装过Android版的Facebook、lastfm的同学是否对于这些应用的功能感到惊喜,它们可以定期更新朋友的最新信息,将最新近况和心情短语集成入联系人中。这些应用全部是以Android2.0后的账户和同步机制为基础的。Google的例程中给出了名为SampleSyncAdpater的例子,通过分析该例子可以学会Android中的Account验证、同步Adapter的使用。
详细例子代码可以看sdk samples中提供的源码,现在拿2.2中的版本来简要说明。
首先是 class Authenticator extends AbstractAccountAuthenticator ,该类是账户认证类,打开手机的Setting里,有Account&Sync 一项,Authenticator就是实现其中的账号功能的类。
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- public Bundle addAccount(AccountAuthenticatorResponse response,
- String accountType, String authTokenType, String[] requiredFeatures,
- Bundle options) {
- final Intent intent = new Intent(mContext, AuthenticatorActivity.class);
- intent.putExtra(AuthenticatorActivity.PARAM_AUTHTOKEN_TYPE,
- authTokenType);
- intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE,
- response);
- final Bundle bundle = new Bundle();
- bundle.putParcelable(AccountManager.KEY_INTENT, intent);
- return bundle;
- }
其中addAccount方法用来定义需要增加账号时的操作,如调用AuthenticatorActivity来进行账号的添加认证。
在AuthenticatorActivity.java中定义了handleLogin(),此方法由login_activity.xml中的android:onClick="handleLogin"定义与ui中的okbutton的关联。
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- <Button
- android:id="@+id/ok_button"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content"
- android:layout_gravity="center_horizontal"
- android:minWidth="100dip"
- android:text="@string/login_activity_ok_button"
- android:onClick="handleLogin" />
handleLogin()将ui中的用户名和密码取得,并创建一个试图认证的线程,通过网络去服务端验证。
NetworkUtilities.java中的 public static boolean authenticate(String username, String password, Handler handler, final Context context)方法展示了通过网络验证的具体流程。得到服务端验证结果后,在sendResult()中通过handler.post调用来实现onAuthenticationResult()在AuthenticatorActivity中的运行。onAuthenticationResult()判断验证通过则结束AuthenticatorActivity,否则报出用户名密码错,让用户在AuthenticatorActivity中再次尝试验证。
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- public void handleLogin(View view) {
- if (mRequestNewAccount) {
- mUsername = mUsernameEdit.getText().toString();
- }
- mPassword = mPasswordEdit.getText().toString();
- if (TextUtils.isEmpty(mUsername) || TextUtils.isEmpty(mPassword)) {
- mMessage.setText(getMessage());
- } else {
- showProgress();
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- mAuthThread =
- NetworkUtilities.attemptAuth(mUsername, mPassword, mHandler,
- AuthenticatorActivity.this);
- }
- }
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- public static boolean authenticate(String username, String password,
- Handler handler, final Context context) {
- final HttpResponse resp;
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- final ArrayList<NameValuePair> params = new ArrayList<NameValuePair>();
- params.add(new BasicNameValuePair(PARAM_USERNAME, username));
- params.add(new BasicNameValuePair(PARAM_PASSWORD, password));
- HttpEntity entity = null;
- try {
- entity = new UrlEncodedFormEntity(params);
- } catch (final UnsupportedEncodingException e) {
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- throw new AssertionError(e);
- }
- final HttpPost post = new HttpPost(AUTH_URI);
- post.addHeader(entity.getContentType());
- post.setEntity(entity);
- maybeCreateHttpClient();
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- try {
- resp = mHttpClient.execute(post);
- if (resp.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
- if (Log.isLoggable(TAG, Log.VERBOSE)) {
- Log.v(TAG, "Successful authentication");
- }
- sendResult(true, handler, context);
- return true;
- } else {
- if (Log.isLoggable(TAG, Log.VERBOSE)) {
- Log.v(TAG, "Error authenticating" + resp.getStatusLine());
- }
- sendResult(false, handler, context);
- return false;
- }
- } catch (final IOException e) {
- if (Log.isLoggable(TAG, Log.VERBOSE)) {
- Log.v(TAG, "IOException when getting authtoken", e);
- }
- sendResult(false, handler, context);
- return false;
- } finally {
- if (Log.isLoggable(TAG, Log.VERBOSE)) {
- Log.v(TAG, "getAuthtoken completing");
- }
- }
- }
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- private static void sendResult(final Boolean result, final Handler handler,
- final Context context) {
- if (handler == null || context == null) {
- return;
- }
- handler.post(new Runnable() {
- public void run() {
- ((AuthenticatorActivity) context).onAuthenticationResult(result);
- }
- });
- }
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- public void onAuthenticationResult(boolean result) {
- Log.i(TAG, "onAuthenticationResult(" + result + ")");
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- hideProgress();
- if (result) {
- if (!mConfirmCredentials) {
- finishLogin();
- } else {
- finishConfirmCredentials(true);
- }
- } else {
- Log.e(TAG, "onAuthenticationResult: failed to authenticate");
- if (mRequestNewAccount) {
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- mMessage
- .setText(getText(R.string.login_activity_loginfail_text_both));
- } else {
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- mMessage
- .setText(getText(R.string.login_activity_loginfail_text_pwonly));
- }
- }
- }
Account的验证完毕后,就生成了账号,可以开始使用同步功能了。同步的主要逻辑在public class SyncAdapter extends AbstractThreadedSyncAdapter中实现。
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- @Override
- public void onPerformSync(Account account, Bundle extras, String authority,
- ContentProviderClient provider, SyncResult syncResult) {
- List<User> users;
- List<Status> statuses;
- String authtoken = null;
- try {
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- authtoken =
- mAccountManager.blockingGetAuthToken(account,
- Constants.AUTHTOKEN_TYPE, true );
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- users =
- NetworkUtilities.fetchFriendUpdates(account, authtoken,
- mLastUpdated);
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- mLastUpdated = new Date();
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- Log.d(TAG, "Calling contactManager's sync contacts");
- ContactManager.syncContacts(mContext, account.name, users);
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- statuses = NetworkUtilities.fetchFriendStatuses(account, authtoken);
- ContactManager.insertStatuses(mContext, account.name, statuses);
- } catch (final AuthenticatorException e) {
- syncResult.stats.numParseExceptions++;
- Log.e(TAG, "AuthenticatorException", e);
- } catch (final OperationCanceledException e) {
- Log.e(TAG, "OperationCanceledExcetpion", e);
- } catch (final IOException e) {
- Log.e(TAG, "IOException", e);
- syncResult.stats.numIoExceptions++;
- } catch (final AuthenticationException e) {
- mAccountManager.invalidateAuthToken(Constants.ACCOUNT_TYPE,
- authtoken);
- syncResult.stats.numAuthExceptions++;
- Log.e(TAG, "AuthenticationException", e);
- } catch (final ParseException e) {
- syncResult.stats.numParseExceptions++;
- Log.e(TAG, "ParseException", e);
- } catch (final JSONException e) {
- syncResult.stats.numParseExceptions++;
- Log.e(TAG, "JSONException", e);
- }
- }
onPerformSync中的执行流程中,使用NetworkUtilities中的fetchFriendUpdates和fetchFriendStatuses来访问服务端的联系人更新,并使用了例程中自己封装的ContactManager来读取、更新联系人信息。
那Account和SyncAdapter及其Service和xml定义之间是如何关联的呢? AndroidManifest.xml中定义了AccountAuthenticator,SyncAdapter及对应的Service和xml定义的关联。
- <application
- android:icon="@drawable/icon"
- android:label="@string/label">
- <!-- The authenticator service -->
- <service
- android:name=".authenticator.AuthenticationService"
- android:exported="true">
- <intent-filter>
- <action
- android:name="android.accounts.AccountAuthenticator" />
- </intent-filter>
- <meta-data
- android:name="android.accounts.AccountAuthenticator"
- android:resource="@xml/authenticator" />
- </service>
- <service
- android:name=".syncadapter.SyncService"
- android:exported="true">
- <intent-filter>
- <action
- android:name="android.content.SyncAdapter" />
- </intent-filter>
- <meta-data
- android:name="android.content.SyncAdapter"
- android:resource="@xml/syncadapter" />
- <meta-data
- android:name="android.provider.CONTACTS_STRUCTURE"
- android:resource="@xml/contacts" />
- </service>
- <activity
- android:name=".authenticator.AuthenticatorActivity"
- android:label="@string/ui_activity_title"
- android:theme="@android:style/Theme.Dialog"
- android:excludeFromRecents="true"
- >
- <!--
- No intent-filter here! This activity is only ever launched by
- someone who explicitly knows the class name
- -->
- </activity>
- </application>
更详细的代码细节和执行流程,可以去把SDK中的SampleSyncAdapter代码运行起来体会一下,不过要实现整个流程,必须搭建联系人的服务器端,例程中在目录samplesyncadapter_server中也提供了简单的server端python代码,需要搭建在google app engine上。搭建过程遇到一些问题,由于对python不熟我弄了几天才解决好搭建成功,其中遇到的一个model moudle找不到的问题需要你在model中新建一个__init__.py的空文件,来说明是一个python模块,如果你也遇到此问题,希望对你有帮助。