自己总结的一点知识，希望大佬批评指正，望后人借鉴

public class CustomPopWindow extends PopupWindow {
    private static final String TAG = "CustomPopWindow";
    private final View view;
    private Activity context;
    private int viewdata;
    public CustomPopWindow(Activity context,int type,int width,int Height) {
        super(context);
        switch (type){
            case 1:
            //这里赋值自定义页面为提高代码灵活性
                  viewdata=R.layout.widget_popupwindow;
                break;
            case 2:
                  viewdata=R.layout.widget_popupwindow2;
                break;
            case 3:
                viewdata=R.layout.widget_popupwindow3;
                break;
            case 4:
//                viewdata=R.layout.widget_popupwindow4;
                break;
        }
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        view = inflater.inflate(viewdata, null);
        //alt+ctrl+f

        this.context = context;
        initView(type);
        initPopWindow(width,Height);
    }


    private void initView(int type) {


        switch (type){
            case 1:
                Button cancelTv = view.findViewById(R.id.btn2);
                cancelTv.setFocusable(true);
                cancelTv.setFocusableInTouchMode(true);
                cancelTv.requestFocus();
                cancelTv.requestFocusFromTouch();


                cancelTv.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        dismiss();
                    }
                });
                break;
            case 2:
                Button btn3 = view.findViewById(R.id.btn3);
                Button btn4 = view.findViewById(R.id.btn4);
                btn3.setFocusable(true);
                btn3.setFocusableInTouchMode(true);
                btn3.requestFocus();
                btn3.requestFocusFromTouch();

                btn3.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        dismiss();
                    }
                });
                break;

        }
        }



    private void initPopWindow(int width ,int Height) {
        this.setContentView(view);
        // 设置弹出窗体的宽
        this.setWidth(width);
        // 设置弹出窗体的高
        this.setHeight(Height);
        // 设置弹出窗体可点击()
        this.setFocusable(true);
        this.setOutsideTouchable(true);
        // 实例化一个ColorDrawable颜色为半透明
        ColorDrawable dw = new ColorDrawable(0x00FF00);
        //设置弹出窗体的背景
        this.setBackgroundDrawable(dw);
        backgroundAlpha(context, 0.5f);//0.0-1.0
    }

    /**
     * 设置添加屏幕的背景透明度(值越大,透明度越高)
     *
     * @param bgAlpha
     */
    public void backgroundAlpha(Activity context, float bgAlpha) {
        WindowManager.LayoutParams lp = context.getWindow().getAttributes();
        lp.alpha = bgAlpha;
        context.getWindow().addFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
        context.getWindow().setAttributes(lp);
    }

}

接下来布局代码

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/shape_corner_down">

    <TextView
        android:id="@+id/textView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="TextView"
        android:textColor="@color/white" />

    <Button
        android:id="@+id/btn3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentBottom="true"
        android:layout_marginRight="20dp"
        android:text="点击确定"
        android:background="@drawable/custombutton"
        android:layout_centerInParent="true"/>

    <Button
        android:id="@+id/btn4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentBottom="true"
        android:layout_marginLeft="20dp"
        android:text="点击退出"
        android:background="@drawable/custombutton"
        android:layout_centerInParent="true"/>

</RelativeLayout>

按钮样式

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <!-- 定义当button 处于pressed 状态时的形态。-->
        <shape>
            <gradient android:startColor="#8600ff" /><!--内容实现渐变-->
            <stroke android:width="1dp" android:color="#000000" /><!--边框宽度和颜色-->
            <corners android:radius="5dp" /><!--圆弧半径-->
            <padding android:left="10dp" android:top="10dp"
                android:bottom="10dp" android:right="10dp" />
        </shape>
    </item>
    <item android:state_focused="true">
    <!-- 定义当button获得focus时的形态-->
    <shape>
        <gradient android:endColor="#eac100" />
        <stroke android:width="2dp" android:color="#333333"  />
        <corners android:radius="8dp" />
        <padding android:left="10dp" android:top="10dp"
            android:bottom="10dp" android:right="10dp" />
    </shape>
    </item>
</layer-list>

布局圆角

<?xml version="1.0" encoding="utf-8"?>
<!--定义布局圆角-->
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <solid android:color="#000000" />
    <corners android:bottomRightRadius="20dp"
        android:bottomLeftRadius="20dp"/>
    <stroke android:width="1dp" android:color="#000000"/>
</shape>

引用

//                customPopWindow=new CustomPopWindow(getActivity(),2,800,300);
//                customPopWindow.showAtLocation(view,
//                        Gravity.TOP | Gravity.CENTER_HORIZONTAL, 0, 0);
//                customPopWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {
//                    @Override
//                    public void onDismiss() {
//                        customPopWindow.backgroundAlpha( getActivity(), 1f);
//                    }
//                });

效果图