android 基礎知識

1. 設置屏幕方向

橫向和豎向切換：

if(getRequestedOrientation() == ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE){
                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
                }else {
                    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
                }

可設置activity默認方向：

<activity android:name=".ActivityMain"
                  android:label="@string/app_name"
                  android:screenOrientation="landscape">

2.設置activity屬性

使activity爲一個窗口：

android :theme="@android:style/Theme.Dialog"

使activity透明：

android:theme="@android:style/Theme.Translucent"

使activity全屏：

android:theme="@android:style/Theme.NoTitleBar.Fullscreen"

3. activity被系統回收時，保存數據

@Override
    protected void onSaveInstanceState(Bundle outState) {
        outState.putInt("id",123);
        super.onSaveInstanceState(outState);
    }

再次啓動時可獲取數值

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if(savedInstanceState != null){
            System.out.println(savedInstanceState.getInt("id"));
        }
        setContentView(R.layout.main);
    }