1. 設定Dialog在視窗底部，且寬度最大。

Window window = getDialog().getWindow();
WindowManager.LayoutParams layoutParams = window.getAttributes();
layoutParams.gravity = Gravity.BOTTOM;
layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
window.setAttributes(layoutParams);

 或 使用Dialog可類似處理，進行螢幕位置的設定。

Window window = getDialog().getWindow();
 
WindowManager.LayoutParams layoutParams = window.getAttributes();
layoutParams.gravity = Gravity.CENTER; //居中顯示window.setAttributes(layoutParams);

設定對話方塊外部背景

getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT)); //去掉背景色

設定主題

getDialog().requestWindowFeature(Window.FEATURE_NO_TITLE
 
);

例項：

public class WifiListDialog extends DialogFragment {
    private Context mContext;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
mContext = getActivity();
}

    @Override
public View onCreateView(LayoutInflater inflater, 
 
@Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_wifi_dialog, null);
getDialog().requestWindowFeature(Window.FEATURE_NO_TITLE);
getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT)); //去掉背景色（一些裝置上由於系統主題原因會有背景邊框）
Window window = getDialog().getWindow();
WindowManager.LayoutParams layoutParams = window.getAttributes();
layoutParams.gravity = Gravity.BOTTOM;
layoutParams.width = WindowManager.LayoutParams.MATCH_PARENT;
window.setAttributes(layoutParams);
initView(view);
        return view;
}
   ...
}

2. Activity也可作為Dialog使用，使用Activity作為對話方塊使用時，若希望寬度佔滿螢幕，則需要進行如下設定： 設定Activity主題（以Dialog風格顯示）：

<style name="ActivityDialog" parent="Theme.AppCompat.Dialog">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowBackground">@null</item> //必須設定該屬性為空，才能佔滿螢幕，否則會有邊界空白</style>

<activity android:name=".module.homepage.ActivitySelectDevice"
android:theme="@style/ActivityDialog"
android:launchMode="singleTop"/>

在Activity的oncreate()方法中設定寬度佔滿屏（同理，可設定寬度具體大小）

public class ActivitySelectDevice extends Activity {
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_xxx);
Display display = getWindowManager().getDefaultDisplay();
WindowManager.LayoutParams layoutParams = getWindow().getAttributes();
layoutParams.width = display.getWidth();
getWindow().setAttributes(layoutParams);
}}

   或 （這兩種方式實際是一樣的）

DisplayMetrics dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
getWindow().setLayout(dm.widthPixels, getWindow().getAttributes().height);

注意：如果只是設定了佈局寬度，而沒有將 android:windowBackground 屬性置為 null，那麼對話方塊寬度不能佔滿屏，會有邊界區域。 3. 設定Dialog的大小（寬高）

public class AppDialog extends Dialog {

    public AppDialog(Context context) {
        super(context, R.style.dialogTheme);
View view = LayoutInflater.from(context).inflate(R.layout.dialog_xxx, null);setContentView(view);
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay(); //獲取螢幕寬高
Point point = new Point();
display.getSize(point);
Window window = getWindow();
WindowManager.LayoutParams layoutParams = window.getAttributes(); //獲取當前對話方塊的引數值
layoutParams.width = (int) (point.x * 0.5); //寬度設定為螢幕寬度的0.5
layoutParams.height = (int) (point.y * 0.5); //高度設定為螢幕高度的0.5
//        layoutParams.width = (int) (display.getWidth() * 0.5);
//        layoutParams.height = (int) (display.getHeight() * 0.5);
window.setAttributes(layoutParams);
}
}