DWR (http://getahead.ltd.uk/dwr/) is a new Ajax way, unlike the traditional mode of accessing URLs, DWR has made a Generic service Gateway (PROXY) at the server, making the client's Javascript can directly manipulate the service layer of the remote server side, and then cooperate with Trimpath Jstemplate to render the service layer Pojo as a complex page in template instead of Dom Builder. Create a new, pure AJAX programming model.
Today, DWR's application has been explained a lot, we can Google themselves. Here are only a few key points: standard installation and use, Trimpath jstemplate application, DWR2.0 push technology application.
Springside in the bookstore example of book management--cover image Ajax upload, using DWR to get the size of the uploaded part. 2. Installation and use 2.1 Download Dwr
The latest version of 2.0RC1 is on the official website, and sometimes the latest version needs to be downloaded to dwr.dev.java.net. 2.2 configuration Files
Modify Web.xml to add Dwr-invoker servlet
Add Dwr.xml, configure exported service services, and beans to convert to client JavaScript.
If the security requirements are not strict, can be very simple to match up, if Strictly a little trouble, see dwr.xml comments. 2.3 Client calls 1. Introduce DWR a dynamically generated JavaScript and two standard utils.js:
Bookservice.js's name is defined in the service-side dwr.xml.
2. Use the Bookservice object:Interface/bookservice.js "/>" type= "Text/javascript" > //-->
"/>" type= "Text/javascript" > //-->
"/>" type= "Text/javascript" > //-->
In the JavaScript that follows, you can use the Bookservice object and his methods like in Java, such as
Bookservice.findbooksbycategory (category, Drawbooks);
The first parameter is the server-side findbookbycategory parameter, and the 2nd parameter is the function to be processed when it is returned. 3. Using Trimpath jstemplate render the returned Pojo:
"/>" type= "Text/javascript" > //-->
Then according to trimpath similar freemarker simple syntax in the writing template and the JS Pojo into the template to render.
{for B in MyBooks}
<p>${b.name}</p>
{/for}
specific demo in 1.0m3 bookstore Front Webservcie page. 4. Push Technology
dwr2.0.x push Technology to push the message, applicable to the chatroom, stock information display and other scenarios, better than the current JS timer polling service-side strategy, greatly reduce the resources of the server (no change in the data does not need to answer the client's timing query). 4.1. Receive page for push message
Sets JavaScript to receive messages pushed over by the service side
1 <script type= ' text/javascript ' src= ' <c:url value= "/dwr/engine.js" > ' ></script>
<script type= ' text/javascript ' src= ' <c:url value= '/dwr/ Util.js "/> ' ></script>
<script type= ' text/javascript ' src= ' <c:url value= '" Dwr/interface/ordernotice.js "/> ' ></script>"
2. <script language= "JavaScript" >
function receivemessages (ID) {
$ (' Ordernotice '). InnerHTML = "Receive a new Order with ID + ID +"! ";
$ (' Ordernotice '). Show ();
}
</script>
3.<body onload= "Dwrengine.setreverseajax (true);"
<div id= "Ordernotice"/>
First, the introduction of DWR and the Java Class (Ordernotice), which is responsible for performing the push operation, JS
Second, write any of the JS function of receiving information
third, in the body of the onload set Reverseajax=true, start listening to information 4.2 Java classes responsible for pushing messages
public class Ordernotice {
public void noticeneworder (int id) { & nbsp; Webcontext wctx = Webcontextfactory.get ();
Scriptbuffer script = new Scriptbuffer ();
script.appendscript ("Receivemessages ("). AppendData ( ID). Appendscript (");
ServerContext sctx = Servercontextfactory.get ( Wctx.getservletcontext ());
Collection pages = sctx.getscriptsessionsbypage ("/springside/ Admin/top.jsp ");
for (scriptsession session:pages) {
session.addscript (script);
}
}
}
Visible, the first Scriptbuffer constructs a section of SQL executed on the client, calling the Receivemessages function of the previously received page.
then use Webcontext, ServerContext to locate the session that needs to be sent. Note Here hard code has a URL path to determine subscriber, or, as in chatroom, to send a session to the caller initiator on the same page as the Ordernotice. 4.3 remaining work
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