GCM 注册 ID 为空

您好，我正在尝试实施 GCM 推送通知。我得到一个空的 GCM ID。 这是我的代码：

public void registerClient() {

        try {
        // Check that the device supports GCM (should be in a try / catch)
        GCMRegistrar.checkDevice(this);
        GCMRegistrar.checkManifest(this);
        regId = GCMRegistrar.getRegistrationId(this);


        if (regId.equals("")) {
            registrationStatus = "Registering...";
            GCMRegistrar.register(this, PROJECT_ID);
            regId="sfsaas";
            regId = GCMRegistrar.getRegistrationId(this);
            registrationStatus = "Registration Acquired";
            Log.i("******IN_IF_REGID*****", regId);
            Log.i("INSIDE","if");
        } 
        else 
        {
            Log.i("INSIDE","else");
            registrationStatus = "Already registered";
            Log.i("******REGID*****", regId);
        }

        } 
        catch (Exception e) {
            e.printStackTrace();
            registrationStatus = e.getMessage();
        }

}

这是我的清单：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.eventnotifier"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="17" />

<permission
    android:name="com.example.eventnotifier.permission.C2D_MESSAGE"
    android:protectionLevel="signature" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"     />
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />
    <uses-permission android:name="android.permission.READ_CONTACTS"/>
    <uses-permission android:name="com.example.eventnotifier.permission.C2D_MESSAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" /> 

<!-- Camera permission -->
    <uses-feature android:name="android.hardware.camera" />
<!-- receives GCM messages -->
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />

<!-- GCM connects to Google services -->
    <uses-permission android:name="android.permission.INTERNET" />

<!-- GCM requires a Google account -->
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />

    <uses-permission android:name="android.permission.USE_CREDENTIALS" />

    <uses-permission android:name="android.permission.READ_OWNER_DATA" />

<!-- wake the processor if a GCM message is received -->
    <uses-permission android:name="android.permission.WAKE_LOCK" />
<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@android:color/black" >

    <receiver android:name="com.google.android.gcm.GCMBroadcastReceiver"     android:permission="com.google.android.c2dm.permission.SEND" >
        <intent-filter>
            <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
            <category android:name="com.example.eventnotifier" />
        </intent-filter>
    </receiver>

    <service android:name=".GCMIntentService" />
        <activity
            android:name="com.example.eventnotifier.HomeActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait" >
        </activity>

        <activity
            android:name="com.example.eventnotifier.RegisterActivity"
            android:label="@string/app_name"
            android:screenOrientation="portrait" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
        </activity>

     <activity
        android:name="com.example.eventnotifier.DateActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

    <activity
        android:name="com.example.eventnotifier.DescriptionActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.MyEventActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.CreateEventActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.LocationActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.AddGuestActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.ContactListActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.ContactTest"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.InvitedGuestsActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.MyInvitationsActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.UnregisteredGuestsActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">
     </activity>

     <activity
        android:name="com.example.eventnotifier.RecentGuestsActivity"
        android:label="@string/app_name" 
        android:screenOrientation="portrait">

     </activity>
 </application>  
</manifest>

此行不会被打印 -Log.i("**IN_IF_REGID***", regId); 你们能帮我吗？ 我明天必须提交这个项目。任何帮助将不胜感激！ 谢谢

它不是那样工作的。

GCMRegistrar.register向 GCM 服务器发起请求，要求其提供注册 ID。这是一个异步请求。GCMRegistrar.getRegistrationId返回注册 ID 的缓存值，因此如果您的设备未注册，则返回 null。

注册 ID 返回在GCMIntentService.onRegistered method.

这是代码GCM意图服务来自 GCM 演示。

这是代码GCMRegistrar.getRegistrationId :

/**
 * Gets the current registration id for application on GCM service.
 * <p>
 * If result is empty, the registration has failed.
 *
 * @return registration id, or empty string if the registration is not
 *         complete.
 */
public static String getRegistrationId(Context context) {
    final SharedPreferences prefs = getGCMPreferences(context);
    String registrationId = prefs.getString(PROPERTY_REG_ID, "");
    // check if app was updated; if so, it must clear registration id to
    // avoid a race condition if GCM sends a message
    int oldVersion = prefs.getInt(PROPERTY_APP_VERSION, Integer.MIN_VALUE);
    int newVersion = getAppVersion(context);
    if (oldVersion != Integer.MIN_VALUE && oldVersion != newVersion) {
        Log.v(TAG, "App version changed from " + oldVersion + " to " +
                newVersion + "; resetting registration id");
        clearRegistrationId(context);
        registrationId = "";
    }
    return registrationId;
}

正如您所看到的，它返回本地存储的注册 ID 值。为了让它返回任何东西，GCMRegistrar.setRegistrationId(Context context, String regId)必须使用返回的注册 ID 进行调用GCMIntentService。 它被称为GCMBaseIntentService :

    private void handleRegistration(final Context context, Intent intent) {
        GCMRegistrar.cancelAppPendingIntent();
        String registrationId = intent.getStringExtra(EXTRA_REGISTRATION_ID);
        String error = intent.getStringExtra(EXTRA_ERROR);
        String unregistered = intent.getStringExtra(EXTRA_UNREGISTERED);
        Log.d(TAG, "handleRegistration: registrationId = " + registrationId +
                ", error = " + error + ", unregistered = " + unregistered);

        // registration succeeded
        if (registrationId != null) {
            GCMRegistrar.resetBackoff(context);
            GCMRegistrar.setRegistrationId(context, registrationId);
            onRegistered(context, registrationId);
            return;
        }
    ...
    }