手螢幕顯示/橫向/直向

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);//設定螢幕不隨手機旋轉
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);//螢幕保持橫向
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);//螢幕保持直向
getRequestedOrientation();//獲取螢幕方向，0為橫向1為直向
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);//螢幕不關閉

示範

XML

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/t1"
        android:layout_width="wrap_content"
        android:layout_height="16dp"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

JAVA

public class MainActivity extends AppCompatActivity {
TextView t1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       // setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_NOSENSOR);//設定螢幕不隨手機旋轉
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);//螢幕保持橫向
       // setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);//螢幕保持直向
      //  getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);//螢幕不關閉
        t1=(TextView)findViewById(R.id.t1);
        t1.setText(""+getRequestedOrientation());
    } 

} 

資料來源: https://kk665403.pixnet.net/blog/post/403248326-android-screendirection