AbstractAccountAuthenticator简介

本文翻译整理自： http://developer.android.com/reference/android/accounts/AbstractAccountAuthenticator.html 

Abstract base class for creating AccountAuthenticators. In order to be an authenticator one must extend this class, provider implementations for the abstract methods and write a service that returns the result of getIBinder() in the service's onBind(android.content.Intent) when invoked with an intent with actionACTION_AUTHENTICATOR_INTENT. This service must specify the following intent filter and metadata tags in its AndroidManifest.xml file

android.accounts.AbstractAccountAuthenticator是一个虚类，它定义处理Setting->“Accounts&sync”中Account的添加和验证等功能的基本接口，并实现了一些基本功能。AbstractAccountAuthenticator里面有个继承于IAccountAuthenticator.Stub的内部类，以用来对AbstractAccountAuthenticator的远程接口调用进行包装。我们可以通过AbstractAccountAuthenticator的getIBinder（）方法，返回内部类的IBinder形式，以便对AbstractAccountAuthenticator进行远程调用。

     为了能让系统找到我们自制的Account的添加和验证等功能的接口函数，我们需要如下定义一个能接受action为ACTION_AUTHENTICATOR_INTENT的Intent的Service,并在Service的onBind(android.content.Intent)中调AbstractAccountAuthenticator的getIBinder() 返回其用于远程调用的IBinder。

示例1：

   <intent-filter>     <action android:name="android.accounts.AccountAuthenticator" />   </intent-filter>   <meta-data android:name="android.accounts.AccountAuthenticator"             android:resource="@xml/authenticator" /> 

示例2（来自SampleSyncAdapter）：

        <!-- 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>
 

The android:resource attribute must point to a resource that looks like:

Service应该有个名为android.accounts.AccountAuthenticator的meta-data，该meta-data的resource属性所指向的xml文件应该说明该Account在“Accounts&sync”中的基本显示信息

示例3：

 <account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"    android:accountType="typeOfAuthenticator"    android:icon="@drawable/icon"    android:smallIcon="@drawable/miniIcon"    android:label="@string/label"    android:accountPreferences="@xml/account_preferences" /> 

示例4：authenticator文件（来自SampleSyncAdapter）

 <account-authenticator xmlns:android="http://schemas.android.com/apk/res/android"    android:accountType="com.example.android.samplesync"    android:icon="@drawable/icon"    android:smallIcon="@drawable/icon"    android:label="@string/label"/>
 

android:icon,android:smallIcon,android:label属性表示的是你的Account在Setting->“Accounts&sync”中进行显示时的图标和名字 。android:accountType表示的是你的Account的类型，它必须是唯一的。关于Account可参考《Account简介》。The android:accountType attribute must be a string that uniquely identifies your authenticator and will be the same string that user will use when making calls on the AccountManager and it also corresponds to type for your accounts. 使用的android:icon属性的一个地方在 Setting->“Accounts&sync” 设置 ，使用android:smallIcon 属性的一个地方是在Contact Application's tab panels.

android:accountPreferences 属性应该指向一个referenceScreen xml hierarchy that contains a list of PreferenceScreens that can be invoked to manage the authenticator. An example is:

示例5

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">    <PreferenceCategory android:title="@string/title_fmt" />    <PreferenceScreen         android:key="key1"         android:title="@string/key1_action"         android:summary="@string/key1_summary">         <intent             android:action="key1.ACTION"             android:targetPackage="key1.package"             android:targetClass="key1.class" />     </PreferenceScreen> </PreferenceScreen>

The standard pattern for implementing any of the abstract methods is the following:

• If the supplied arguments are enough for the authenticator to fully satisfy the request then it will do so and return a Bundle that contains the results.当提供的参数已经足够的时候，可以直接用Bundler返回结果。
• If the authenticator needs information from the user to satisfy the request then it will create an Intent to an activity that will prompt the user for the information and then carry out the request. This intent must be returned in a Bundle as key KEY_INTENT.

  The activity needs to return the final result when it is complete so the Intent should contain the AccountAuthenticatorResponse asKEY_ACCOUNT_MANAGER_RESPONSE. The activity must then call onResult(Bundle) or onError(int, String) when it is complete.

  当提供的参数不充足的时候，可以新建一个指向某个Activity的Intent，并把传进来的 AccountAuthenticatorResponse 参数以KEY_ACCOUNT_MANAGER_RESPONSE 为键放在Intent，然后把启动Activity的相关参数放入其中，最后把Intent以为键放在Bundle的，并返回该Bundle。

  这样系统将启动我们所指定的Activity，在Activity中完成工作后通过AccountAuthenticatorResponse的onResult(Bundle) or onError(int, String) 返回结果

• If the authenticator cannot synchronously process the request and return a result then it may choose to return null and then use the AccountManagerResponse to send the result when it has completed the request.如果我们想进行的操作是异步操作，而不是同步，可以直接返回null,在操作真正完成后才通过 AccountAuthenticatorResponse 返回操作结果。

The following descriptions of each of the abstract authenticator methods will not describe the possible asynchronous nature of the request handling and will instead just describe the input parameters and the expected result.

When writing an activity to satisfy these requests one must pass in the AccountManagerResponse and return the result via that response when the activity finishes (or whenever else the activity author deems it is the correct time to respond). The AccountAuthenticatorActivity handles this, so one may wish to extend that when writing activities to handle these requests.

主要函数：

Public Methodsabstract BundleaddAccount(AccountAuthenticatorResponse response, String accountType, String authTokenType, String[] requiredFeatures, Bundle options)

Adds an account of the specified accountType.

添加一个我们声明的Account时调用。

注意： accountType是在Mainfest.xml中通过Service的meta-data的android.accounts.AccountAuthenticator属性指向的xml文件的android:accountType属性来声明的

abstract BundleconfirmCredentials(AccountAuthenticatorResponse response, Account account, Bundle options)

Checks that the user knows the credentials of an account.

abstract BundleeditProperties(AccountAuthenticatorResponse response, String accountType)

Returns a Bundle that contains the Intent of the activity that can be used to edit the properties.

BundlegetAccountRemovalAllowed(AccountAuthenticatorResponse response, Account account)

Checks if the removal of this account is allowed.

abstract BundlegetAuthToken(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)

Gets the authtoken for an account.

abstract StringgetAuthTokenLabel(String authTokenType)

Ask the authenticator for a localized label for the given authTokenType.

final IBindergetIBinder()abstract BundlehasFeatures(AccountAuthenticatorResponse response, Account account, String[] features)

Checks if the account supports all the specified authenticator specific features.

abstract BundleupdateCredentials(AccountAuthenticatorResponse response, Account account, String authTokenType, Bundle options)

Update the locally stored credentials for an account.

最后，关于AbstractAccountAuthenticator的使用请参照google官方的示例程序SampleSyncAdapter。