android中popupwindow的实现，弹出后页面变暗

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingRight="15dp" >

<TextView
android:id="@+id/tv_text_book_pop_window_renjiao"
android:layout_width="100dp"
android:layout_height="49.5dp"
android:layout_alignParentRight="true"
android:layout_marginRight="15dp"
android:text="人教版"
android:textColor="@color/action_bar_background"
android:gravity="center"
android:background="@color/white"/>

<View
android:id="@+id/view_text_book_pop_window_line"
android:layout_width="100dp"
android:layout_height="0.5dp"
android:layout_alignParentRight="true"
android:layout_marginRight="15dp"
android:background="#d0d0d0"
android:layout_below="@id/tv_text_book_pop_window_renjiao"/>

<TextView
android:id="@+id/tv_text_book_pop_window_beishida"
android:layout_width="100dp"
android:layout_height="49.5dp"
android:layout_alignParentRight="true"
android:layout_marginRight="15dp"
android:text="北师大版"
android:textColor="#8e8e8e"
android:gravity="center"
android:layout_below="@id/view_text_book_pop_window_line"
android:background="@color/white"/>

<View
android:layout_width="100dp"
android:layout_height="0.5dp"
android:background="#d0d0d0"
android:layout_alignParentRight="true"
android:layout_marginRight="15dp"
android:layout_below="@id/tv_text_book_pop_window_beishida"/>

</RelativeLayout>

可以见得，就是简单的relativelayout

下面是程序中的代码

<pre name="code" class="java">//popUpWindow显示，教材版本private void showVersionPopWindow(View parent){// 一个自定义的布局，作为显示的内容View contentView = LayoutInflater.from(context).inflate(R.layout.text_book_pop_window_version, null);// 设置按钮的点击事件//各种设置versionPopWindow = new PopupWindow(contentView, LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT, true);// 这个是为了点击“返回Back”也能使其消失，并且并不会影响背景versionPopWindow.setBackgroundDrawable(new BitmapDrawable());versionPopWindow.setTouchable(true);// 使其聚集versionPopWindow.setFocusable(true);// 设置允许在外点击消失versionPopWindow.setOutsideTouchable(true);// 设置消失的监听versionPopWindow.setOnDismissListener(popDismissListener);//相对的偏移量int xPos = 0;int yPos = 0;//设置背景透明backgroundTextView.setVisibility(View.VISIBLE);//显示popUpWindowversionPopWindow.showAsDropDown(parent, xPos, yPos);}