Android Manifest中meta-data扩展元素数据的配置与获取方式

<meta-data
  android:name="com.google.android.maps.v2.API_KEY"
  android:value="AIzaSyBhBFOgVQclaa8p1JJeqaZHiCo2nfiyBBo" />
<meta-data
  android:name="com.google.android.gms.version"
  android:value="@integer/google_play_services_version" />

<meta-data android:name="string"
   android:resource="resource specification"
   android:value="string" />

<application...>
  .....
  <meta-data
     android:name="api_key"
     android:value="AIzaSyBhBFOgVQclaa8p1JJeqaZHiCo2nfiyBBo" />
</application>

    try {
      ApplicationInfo appInfo = getPackageManager().getApplicationInfo(getPackageName(),
          PackageManager.GET_META_DATA);
      String value = appInfo.metaData.getString("api_key");
      Log.d("Tag", " app key : " + value); // Tag﹕ app key : AIzaSyBhBFOgVQclaa8p1JJeqaZHiCo2nfiyBBo
    } catch (PackageManager.NameNotFoundException e) {
      e.printStackTrace();
    }

<activity ...>
  .....
  <meta-data android:name="resource_id"
     android:resource="@string/ice" />
</activity>

    try {
      ActivityInfo activityInfo = getPackageManager().getActivityInfo(getComponentName(),
          PackageManager.GET_META_DATA);
      // 获取到的是 @string/ice 对应的资源id值
      int value = activityInfo.metaData.getInt("resource_id");
      Log.d("Activity Tag", "resource_id : " + value); // Activity Tag﹕ resource_id : 2131361808
    } catch (PackageManager.NameNotFoundException e) {
      e.printStackTrace();
    }

<service android:name="MetaDataService">
   .....
   <meta-data android:name="service_meta_data" android:value="xxxxxxx" />
</service>

try {
   ComponentName cn=new ComponentName(this, MetaDataService.class);
   ServiceInfo info=this.getPackageManager()
        .getServiceInfo(cn, PackageManager.GET_META_DATA);
   String value = info.metaData.getString("service_meta_data");
   Log.d("Service TAG", " value == " + value);
} catch (PackageManager.NameNotFoundException e) {
   e.printStackTrace();
}

<receiver android:name="MetaDataReceiver">
   .....
   <meta-data android:name="receiver_meta_data" android:value="xxxxxxx" />
</receiver>

try {
   ComponentName cn=new ComponentName(this, MetaDataReceiver.class);
   ActivityInfo info=context.getPackageManager()
               .getReceiverInfo(cn, PackageManager.GET_META_DATA);
   String value = info.metaData.getString("receiver_meta_data");
   Log.d("Receiver TAG", " value == " + value);
} catch (PackageManager.NameNotFoundException e) {
   e.printStackTrace();
}