Samples
To help you understand some fundamental Android APIs and coding practices, a variety of sample
code is available from the Android SDK Manager. Each version of the Android platform available
from the SDK Manager offers its own set of sample apps.
To download the samples:
The
You can easily create new Android projects with the downloaded samples, modify them if you'd like, and then run them on an emulator or device.
To download the samples:
- Launch the Android SDK Manager.
- On Windows, double-click the SDK Manager.exe file at the root of the Android SDK directory.
- On Mac or Linux, open a terminal to the
tools/directory in the Android SDK, then executeandroid sdk.
- Expand the list of packages for the latest Android platform.
- Select and download Samples for SDK.
<sdk>/samples/android-<version>/
<version> number corresponds to the platform's
API level.You can easily create new Android projects with the downloaded samples, modify them if you'd like, and then run them on an emulator or device.
http://stackoverflow.com/questions/10829371/sync-data-between-android-app-and-webserver
Sync data between Android App and webserver
I have developed a application in android that I wanna sync
data (such as db record, media) between it and a server. If you've seen
I have some question(imagine we want to sync DB records):
Evernote or similar Applications, you certainly understand my mean.I have some question(imagine we want to sync DB records):
- Every user has a part of server space for himself(such as
EvernoteorDropbox). Maybe user create new records by cellphone and create new records in server or anyway. How can I match these records together? If there are records with sane ID What algorithms do you suggest me? - Except JSON, Are there any way for send data between cellphone device and server?
- If SyncAdapter and ContentProvider can solve my problems, please explain exactly for me. (If you could offer some samples or tutorials to me OR Any advice or keywords to help broaden/guide my search would be appreciated as well).
First
you need to figure out(decide on) your communication protocol with the
server - hence - what data you can transfer and how. – hovanessyan May 31 at 7:48
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That is
Important for me, transfer SQLlite data. but I would know how transfer
other data. I don't understand your mean about protocol. please more
explain. – omid nazifi May 31 at 8:01
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I'll try to answer all your questions by addressing the larger question: How can I sync data between a webserver and an android app?
Syncing data between your webserver and an android app requires a couple of different components on your android device.
A ContentProvider defines a consistent interface to interact with your stored data. It could also allow other applications to interact with your data if you wanted. Behind your ContentProvider could be a Sqlite database, a Cache, or any arbitrary storage mechanism.
While I would certainly recommend using a ContentProvider with a Sqlite database you could certainly use any java based storage mechanism you wanted.
As for how you identify if the records are the same, typically you'll create items with a unique id which you store both on the android device and the server. You can use that to make sure you're referring to the same reference. Furthermore, you can store column attributes like "updated_at" to make sure that you're always getting the freshest data, or you don't accidentally write over newly written data.
Hope this helps.
Syncing data between your webserver and an android app requires a couple of different components on your android device.
Persistent Storage:
This is how your phone actually stores the data it receives from the webserver. One possible method for accomplishing this is writing your own custom ContentProvider backed by a Sqlite database. A decent tutorial for a content provider can be found here: http://thinkandroid.wordpress.com/2010/01/13/writing-your-own-contentprovider/A ContentProvider defines a consistent interface to interact with your stored data. It could also allow other applications to interact with your data if you wanted. Behind your ContentProvider could be a Sqlite database, a Cache, or any arbitrary storage mechanism.
While I would certainly recommend using a ContentProvider with a Sqlite database you could certainly use any java based storage mechanism you wanted.
Data Interchange Format:
This is the format you use to send the data between your webserver and your android app. The two most popular formats these days are XML and JSON. When choosing your format, you should think about what sort of serialization libraries are available. I know off-hand that there's a fantastic library for json serialization called gson: http://code.google.com/p/google-gson/, although I'm sure similar libraries exist for XML.Synchronization Service
You'll want some sort of asynchronous task which can get new data from your server and refresh the mobile content to reflect the content of the server. You'll also want to notify the server whenever you make local changes to content and want to reflect those changes. Android provides the SyncAdapter pattern as a way to easily solve this pattern. You'll need to register user accounts, and then Android will perform lots of magic for you, and allow you to automatically sync. Here's a good tutorial: http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-1/As for how you identify if the records are the same, typically you'll create items with a unique id which you store both on the android device and the server. You can use that to make sure you're referring to the same reference. Furthermore, you can store column attributes like "updated_at" to make sure that you're always getting the freshest data, or you don't accidentally write over newly written data.
Hope this helps.
http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-1/
Writing an Android Sync Provider: Part 1
One of the highlights of the Android 2.0 SDK is that you can write custom sync providers to integrate with the system contacts, calendars, etc. The only problem is that there’s very little documentation on how it all fits together. And worse, if you mess up in certain places, the Android system will crash and reboot! Always up for a challenge, I’ve navigated through the sparse documentation, vague mailing list posts, and the Android source code itself to build a sync provider for our Last.fm app. Want to know how to build your own? Read on!Account Authenticators
The first piece of the puzzle is called an Account Authenticator, which defines how the user’s account will appear in the “Accounts & Sync” settings. Implementing an Account Authenticator requires 3 pieces: a service that returns a subclass of AbstractAccountAuthenticator from the onBind method, an activity to prompt the user to enter their credentials, and an xml file describing how your account should look when displayed to the user. You’ll also need to add the android.permission.AUTHENTICATE_ACCOUNTS permission to your AndroidManifest.xml.The Service
The authenticator service is expected to return a subclass of AbstractAccountAuthenticator from the onBind method — if you don’t, Android will crash and reboot when you try to add a new account to the system. The only method in AbstractAccountAuthenticator we really need to implement is addAccount, which returns an Intent that the system will use to display the login dialog to the user. The implementation below will launch our app’s main launcher activity with an action of “fm.last.android.sync.LOGIN” and an extra containing the AccountAuthenticatorResponse object we use to pass data back to the system after the user has logged in.AccountAuthenticatorService.java
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import fm.last.android.LastFm;
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import android.accounts.AbstractAccountAuthenticator;
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import android.accounts.Account;
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import android.accounts.AccountAuthenticatorResponse;
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import android.accounts.AccountManager;
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import android.accounts.NetworkErrorException;
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import android.app.Service;
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import android.content.Context;
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import android.content.Intent;
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import android.os.Bundle;
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import android.os.IBinder;
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import android.util.Log;
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/**
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* Authenticator service that returns a subclass of AbstractAccountAuthenticator in onBind()
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*/
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public class AccountAuthenticatorService extends Service {
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private static final String TAG = "AccountAuthenticatorService";
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private static AccountAuthenticatorImpl sAccountAuthenticator = null;
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public AccountAuthenticatorService() {
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super();
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}
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public IBinder onBind(Intent intent) {
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IBinder ret = null;
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if (intent.getAction().equals(android.accounts.AccountManager.ACTION_AUTHENTICATOR_INTENT))
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ret = getAuthenticator().getIBinder();
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return ret;
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}
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private AccountAuthenticatorImpl getAuthenticator() {
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if (sAccountAuthenticator == null)
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sAccountAuthenticator = new AccountAuthenticatorImpl(this);
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return sAccountAuthenticator;
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}
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private static class AccountAuthenticatorImpl extends AbstractAccountAuthenticator {
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private Context mContext;
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public AccountAuthenticatorImpl(Context context) {
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super(context);
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mContext = context;
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}
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/*
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* The user has requested to add a new account to the system. We return an intent that will launch our login screen if the user has not logged in yet,
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* otherwise our activity will just pass the user's credentials on to the account manager.
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*/
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@Override
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public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options)
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throws NetworkErrorException {
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Bundle reply = new Bundle();
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Intent i = new Intent(mContext, LastFm.class);
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i.setAction("fm.last.android.sync.LOGIN");
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i.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response);
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reply.putParcelable(AccountManager.KEY_INTENT, i);
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return reply;
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}
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@Override
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public Bundle confirmCredentials(AccountAuthenticatorResponse response, Account account, Bundle options) {
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return null;
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}
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@Override
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public Bundle editProperties(AccountAuthenticatorResponse response, String accountType) {
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return null;
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}
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@Override
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public Bundle getAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) throws NetworkErrorException {
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return null;
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}
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@Override
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public String getAuthTokenLabel(String authTokenType) {
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return null;
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}
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@Override
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public Bundle hasFeatures(AccountAuthenticatorResponse response, Account account, String[] features) throws NetworkErrorException {
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return null;
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}
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@Override
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public Bundle updateCredentials(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options) {
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return null;
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}
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}
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}
Snippet from AndroidManifest.xml
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<service android:name="AccountAuthenticatorService"
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android:exported="true" android:process=":auth">
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<intent-filter>
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<action android:name="android.accounts.AccountAuthenticator" />
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</intent-filter>
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<meta-data android:name="android.accounts.AccountAuthenticator"
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android:resource="@xml/authenticator" />
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</service>
The Activity
If you don’t already have a login screen, there’s a convenience class AccountAuthenticatorActivity you can subclass that will pass your response back to the authentication manager for you, however if you already have a login activity in place you may find it easier to just pass the data back yourself, as I have done here. When the user has successfully been authenticated, we create an Account object for the user’s credentials. An account has an account name, such as the username or email address, and an account type, which you will define in your xml file next. You may find it easier to store your account type in strings.xml and use getString() to fetch it, as it is used in multiple places.Snippet from the Last.fm login activity
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Account account = new Account(username, getString(R.string.ACCOUNT_TYPE)));
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AccountManager am = AccountManager.get(this);
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boolean accountCreated = am.addAccountExplicitly(account, password, null);
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Bundle extras = getIntent.getExtras();
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if (extras != null) {
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if (accountCreated) { //Pass the new account back to the account manager
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AccountAuthenticatorResponse response = extras.getParcelable(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE);
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Bundle result = new Bundle();
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result.putString(AccountManager.KEY_ACCOUNT_NAME, username);
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result.putString(AccountManager.KEY_ACCOUNT_TYPE, getString(R.string.ACCOUNT_TYPE));
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response.onResult(result);
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}
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finish();
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}
The XML definition file
The account xml file defines what the user will see when they’re interacting with your account. It contains a user-readable name, the system account type you’re defining, various icons, and a reference to an xml file containing PreferenceScreens the user will see when modifying your account.authenticator.xml
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<account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"
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android:accountType="fm.last.android.account"
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android:icon="@drawable/icon"
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android:smallIcon="@drawable/icon"
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android:label="@string/app_name"
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android:accountPreferences="@xml/account_preferences"/>
account_preferences.xml
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<PreferenceScreen
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xmlns:android="http://schemas.android.com/apk/res/android">
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<PreferenceCategory
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android:title="General Settings" />
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<PreferenceScreen
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android:key="account_settings"
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android:title="Account Settings"
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android:summary="Sync frequency, notifications, etc.">
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<intent
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android:action="fm.last.android.activity.Preferences.ACCOUNT_SETUP"
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android:targetPackage="fm.last.android"
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android:targetClass="fm.last.android.activity.Preferences" />
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</PreferenceScreen>
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</PreferenceScreen>
Putting it all together
Now we’re ready for testing! The Android accounts setting screen doesn’t handle exceptions very well — if something goes wrong, your device will reboot! A better way to test is to launch the emulator, run the “Dev Tools” app, and pick “AccountsTester”.
You should see your new account type in the list, along with the built-in “Corporate” account type. Go ahead and select your account type from the drop-down list, and then press the “Add” button, and you should be presented with your login activity. After authenticating, your account should appear in a list below the buttons. At this point, it should be safe to use the system “Accounts & Sync” settings screen to remove or modify your account.
Ready to fill in that section below “Data & synchronization”? Let’s move on to part 2!
The source code for the implementation referenced here is available in my Last.fm github project under the terms of the GNU General Public License. A standalone sample project is also available here under the terms of the Apache License 2.0. Google has also released their own sample sync provider on the Android developer portal that’s a bit more complete than mine.
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