Grails操作被调用两次。救命啊!

我正在写一个grails应用程序,遇到了一个奇怪的问题。当单击页面上的submit按钮时,关联的操作会被快速连续调用两次。这会让一切变得可怕。其他人以前见过这个问题吗?以下是我的代码:

从GSP页面:

<g:form method="post" action="show">
<h2>All items since...</h2>
<g:datePicker name="startDate" precision="day" value="${new Date()}"  /><br/>
<h2>Format</h2>
<g:radio name="feedType" value="RSS1" checked="true"/><span>RSS 1.0</span>
<g:radio name="feedType" value="RSS2"/><span>RSS 2.0</span>
<g:radio name="feedType" value="ATOM"/><span>Atom</span><br/>
<hr />
<h2>Topics</h2>
<g:each in="${list}" var="subscription" status="i">
  <g:if test="${i == 0}">
    <g:radio name="nodeID" value="subscription.name" checked="true"/><span>${subscription.getPrettyName()}</span><br/>
  </g:if>
  <g:else>
    <g:radio name="nodeID" value="${subscription.name}"/><span>${subscription.getPrettyName()}</span><br/>
  </g:else>
</g:each>
<hr/>
<g:submitButton name="getFeedButton" value="Get Feed!" />

从控制器:

def show = {
    def nodeID = params.nodeID
    def feedType
    if(params.feedType.equals("RSS1")){
        feedType = FeedType.RSS1;
    } else if(params.feedType.equals("RSS2")){
        feedType = FeedType.RSS2;
    } else{
        feedType = FeedType.ATOM;
    }
    def date = params.startDate
    println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
    println(date)
    println("Time "+System.currentTimeMillis());
    println("****************************")
    def feed = XMPPListenerService.getFeed(date, feedType, nodeID)
    response.contentType = "text/xml"
    response.outputStream << feed;
}

输出:

美国东部时间1994年9月17日星期六00:00:00

****************************
!!!!!!!!!!!!!!!!!!!!!!!!!!!!
无效的


2010-09-17 17 17:05:44100[http-8080-2]错误errors.grailExceptionResolver-空
java.lang.NullPointerException