while starting resolution activity", e);
        }
    }

    @Override
    public void onConnected(Bundle connectionHint) {
        Log.i(TAG, "API client connected.");
        if (mBitmapToSave == null) {
            // This activity has no UI of its own. Just start the camera.
            startActivityForResult(new Intent(MediaStore.ACTION_IMAGE_CAPTURE),
                    REQUEST_CODE_CAPTURE_IMAGE);
            return;
        }
        saveFileToDrive();
    }

    @Override
    public void onConnectionSuspended(int cause) {
        Log.i(TAG, "GoogleApiClient connection suspended");
    }
}

- Yarh

---

我现在正在处理这个问题（使用另一个平台），但是如果你想替换文件，似乎需要先获取你要上传的文件的ID，从谷歌云盘中删除该文件，然后再上传文件。我知道这听起来很奇怪，但是谷歌云盘好像是根据它们独特的文件ID而不是文件名来检索文件的。因此，我编写了一个程序来返回所需文件/文件夹的ID。此外，请记住，文件夹和文件名称区分大小写。 - bvstone

@bvstone 我按照您描述的方式解决了那个问题，问题在于当时的 Android Drive API 不支持删除操作，因此我使用了 Java Drive API。 - Yarh

Answer 1

我们可以使用Google Drive API来实现以下功能：
- 查找现有文件
- 获取其ID
- 删除文件
- 写入新文件

- Yarh

---

我正在使用Android Drive API。我能够使用元数据获取drive_Id，但无法删除旧文件。你能分享删除文件的代码吗？ - megha

如果您希望文件保持相同的Google Drive共享链接，该怎么办？ - Red Knight

Answer 2

我按以下方式打开驱动器文件以进行写入：

writeDriveFile(DriveFile file, Handler handler){
    //see query task below to get a drive file by its name. Be careful you can get multiple data elements in the MetadataBuffer below if you have uploaded multiple files with the same name.
    Task<DriveContents> openFileTask = myDriveResourceClient.openFile(file, DriveFile.MODE_WRITE_ONLY);

然后使用该任务将一些对象字节写入流中someObject.getBytes()，这里没有任何魔法。然后提交结果。

openFileTask
            .continueWithTask(task -> {
                DriveContents contents = task.getResult();

                // Process contents...
                try (OutputStream writer = contents.getOutputStream()) {
                    writer.write(someObject.getBytes());
                    writer.close();
                }

                //Add whatever metadata you want here
                MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                        .setLastViewedByMeDate(new Date())
                        .build();

                //commit the file to Google Drive
                Task<Void> commitTask = myDriveResourceClient.commitContents(contents, changeSet);
                handler.onWriteResults();
                return commitTask;
            })
            .addOnFailureListener(e -> {
                // Handle failure
                Log.e(TAG, "Unable to read contents", e);
                handler.onDriveError(e);
            });

handler 是我定义的一个接口，用于处理 Drive API 执行后的错误或结果。你也可以添加 addOnCompleteListener() 来在写入完成后处理一些东西。 file 是通过查询任务获取的 DriveFile 实例。任务代码块中得到的元数据有一个 getDriveId() 方法，该方法有一个 asDriveFile() 方法可获取上面所需的 Drive 文件。

Query query = new Query.Builder()
            .addFilter(Filters.eq(SearchableField.TITLE, "file name"))
            .build();
Task<MetadataBuffer> queryTask = mDriveResourceClient.query(query);

然后处理 MetadataBuffer。

queryTask.continueWithTask(
                    task -> {
                        MetadataBuffer metadataBuffer = task.getResult() ;
                        //I have this loop because I wanted to know if there were other versions of the file on the drive
                        for(Metadata data : metadataBuffer) {
                            Log.d(TAG, "******************* metadataBuffer title is " + data.getTitle());

                            if(data.getTitle().equals("file name")){
                                //this is just a method I defined that encapsulates the drive writing code above.
                                writeDriveFile(data.getDriveId().asDriveFile(), jsonContent, handler);
                            }
                        }
                        return task;
                    })
            .addOnCompleteListener(task -> {
                //some complete tasks
                }
            })
            .addOnFailureListener(e -> {
                Log.e(TAG, "************************** Error searching for " + fileName, e);
                handler.onDriveError(e);
            });

这段代码是为了写入应用程序文件夹，但在创建资源客户端时只需设置正确的范围即可。

删除驱动器文件可以按以下方式完成。

 public void deleteDriveFile(DriveResource file){
    Task<Void> deleteTask = mDriveResourceClient.delete(file);
    deleteTask
            .continueWith(task -> {
                Log.d(TAG, "************* Deleted drive file: " + file.getDriveId().toInvariantString());
                return task;
            })
            .addOnFailureListener(e -> {
                //log some sort of error for yourself
            });
}

- musterjunk