AccountManager.addAccount()
public AccountManagerFutureaddAccount(final String accountType, final String authTokenType, final String[] requiredFeatures, final Bundle addAccountOptions, final Activity activity, AccountManagerCallback callback, Handler handler) { ... }
在程序中创建指定类型的系统帐号，需要提供一个AccountManagerCallback类型的回调，后面会讲到其作用。
本方法要求用户添加指定类型的帐号。
此种帐号类型对应的authenticator将加载对应的UI来处理这个请求。 方法返回一个AccountManagerFuture对象，可解析出一个Bundle，包含以下信息： - KEY_ACCOUNT_NAME: 创建的帐号的名称 - KEY_ACCOUNT_TYPE: 帐号类型本方法创建一个匿名AmsTask实例并启动：
return new AmsTask(activity, handler, callback) { public void doWork() throws RemoteException { mService.addAcount(mResponse, accountType, authTokenType, requiredFeatures, activity != null, optionsIn); } }.start(); 这里，以异步的方式请求AccountManagerService.addAccount() start()方法立即返回，返回值是AccountManagerFuture类型的。
AccountManagerService.addAccount()
这个方法中，创建一个Session类型的匿名实例，并调用其bind()方法，最终捆绑到应用程序提供的authenticator service：
new Session(accounts, response, accountType, expectActivityLaunch, true /* stripAuthTokenFromResult */) { public void run() throws RemoteException { mAuthenticator.addAccount(this, mAccountType, authTokenType, requiredFeatures, options); } protected String toDebugString(long now) { return super.toDebugString(now) + ", addAccount" + ", accountType " + accountType + ", requiredFeatures " + (requiredFeatures != null ? TextUtils.join(",", requiredFeatures) : null); } }.bind(); 这是Session.bind()方法的相关细节：
void bind() { ... if (!bindToAuthenticator(mAccountType)) { Log.d(TAG, "bind attempt failed for " + toDebugString()); onError(AccountManager.ERROR_CODE_REMOTE_EXCEPTION, "bind failure"); } } bindToAuthenticator()方法找到对应的组件名称（应用程序中定义的相关service），并且对Service发起绑定：
private boolean bindToAuthenticator(String authenticatorType) { final AccountAuthenticatorCache.ServiceInfo authenticatorInfo; authenticatorInfo = mAuthenticatorCache.getServiceInfo( AuthenticatorDescription.newKey(authenticatorType), mAccounts.userId); ... Intent intent = new Intent(); intent.setAction(AccountManager.ACTION_AUTHENTICATOR_INTENT); intent.setComponent(authenticatorInfo.componentName); ... if (!mContext.bindService(intent, this, Context.BIND_AUTO_CREATE, mAccounts.userId)) { ... } return true; } Session类实现了ServiceConnection接口，因此，当成功绑定到对应的应用程序中的Service，其实现的onServiceConnected()方法将被调用：
public void onServiceConnected(ComponentName name, IBinder service) { mAuthenticator = IAccountAuthenticator.Stub.asInterface(service); try { run(); } catch (RemoteException e) { onError(AccountManager.ERROR_CODE_REMOTE_EXCEPTION, "remote exception"); } } 这里的service，即是AbstractAuthenticator抽象类提供的IBinder:
public abstract class AbstractAccountAuthenticator { ... private class Transport extends IAccountAuthenticator.Stub { public void addAccount(IAccountAuthenticatorResponse response, String accountType, String authTokenType, String[] features, Bundle options) throws RemoteException { ... try { final Bundle result = AbstractAccountAuthenticator.this.addAccount( new AccountAuthenticatorResponse(response), accountType, authTokenType, features, options); ... } ... } ... } ... private Transport mTransport = new Transport(); /** * @return the IBinder for the AccountAuthenticator */ public final IBinder getIBinder() { return mTransport.asBinder(); } ...} AbstractAccountAuthenticator的内部类Transport是IAccountAuthenticator接口的一个实现。后者规定了Authenticator的一组行为。 以添加帐号的操作为例，作为接口实现的Transport的addAccount()方法调用了AbstractAccountAuthenticator类的addAccount()抽象方法，这个方法的具体实现，则由应用程序中定义的authenticator子类来完成。 这里涉及到IPC，应用程序是服务端，提供服务的实现，而AccountManagerService则是客户端，负责通过代理对象发起调用。
Email的authenticator实现：
class PopImapAuthenticator extends AbstractAccountAuthenticator { ... @Override public Bundle addAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options) throws NetworkErrorException { // There are two cases here: // 1) We are called with a username/password; this comes from the traditional email // app UI; we simply create the account and return the proper bundle if (options != null && options.containsKey(OPTIONS_PASSWORD) && options.containsKey(OPTIONS_USERNAME)) { final Account account = new Account(options.getString(OPTIONS_USERNAME), AccountManagerTypes.TYPE_POP_IMAP); AccountManager.get(PopImapAuthenticatorService.this).addAccountExplicitly( account, options.getString(OPTIONS_PASSWORD), null); ... Bundle b = new Bundle(); b.putString(AccountManager.KEY_ACCOUNT_NAME, options.getString(OPTIONS_USERNAME)); b.putString(AccountManager.KEY_ACCOUNT_TYPE, AccountManagerTypes.TYPE_POP_IMAP); return b; // 2) The other case is that we're creating a new account from an Account manager // activity. In this case, we add an intent that will be used to gather the // account information... } else { Bundle b = new Bundle(); Intent intent = AccountSetupBasics.actionSetupPopImapIntent(PopImapAuthenticatorService.this); intent.putExtra(AccountManager.KEY_ACCOUNT_AUTHENTICATOR_RESPONSE, response); b.putParcelable(AccountManager.KEY_INTENT, intent); return b; } } 1) 如果是Email应用程序内部添加新的电子邮件帐号，此时已经取得了帐号的用户名和密码，那么直接创建对应的系统帐号，并调用AccountManager.addAccountExplicitly()将其添加到系统帐号数据库中，并返回帐号名称和类型。 2) 如果是从外部，比如系统设置中添加Email帐号，则创建指向Email应用中创建帐号对应的activity的Intent，并返回。这样，AmsTask实例在完成时会通过Handler机制调用AddAccountSettings活动提交的一个回调：
private AccountManagerCallback这样就会启动Email创建帐号的activity，之后又会走到1)中的步骤了。mCallback = new AccountManagerCallback () { public void run(AccountManagerFuture future) { boolean done = true; try { Bundle bundle = future.getResult(); //bundle.keySet(); Intent intent = (Intent) bundle.get(AccountManager.KEY_INTENT); if (intent != null) { done = false; Bundle addAccountOptions = new Bundle(); addAccountOptions.putParcelable(KEY_CALLER_IDENTITY, mPendingIntent); addAccountOptions.putBoolean(EXTRA_HAS_MULTIPLE_USERS, Utils.hasMultipleUsers(AddAccountSettings.this)); intent.putExtras(addAccountOptions); startActivityForResult(intent, ADD_ACCOUNT_REQUEST); ... }