A Simple Apllication with DWR:
DWR: Direct Web Remoting-Easy Ajax for java
Link for DWR tutorial and download is:
http://directwebremoting.org/dwr/index.html
I found it very useful for my project PMS(Project Management System).
That's why I would like to demonstrate a simple application.
Just create webproject and put dwr.jar into lib.
Make changes in web.xml:
"<servlet>
<servlet-name>dwr-invoker</servlet-name>
<servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
<init-param>
<param-name>debug</param-name>
<param-value>true</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>dwr-invoker</servlet-name>
<url-pattern>/dwr/*</url-pattern>
</servlet-mapping>"
create dwr.xml and put following entries
"<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dwr PUBLIC "-//GetAhead Limited//DTD Direct Web Remoting 0.4//EN" "http://www.getahead.ltd.uk/dwr/dwr.dtd">
<dwr>
<allow>
<create creator="new" javascript="DwrDemo">
<param name="class" value="deep.DwrDemo"/>
</create>
</allow>
</dwr>"
value of class where you write your fuction which you want to call on any event.
and this javascript (Here DwrDemo) willbe created corresponding to that class.
Now we try to use it in a simple JSP page.
Add these lines in you JSP.
" <script type='text/javascript' src='dwr/engine.js'></script>
<script type='text/javascript' src='dwr/util.js'></script>
<!-- This JavaScript file is generated specifically for your application -->
<script type='text/javascript' src='dwr/interface/DwrDemo.js'></script>
<script type="text/javascript">
function demo() {
var name = DWRUtil.getValue("name");
DwrDemo.demo(name,function(val)
{
DWRUtil.setValue("first",val);
}
);
}
</script>
This javascript function calls demo() method which is inside DwrDemo method.
val is value which is returned by function demo().
<body>
<select id="name" name="name" onchange="demo();">
<option value="Deepak">Deepak</option>
<option value="Anil">Anil</option>
<option value="Akash">Akash</option>
<option value="Mayank">Mayank</option>
</select>
<input type="text" id="first"/>
</body> "
Class deep.DwrDemo is given below.
package deep;
public class DwrDemo {
public String demo(String name)
{
if(name.equals("Deepak"))
return "Hello "+name+" Pandey";
else
return "Hello "+name;
}
}
Now Run your application.
