comment pouvez régler la carte de la clé api dans android studio?

Je suis en utilisant Google map dans mon projet, la carte est en cours d'ouverture, mais pas de chargement. Je suis nouveau sur android studio,je ne sais pas comment définir la carte clé dans android studio,

S'il vous plaît aider moi.

fichier manifeste est

     <?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="com.truiton.supportmapfragment.permission.MAPS_RECEIVE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<!--
The following two permissions are not required to use
Google Maps Android API v2, but are recommended.
-->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:allowBackup="true"
android:icon="@drawable/logo"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme" >
<activity
android:name=".activities.SplashScreen"
android:label="@string/app_name"
android:theme="@style/AppTheme.NoActionBar" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".activities.MainActivity" />
<activity
android:name=".activities.ForCustomer"
android:label="@string/title_activity_for_customer"
android:theme="@style/AppTheme.NoActionBar" >
</activity>
<activity
android:name=".activities.CustomerSignIn"
android:label="@string/title_activity_customer_sign_in"
android:theme="@style/AppTheme.NoActionBar" >
</activity>
<activity
android:name=".activities.Home"
android:label="@string/title_activity_home"
android:theme="@style/AppTheme.NoActionBar" >
</activity>
<activity
android:name=".activities.RegisterCustomer"
android:label="@string/title_activity_register_customer"
android:theme="@style/AppTheme.NoActionBar" >
</activity>
<uses-feature
android:glEsVersion="0x00020000"
android:required="true"/>
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<meta-data android:name="com.google.android.maps.v2.API_KEY" android:value="I_REMOVED"/>
</application>

fichier xml en utilisant comme ce

<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<RelativeLayout
android:id="@+id/header"
android:layout_width="fill_parent"
android:layout_height="50dp"
android:background="#1B8AB7">
<ImageView
android:id="@+id/menu"
android:layout_width="40dp"
android:layout_height="25dp"
android:src="@drawable/menu"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_marginLeft="10dp"/>
<RelativeLayout
android:id="@+id/realtivelayout_search_bar"
android:layout_width="250dp"
android:layout_centerHorizontal="true"
android:layout_height="30dp"
android:layout_centerVertical="true"
android:background="@drawable/saerchbarbackground"
>
<ImageView
android:id="@+id/btn_searchbar"
android:layout_width="35dp"
android:layout_height="match_parent"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:src="@drawable/search_btn"
android:layout_marginRight="5dp"/>
<EditText
android:layout_marginLeft="5dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:id="@+id/edittext_searchbar"
android:layout_toLeftOf="@+id/btn_searchbar"
android:hint=" search for location"
android:singleLine="true"
android:textColor="#000000"
android:background="#00000000"
/>
</RelativeLayout>
</RelativeLayout>
<fragment
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@+id/header"
/>
</RelativeLayout>

J'ai Utilisé la carte de l'api comme vous l'avez dit, mais la carte ne se chargent pas encore.