Android开发实现模仿微信小窗口功能【Dialog对话框风格窗口】

<?xml version="1.0" encoding="utf-8" ? 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/idtatabHost"
  android:layout_width="300dp"
  android:layout_height="500dp"
  android:layout_gravity="center"
  android:layout_weight="1" 
  <ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:src="@drawable/wechat"
    android:scaleType="fitXY"/ 
  <TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="假的 WeChat"
    android:textSize="20dp"
    android:textColor="#ffffffff"/ 
  <Button
    android:id="@+id/send"
    android:onClick="send"
    android:text="点我一下 有惊喜（吓） 。。。"
    android:textColor="#ffffffff"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"/ 
</RelativeLayout 

public class MainActivity extends Activity {
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }
  public void send(View source){
    finish();
  }
}

  <application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme" 
    <activity
      android:name=".MainActivity"
      android:label="@string/app_name"
      android:theme="@android:style/Theme.Material.Dialog"
      tools:targetApi="lollipop" 
      <intent-filter 
        <action android:name="android.intent.action.MAIN" / 
        <category android:name="android.intent.category.LAUNCHER" / 
      </intent-filter 
    </activity 
  </application