在struts中，我注意到有两种访问变量的不同方法.我很好奇这是什么区别，以及何时正确使用它们之间的区别.例如，假设我们像这样设置变量高度:

In struts I notice there are two different ways to access variables. I am curious what the difference is and when to properly use each one. For example, suppose we set the variable height like so:

<s:set var="height">300px</s:set>

现在我可以用两种方式使用它:

Now I can use it two ways:

<div style="height: ${height}">&nbsp;</div>

.. or ..

<div style="height: <s:property value='#height' />">&nbsp;</div>

有什么区别，哪个更好用?

What is the difference, and which is better to use?