Reputation: 61
I want to design an Android file viewer for Google Drive.
At first, I implemented the app by using of the Google Android API, as follows,
private void retrieveNextPage(){
if(mHasMore == false)
return;
Query query = new Query.Builder().setPageToken(mNextPageToken).build();
com.google.android.gms.drive.Drive.DriveApi.query(getGoogleApiClient(), query).setResultCallback(metadataBufferResultResultCallback);
}
However, the Android Drive API only allows the app to view and fetch the files that created by itself. I cannot access other files on the drive through the app.
Therefore, I turned to another option, directly manipulate the Java Drive API.
According to the example on developer guide for Java,
https://developers.google.com/drive/web/quickstart/quickstart-java
The users have to manually copy and paste the "Authorization Code" between the browser and app, which is not a practical way to acquire the Access Token in Android.
To come out a new way, I used the GoogleAuthUtil
in Android API to acquire the Access Token, coincided with the GoogleCredential
and Drive
in Java API to fetch the file list, as follows,
private static List<File> retrieveFiles(Drive service) throws IOException{
List<File> result = new ArrayList<File>();
Files.List request = service.files().list();
do {
try{
FileList fileList = request.execute();
result.addAll(fileList.getItems());
request.setPageToken(fileList.getNextPageToken());
}catch (IOException e){
Log.d(dbgT + "JavaRetrieveFiles", "Retrieved Failed");
request.setPageToken(null);
}
}while (request.getPageToken() != null && request.getPageToken().length() > 0);
return result;
}
private class RetrieveTokenTask extends AsyncTask<String, Void, String>{
@Override
protected String doInBackground(String... params){
String accountName = params[0];
String scopes = "oauth2:" + "https://www.googleapis.com/auth/drive";
String token = null;
try{
token = GoogleAuthUtil.getToken(getApplicationContext(), accountName, scopes);
}
catch (IOException e){
Log.e(excpTAG, "IO Exception: " + e.getMessage());
}
catch (UserRecoverableAuthException e){
startActivityForResult(e.getIntent(), REQ_SIGN_IN_REQUIRED);
}
catch (GoogleAuthException e)
{
Log.e(excpTAG, "GoogleAuthException: " + e.getMessage());
}
return token;
}
@Override
protected void onPostExecute(String s){
super.onPostExecute(s);
//Get Access Token
Log.d( dbgT + "Token", s);
EditText tokenText = (EditText) findViewById(R.id.tokenText);
tokenText.setText(s);
EditText fileNameText = (EditText) findViewById(R.id.editTextMeta);
GoogleCredential credential = new GoogleCredential().setAccessToken(s);
HttpTransport httpTransport = new NetHttpTransport();
JsonFactory jsonFactory = new JacksonFactory();
Drive service = new Drive.Builder(httpTransport, jsonFactory, null).setHttpRequestInitializer(credential).build();
List<File> fileList;
try{
fileList = retrieveFiles(service);
for(int i=0; i< fileList.size(); i++)
fileNameText.append(fileList.get(i).getTitle());
}catch(IOException e){
Log.d(dbgT + "RetrieveFileList", "IO Exception" );
}
}
}
Unfortunately, the app always crashes by the causing of NetworkOnMainThreadException when request.execute()
in retrieveFiles
is invoked.
I checked my access token s
, it is usually in form of ya29.xxx...etc.
, and it can also be passed to my other .NET program for retrieving files from Google Drive. Therefore I can certain the access token is correct.
So my question is, how to create a correct GoogleCredential by using of access token, instead of applying authorization code in setFromTokenResponse
?
Thanks in advance.
Upvotes: 3
Views: 1379
Reputation: 61
Many thanks for Andy's tips, this problem is simply caused by the network operations occurs on the main thread, which is a very basic newbie error.
The Drive
in Google Drive SDK for Java, using network libraries without any background/thread worker, and now it is functional after I put the retrieveFiles()
into background.
Applying the GoogleAuthUtil
in Google Play Android SDK to acquire the access token, and followed by GoogleCredential
+Drive
in Java SDK that use the token to do the file operation in Google Drive.
This is a right way to avoid the scope restriction in Android SDK for Google Drive, allowing the developers to acquire the full permissive of accessing Google Drive.
Upvotes: 1