Configuration and acquisition of meta-data extension element data in Manifest in Android learning, manifestmeta-data

Configuration and acquisition of meta-data extension element data in Manifest in Android learning, manifestmeta-data
In the AndroidManifest. xml configuration file, we sometimes see the configuration content starting with the <meta-data...> element similar to the following:

<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" />

Tag <meta-data> provides additional data for the component. It is a key-Value Pair and can be customized. It can be included in the following components:
<Activity>, <application>, <service>, and <worker ER>

1. How to configure the <mate-data...> element:

The tag <meta-data> element configuration syntax is as follows:

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

Note: The general value can be specified through the value attribute, but if you want to specify a resource id, you need to use the resource attribute for configuration.

The configuration is as follows:

<meta-data android:name="api_key" android:value="@string/api_key" />

The specified api_key value is the api_key value stored in the resource file string, for example, AIzaSyBhBFOgVQclaa8p1JJeqaZHiCo2nfiyBBo.

The configuration is as follows:

<meta-data android:name="resId" android:resource="@string/res_id" />

The specified resId value is the ID of the res_id resource instead of the res_id value in the string.


2. How to obtain the value of <mate-data...> element configuration:
1. Configure the <mate-data...> element under the <application...> element.
Xml code segment:

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

Java code segment:

        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();        }

2. Configure the <mate-data...> element under the <activity...> element.
Xml code segment:

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

Java code segment:

Try {ActivityInfo activityInfo = getPackageManager (). getActivityInfo (getComponentName (), PackageManager. GET_META_DATA); // obtain the resource id value of @ string/ice. 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 ();}

3. Configure the <mate-data...> element under the <service...> element.

Xml code segment:

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

Java code segment:

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();}

4. Configure the <mate-data...> element under the <er...> element
Xml code segment:

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

Java code segment:

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();}