Android：如何保证文件上传到WCF服务？

Question

My app create a few files dynamically and keeps track of the files through an object. At some point the object is passed to an IntentService. The purpose of the IntentService is to

• Create a XML-file to contain data about the other files
• Add the XML-file and the other files to a ZIP-file
• Upload the ZIP-file to a WCF-service

The ZIP-file MUST be uploaded at some point. Things can happen; the WCF-service may be down and so on.

What options do I have in terms of guaranteeing that ZIP-file will be uploaded? My current plan is to save some info to a SQLite DB and check it every time the app is started and take it from there. Not sure that is a good idea or if there are better ways to handle this.

Also, I am an Android newbie, but if I have understood things correctly, if the IntentService is shut down before it is done, it will automatically be re-created with the same Intent and such at some point, right? Else I will have to take that into account as well.

Answer 1

You should take a look at using the built in sync service by making use of a sync adapter Have a look at this http://naked-code.blogspot.co.uk/2011/05/revenge-of-syncadapter-synchronizing.html

Watch the google I/O video embedded into that page.

You should take note that Virgil is suggesting that to use anything other than a sync adapter is just plain wrong. SyncAdapters are simple to implement and the link above also demonstrated how to set one up.

A SyncAdapter will take care of re-try attempts and will choose the optimal moment to sync data for your phone. You can schedule sync adapters or you can request an immediate sync, whatever suits your needs.

names and passwords are not saved by the account manager. They will; be needed by your website or an oauth2 service but the account manager stores the token not credcentials. If the token needs refreshing then the user is shown the account manager login screen and your code is then run to fetch a new auth token.

See http://developer.android.com/training/id-auth/identify.html for more details

Answer 2

My current plan is to save some info to a SQLite DB and check it every time the app is started and take it from there.

You're almost there. Instead of checking the DB every time the app starts, use an AlarmManager and check the status of the upload every X hours / days. The upload can be initiated by an IntentService .

The reason an AlarmManager is better is that the user may choose to keep the app open for days or weeks ! With a repeated alarm that runs your database and upload code, you can be certain that the upload attempt will happen at regular intervals.

Take a look at this related question on scheduling recurring tasks - Scheduling recurring task in Android