Android自定义dialog 单利模式

package com.newingscom.fpimlockscreen;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.view.View;

/**
 * Created by Administrator on 2019/4/1 0001.
 */

public class MSDialogManager {
    private static MSDialogManager msDialogManager = new MSDialogManager();
    private AlertDialog alertDialog;

    public static MSDialogManager newInstance() {
        return msDialogManager;
    }

    public void showDialog(Context context) {
        if (alertDialog == null) {
            AlertDialog.Builder builder = new AlertDialog.Builder(context, R.style.MyDialog);
            View alView = View.inflate(context, R.layout.dialog_lockscreen_lock_remind, null);
            builder.setView(alView);
            alertDialog = builder.create();
            alertDialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
                @Override
                public void onDismiss(DialogInterface dialogInterface) {
                    alertDialog = null;
                }
            });
        }
        alertDialog.show();
    }


    public void dismissDialog() {
        if (alertDialog != null) {
            alertDialog.dismiss();
            alertDialog = null;

        }

    }


}

  <style name="MyDialog" parent="@android:style/Theme.Holo.Dialog">
        <!-- 是否有边框 -->
        <item name="android:windowFrame">@null</item>
        <!--是否在悬浮Activity之上  -->
        <item name="android:windowIsFloating">true</item>
        <!-- 标题 -->
        <item name="android:windowNoTitle">true</item>
        <!--阴影  -->
        <item name="android:windowIsTranslucent">true</item><!--半透明-->
        <!--背景透明-->
        <item name="android:windowBackground">@android:color/transparent</item>
        <!-- 还可以加入一些弹出和退出的动画 (lan)-->
    </style>

    <!--对话框的样式-->
    <style name="NormalDialogStyle">
        <!--对话框背景 -->
        <item name="android:windowBackground">@android:color/transparent</item>
        <!--边框 -->
        <item name="android:windowFrame">@null</item>
        <!--没有标题 -->
        <item name="android:windowNoTitle">true</item>
        <!-- 是否浮现在Activity之上 -->
        <item name="android:windowIsFloating">true</item>
        <!--背景透明 -->
        <item name="android:windowIsTranslucent">false</item>
        <!-- 是否有覆盖 -->
        <item name="android:windowContentOverlay">@null</item>

        <!--背景变暗-->
        <item name="android:backgroundDimEnabled">true</item>
    </style>