Android PopupWindow弹窗动态显示在View的上下方，

序、周末不加班，

效果图如下。

我们要弹出的PopupWindow在View的下方，如果下方区域不够，则弹出在上方。

实现方案思路

我们在显示的时候，首先去计算一下弹窗高度。使用屏幕的高 - popupwind的高并且和popup的高做对比，如果大于的话，则显示在下方，如果小于的话，则显示在上方。

 /**** @param anchorView 锚点View* @param contentView 弹出的View* @return*/private int[] calculatePopWindowPos(final View anchorView, final View contentView) {final int[] windowPos = new int[2];final int[] anchorLoc = new int[2];// 获取锚点View在屏幕上的左上角坐标位置anchorView.getLocationOnScreen(anchorLoc);final int anchorHeight = anchorView.getHeight();// 获取屏幕的高宽final int screenHeight = getScreenHeight(anchorView.getContext());final int screenWidth = getScreenWidth(anchorView.getContext());contentView.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);// 计算contentView的高宽final int windowHeight = contentView.getMeasuredHeight();final int windowWidth = contentView.getMeasuredWidth();// 判断需要向上弹出还是向下弹出显示final boolean isNeedShowUp = (screenHeight - anchorLoc[1] - anchorHeight < windowHeight);Log.i("AAAA", "screenWidth = "+screenWidth+"---"+"windowWidth="+windowWidth);if (isNeedShowUp) {windowPos[0] = (screenWidth - windowWidth)/2;windowPos[1] = anchorLoc[1] - windowHeight;} else {windowPos[0] = (screenWidth - windowWidth)/2;windowPos[1] = anchorLoc[1] + anchorHeight;}return windowPos;}

显示popupwindow如下

 Button btn1 = findViewById(R.id.btn1);btn1.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {View contentView = LayoutInflater.from(ListActivity.this).inflate(R.layout.layout_window, null);PopupWindow popupWindow = new PopupWindow(contentView,ViewGroup.LayoutParams.WRAP_CONTENT , ViewGroup.LayoutParams.WRAP_CONTENT);// 设置PopupWindow可以获得焦点，否则无法响应点击事件popupWindow.setFocusable(true);
//                popupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));int[] windowPos = calculatePopWindowPos(view, contentView);// 3. 显示PopupWindowpopupWindow.showAtLocation(view,Gravity.TOP|Gravity.START, windowPos[0], windowPos[1]);}});

完毕。