如何从客户端JavaScript代码访问Java列表元素？

Question

I have the following simple script, which I am using to dynamically create the list elements in a <ul>

<script type="text/javascript">
    function generate(){
        var arr = new Array();
        <c:forEach items="${articles}" var="a" varStatus="status">
            $('#listitems').append(
                "<li>"+${a.title}+"</li>"
            );
            arr[${status.index}] ="${a.slideShow.images}";
        </c:forEach>
    }
</script> 

My problem stems from the images attribute. Every article has a slideshow and every slideshow has a list of images. I want to pull out the very first image from the list of images via the jave list.get(index); I want to do something like "${a.slideShow.images.get(0)}"; . The get() is a java method from the list object.

Any ideas?

Answer 1

In EL you can use the brace notation to access a List element by index. Thus, the following should do:

arr[${status.index}] = "${a.slideShow.images[0]}";

This will behind the scenes do exactly as you proposed: a.getSlideShow().getImages().get(0) .

That said, you normally declare JS arrays like follows:

var arr = [];

The new keyword is considered discouraged in JS.

Answer 2

As those who commented on your question suggest, this is a common misunderstanding. By the time your JavaScript executes (in the browser), Java and JSP and JSTL are no longer available. The JSTL/JSP execute at the server to create source/HTML that is then sent to the client.

View source on your page - it might shed some light. You should not see the JSP/JSTL you include above.