我如何在Scriplets中使用javascript var

Question

I am trying to learn jsp. I know a little bit java and I dont know much about html tags so I simple use java codes as much as I can. What I am trying to do there is getting data from variables from text boxes and using them as string.

var text1 =<% request.getParameter("locationId"); %>;

<%
if ((text1 != null && text2 != null) && (!text1.equals("") && !text2.equals(""))) {
        kw1 = "'%"+text1+"%'";
        kw2 = "'%"+text2+"%'";
.
.
.
}
%>

Answer 1

Scriptlet is executed before any data about webpage get sent from server to client. Whatever you want to do you need to send postback to server (with forms or ajax call). I usually use jQuery so my answer will use it but feel free to modify it to use native JS code. First, I would create a page on server called something like createJsonObject , call it from client with $.ajax (type: "POST") and passed my argument as object

{varID: varID}

On server I would place my JSP on that page, read argumants upon page load, execute function and return object with data to client. In .done() I would do something with that data (display them in form, save them in JS variables...).

Hope this helps you out.

Example (Just showing how you can use Ajax with form example)

HTML form:

<form name="formName" method="post" action="">
 <input type="text" name="name" id="firstName" value="" />
 <input type="text" name="lastName" id="lastName" value="" />
 <input type="submit" name="Update" id="update" value="Update" />
</form>

Ajax Post:

$("#update").click(function(e) 
{
   e.preventDefault();
   var firstName = $("#firstName").val(); 
   var lastName = $("#lastName").val();
   var dataObject = {};
   dataObject.firstName = firstName;
   dataObject.lastName = lastName;

   $.ajax({
       type:'POST',
       data:dataObject,
       url:'returnData.php',
       success:function(data) 
       {
         alert(data);
       }
   });
});

PHP:

<?php
  $receivedObject = json_decode($_POST['data'], true);
  $name = $receivedObject['firstName'];
  $lastName = $receivedObject['lastName'];
  echo $name . ' ' . $lastName;
?>

I've not test this, so there might be somewhere i've gone wrong. But try something like my example and just ask if you need any help.

Answer 2

Ali, you can not use a javascript variable into jsp scriplate.

<%

String locationId=request.getParameter("locationId"); 

if ((text1 != null && text2 != null) && (!text1.equals("") && !text2.equals(""))) {
        kw1 = "'%"+text1+"%'";
        kw2 = "'%"+text2+"%'";
.
.
.
}
%>

but vise versa is possible you can use JSP variable into you javascript code.like this.

<script>
    var locationId='<%=request.getParameter("locationId")%>';
    alert(locationId);
</script>