让Android程序单例运行

<?xml

xxxx?>

<manifest

xxxxxxx>

    <application

android:icon="@drawable/icon"

          android:label="@string/app_name"

        android:launchMode="singleInstance">

    <activity

android:name=".Main"

          android:label="Main
Window"

          android:icon="@drawable/icon>

        <intent-filter>

            <action

android:name="android.intent.action.MAIN"

/>

            <category

android:name="android.intent.category.LAUNCHER"/>

        </intent-filter>

     <activity

xxxxxxxxx/>

</manifest>

XML第五行。。。