实现一个简单popupWindow的简单封装类

public class PopupUtils {
    private PopupWindow popupWindow;
    private Activity activity;

    public PopupUtils(Activity activity, View contentView) {
        this.activity = activity;
        popupWindow = new PopupWindow(activity);
        popupWindow.setContentView(contentView);
        popupWindow.setHeight(LinearLayout.LayoutParams.WRAP_CONTENT);
        popupWindow.setWidth(LinearLayout.LayoutParams.WRAP_CONTENT);
        popupWindow.setOutsideTouchable(true);
        popupWindow.setFocusable(true);
        popupWindow.setBackgroundDrawable(new BitmapDrawable());
    }

    public void show(View parent) {
        popOutShadow(popupWindow, activity);
        popupWindow.showAtLocation(parent, Gravity.CENTER, 0, 0);//相对于父窗口
    }

    public void dismiss() {
        if (popupWindow.isShowing()) {
            popupWindow.dismiss();
        }
    }

    public void popOutShadow(PopupWindow popupWindow, final Activity activity) {
        WindowManager.LayoutParams lp = activity.getWindow().getAttributes();
        lp.alpha = 0.7f;
        activity.getWindow().setAttributes(lp);
        popupWindow.setOnDismissListener(new PopupWindow.OnDismissListener() {

            @Override
            public void onDismiss() {
                WindowManager.LayoutParams lp = activity.getWindow().getAttributes();
                lp.alpha = 1f;
                activity.getWindow().setAttributes(lp);
            }
        });
    }
}