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Dropbox Java client for Android: how to refresh token?
My app just needs to upload a backup file to a dropbox account from mine, so the access must be off-line (no prompting to the user, that would be confusing). This is carried out when the user finishe...
Okay, solved.
I summarized the process in the following notes:
Dropbox client API
1Cloud backup with the Dropbox API
Until september 2022, it was possible to generate an access token, use it when creating the client, and don’t worry again about authorization. This is not possible anymore, so in order to create a backup system the most similar access system is PKCE for an offline app.
2Refresh token
After creating the app in the App Console, ignore the “generate token” option since this only creates a token valid for about 4 hours (though there is no note about this). Keep the PKCE activated.
Now, paste the following line in the address bar of your browser:
https://www.dropbox.com/oauth2/authorize?token_access_type=offline&response_type=code&client_id=<App key>
You need to substitute <App Key> for the application key that appears in the App Console. Keep the App Secret code near, as well.
You will authorize the app only once through that URL, and the answer will be the so called authorization code, an hexadecimal code. You need to take note of this code.
3Obtaining the refresh token
Now you have to open a terminal and paste there:
curl https://api.dropbox.com/oauth2/token -d code=<Authorization Code> -d grant_type=authorization_code -u <App key>:<App secret>You have to substitute <Authorization Code> with the last obtained token, <App Key> with the App Key and <App Secret> with the App Secret, these latter appearing in the App Console.
The answer will be a JSON piece of data similar to the following one:
{ "access_token":"sl...", "token_type": "bearer", "expires_in": 14400, "refresh_token": "oDfT54975DfGh12345KlMnOpQrSt01a", "scope": "account_info.read files.content.read ...", "uid": "123...", "account_id": "dbid:AB..." }The access token would be valid for the app to access Dropbox for 4 hours (expires_in). Note the “sl.” prefix (Short Lived). The important code here is refresh_token, which is a permanent token that you can access Dropbox with.
4Using the Java API
The problem with the API is that it is not always intuitive to use. With the PKCE access system, we only need to change the Dropbox client object in respect to what appears in the documentation.
final String APP_PACKAGE = OWNER.getPackageName(); final DbxRequestConfig CONFIG = DbxRequestConfig.newBuilder( APP_PACKAGE ).build(); final DbxCredential CREDENTIALS = new DbxCredential( "", 0L, <dropbox refresh token>, <app key>, <app secret> ); this.DBOX_CLIENT = new DbxClientV2( this.CONFIG, CREDENTIALS );The remaining code is left untouched.
Okay, solved.
I summarized the process in the following notes:
Dropbox client API
1Cloud backup with the Dropbox API
Until september 2022, it was possible to generate an access token, use it when creating the client, and don’t worry again about authorization. This is not possible anymore, so in order to create a backup system the most similar access system is PKCE for an offline app.
2Refresh token
After creating the app in the App Console, ignore the “generate token” option since this only creates a token valid for about 4 hours (though there is no note about this). Keep the PKCE activated.
Now, paste the following line in the address bar of your browser:
https://www.dropbox.com/oauth2/authorize?token_access_type=offline&response_type=code&client_id=<App key>
You need to substitute <App Key> for the application key that appears in the App Console. Keep the App Secret code near, as well.
You will authorize the app only once through that URL, and the answer will be the so called authorization code, an hexadecimal code. You need to take note of this code.
3Obtaining the refresh token
Now you have to open a terminal and paste there:
curl https://api.dropbox.com/oauth2/token -d code=<Authorization Code> -d grant_type=authorization_code -u <App key>:<App secret>
You have to substitute <Authorization Code> with the last obtained token, <App Key> with the App Key and <App Secret> with the App Secret, these latter appearing in the App Console.
The answer will be a JSON piece of data similar to the following one:
{
"access_token":"sl...",
"token_type": "bearer",
"expires_in": 14400,
"refresh_token": "oDfT54975DfGh12345KlMnOpQrSt01a",
"scope": "account_info.read files.content.read ...",
"uid": "123...",
"account_id": "dbid:AB..."
}
The access token would be valid for the app to access Dropbox for 4 hours (expires_in). Note the “sl.” prefix (Short Lived). The important code here is refresh_token, which is a permanent token that you can access Dropbox with.
4Using the Java API
The problem with the API is that it is not always intuitive to use. With the PKCE access system, we only need to change the Dropbox client object in respect to what appears in the documentation.
final String APP_PACKAGE = OWNER.getPackageName();
final DbxRequestConfig CONFIG = DbxRequestConfig.newBuilder( APP_PACKAGE ).build();
final DbxCredential CREDENTIALS = new DbxCredential(
"",
0L,
<dropbox refresh token>,
<app key>,
<app secret> );
this.DBOX_CLIENT = new DbxClientV2( this.CONFIG, CREDENTIALS );
The remaining code is left untouched.
I realize this post is a little old. My problem was I needed to actually get a refreshed access token because I am doing this in multi-platform Kotlin, and have to keep the backup part more generic than using the android JDK’s (7.0), that will not work on the IOS side. I spent a week or two trying to get it to actually get a new access token, and couldn't find the last step to make it work. I thought I would share in case others might need it. I added this method to DropboxOAuthUtil
from the example (https://github.com/dropbox/dropbox-sdk-java/blob/main/examples/android/src/main/java/com/dropbox/core/examples/android/internal/api/DropboxOAuthUtil.kt)
I call this refresh before performing the backup and restore in case the token expired.
// Dave Adding this
fun refreshToken(appKey: String, refreshToken: String, appSecret: String): String {
val requestConfig = DbxRequestConfig(dropboxAppConfig.clientIdentifier)
val dbCredential = DbxCredential("", 0L, refreshToken, appKey, appSecret )
dbCredential.refresh(requestConfig)
logMessage.logDebug(TAG, "refreshToken NEW?? dbCredential.accessToken=${dbCredential.accessToken}")
return dbCredential.accessToken
}
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