Applet JavaScript通信

Question

On my web page I am running an applet and in order to warn user for certain inputs to the applet, I am using printing the errors to the html page. In order to do this I am using javascript applet communication. Below is the code for the Javascript:

<script type="text/javascript">
var counter=0;

function RemoveAppletErrorMessage()
{
    var AppletErrorTag=document.getElementById("AppletErrorMessages");
    if(AppletErrorTag!=null)
    {
        document.body.removeChild(AppletErrorTag);
    }
}

function updateWebPage(s)
{
    if(counter>=1) RemoveAppletErrorMessage();
    var parag=document.createElement('P');
    parag.setAttribute("id","AppletErrorMessages");
    var txt=document.createTextNode(s);
    parag.appendChild(txt);
    document.body.appendChild(parag);
    counter++;
}
</script>

Here, the Javascript function updateWebPage(s) function is called from the Java applet when a JButton is clicked with the following code:

if(jso != null && !errorMessage.isEmpty())
try {
    jso.call("updateWebPage", new String[] {errorMessage});
    return;
}
catch (Exception ex) { ex.printStackTrace(); }

In terms of communication everything works fine. However, when the JButton is clicked the second time, I am trying to clear up the error messages with RemoveAppletErrorMessage() calling from updateWebPage(s). It seems like every time I hit the JButton the error messages are appended to the web page which I do not want. I have tried to clear it with .innerHTML='' which did not work in the first place, so I changed my strategy to adding a node and checking if the node exists, clearing that node and adding again. What might be going on wrong?

Answer 1

I'd open a div with an id of AppletErrorMessages and use jQuery in my updateWebPage() function like this (eg stop creating a new paragraph every time).

function updateWebPage(s)
{
  $("#AppletErrorMessages").html(s);
}

Answer 2

可能是您在Java中附加了errorMessage变量？