Android 从下往上弹出 DialogFragment 的关键代码

//java代码：
public class CountrySelectDialog extends AppCompatDialogFragment{

  public static CountrySelectDialog newInstance() {
    Bundle args = new Bundle();
    CountrySelectDialog fragment = new CountrySelectDialog();
    fragment.setArguments(args);
    return fragment;
  }

  @Override
  public void onStart() {
    super.onStart();
    setStyle(AppCompatDialogFragment.STYLE_NORMAL, R.style.BottomDialog);//设置自定义style

    Window window = getDialog().getWindow();
    window.setBackgroundDrawable(null);//必须的
    WindowManager.LayoutParams lp = window.getAttributes();
    lp.gravity = Gravity.BOTTOM;//在下边
    lp.width = WindowManager.LayoutParams.MATCH_PARENT;
    window.setAttributes(lp);

    getDialog().setOnDismissListener(dialog -> {
      	//todo，关闭dialog的回调监听
      }
    });

  }

  @Override
  public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
      @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.xxx, container, false);
  }

  public void show(FragmentManager supportFragmentManager) {
    show(supportFragmentManager, getClass().getName());
    setStyle(AppCompatDialogFragment.STYLE_NORMAL, R.style.BottomDialog);//show的时候设置，不然第一次style无效
  }

}


//styles.xml代码：
<style name="BottomDialog" parent="Theme.AppCompat.Light.Dialog">
  <item name="android:windowAnimationStyle">@style/BottomDialogAnimation</item>
</style>

<style name="BottomDialogAnimation">
  <item name="android:windowEnterAnimation">@anim/bottom_dialog_in</item>
  <item name="android:windowExitAnimation">@anim/bottom_dialog_out</item>
</style>


// res/anim/bottom_dialog_in.xml
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
  android:interpolator="@android:anim/accelerate_interpolator"
  >
  <translate
    android:duration="300"
    android:fillAfter="true"
    android:fromXDelta="0"
    android:fromYDelta="100%"
    android:toXDelta="0"
    android:toYDelta="0">

  </translate>
  <alpha
    android:duration="300"
    android:fromAlpha="0.0"
    android:toAlpha="1.0"/>
</set>

// res/anim/bottom_dialog_out.xml
<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
  android:interpolator="@android:anim/accelerate_interpolator">
  <translate
    android:duration="300"
    android:fillAfter="true"
    android:fromXDelta="0"
    android:fromYDelta="0"
    android:toXDelta="0"
    android:toYDelta="100%">

  </translate>
  <alpha
    android:duration="300"
    android:fromAlpha="1.0"
    android:toAlpha="0.0"/>
</set>