Android PopupWindow使用时注意

项目中使用PopupWindown出现的坑

1、部分设备，PopWindow在Android4.0后版本，出现NullPointerException调用以下方法可解决， fixPopupWindow(p)在实例化后调用

/**
 * 在new PopupWindow()后调用 兼容4.0(ICE_CREAM_SANDWICH)以下版本 <br>
 * 防止错误<br>
 * java.lang.NullPointerException<br>
 * at android.widget.PopupWindow$1.onScrollChanged(PopupWindow.java:
 * 
 * @param window
 */
public static void fixPopupWindow(final PopupWindow window) {
    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        try {
            final Field fAnchor = PopupWindow.class
                    .getDeclaredField("mAnchor");
            fAnchor.setAccessible(true);
            Field listener = PopupWindow.class
                    .getDeclaredField("mOnScrollChangedListener");
            listener.setAccessible(true);
            final ViewTreeObserver.OnScrollChangedListener originalListener = (ViewTreeObserver.OnScrollChangedListener) listener
                    .get(window);
            ViewTreeObserver.OnScrollChangedListener newListener = new ViewTreeObserver.OnScrollChangedListener() {
                @Override
                public void onScrollChanged() {
                    try {
                        @SuppressWarnings("unchecked")
                        WeakReference<View> mAnchor = (WeakReference<View>) fAnchor
                                .get(window);
                        if (mAnchor == null || mAnchor.get() == null) {
                            return;
                        } else {
                            originalListener.onScrollChanged();
                        }
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    }
                }
            };
            listener.set(window, newListener);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

2、在想要实现点击返回键后popupWindow自动消失时，返现popupWindow为null。请为popupWindow设置一个背景

popWindow.setFocusable(true);
popWindow.setBackgroundDrawable(new PaintDrawable(0x88000000));
popWindow.setOutsideTouchable(true);