Can you call a servlet with a link?

问题

Can you call a servlet with a link? For example

<a href="/servletName">link text</a>

And possibly pass parameters to the request object by adding them to the querystring.

If not, I have seen this kind of thing:

RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(/MyServlet); 
dispatcher.include(request,response);

But how would I trigger this? For example if it was JavaScript code I could put it within a jQuery click function, or if this was a servlet I would put it into a method.

But how do I call this code from within a JSP. As far as I know you can't call Java code with JavaScript events.

回答1:

<a href="servletUrl?param=value">click</a>

is perfectly legal and will work.

That will make the doGet(..) method of the servlet be called, and you can get the parameter using request.getParameter("param")

回答2:

Just to clear a misconception:

As far as I know you can't call Java code with Javascript events.

You can perfectly call Java code with JavaScript code (and events). To the point, you just need to let JavaScript send a fullworthy HTTP request to the server side. There are basically 3 ways for this.

The first way is to simulate invocation of an existing link/button/form. E.g.

<a id="linkId" href="http://www.google.com/search?q=balusc">Link</a>

<script type="text/javascript">
    document.getElementById('linkId').click();
</script>

and

<form id="formId" action="http://www.google.com/search">
    <input type="text" id="inputId" name="q">
</form>

<script type="text/javascript">
    document.getElementById('inputId').value = 'balusc';
    document.getElementById('formId').submit();
</script>

The second way is to use window.location to fire a plain GET request. For example:

<script type="text/javascript">
    var search = 'balusc';
    window.location = 'http://www.google.com/search?q=' + search;
</script>

The third way is to use XMLHttpRequest object to fire an asynchronous request and process the results. This technique is the base idea of "Ajax". Here's a Firefox compatible example:

<script type="text/javascript">
    function getUrl(search) {
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function() {
            if (xhr.readyState == 4) {
                var responseJson = eval('(' + xhr.responseText + ')');
                var url = responseJson.responseData.results[0].unescapedUrl;
                var link = document.getElementById('linkId');
                link.href = link.firstChild.nodeValue = url;
                link.onclick = null;
            }
        }
        var google = 'http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q='
        xhr.open('GET', google + search, true);
        xhr.send(null);
    }
</script>

<p>My homepage is located at: <a id="linkId" href="#" onclick="getUrl('balusc')">click me!</a></p>

This can be rewritten in a shorter and crossbrowsercompatible manner with jQuery.

Just substitute http://www.google.com/search with your own servlet to get the above examples to work in your environment.

For more background information, you may find this article useful as well.

回答3:

Perhaps the following is what you're after:

<jsp:include page="/MyServlet">
    <jsp:param name="param" value="value"/>
</jsp:include>

来源：https://stackoverflow.com/questions/2267064/can-you-call-a-servlet-with-a-link

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java

javascript

jsp

servlets

argument-passing