[Openfire plug-in Development] iqhandler processes IQ request packets (template method mode)

Original link: http://www.hechunchen.info /? P = 15

 

We know that openfire plug-in development mainly involves three registration methods: 1) iqhandler (IQ handlers respond to IQ packets with a participant element name and namespace), 2) interceptor (packetinterceptor to receive all packets being send through the system and optionally reject them), 3) component (components receive all packets addressed to a participant sub-domain ).

Today, iqhandler is involved in a design pattern-the template method pattern.

The most iconic feature of the template method is that it requires an abstract class. In Java design patterns, abstract classes are rarely used, and interfaces are more used.

If we want to process our IQ package, we can customize classes such as testtemplatemethodhandler: Class testtemplatemethodhandler extends iqhandler, and then in public iqhandlerinfo getinfo () enter the name and namespace of the element you want to register in the method. In public IQ handleriq (IQ packet) in the method, write the information about the IQ package you want to perform (note that the IQ package is based on the Q & A format, so reply of the IQ package should be included ).

Sample Code:

 1 import org.jivesoftware.openfire.IQHandlerInfo;
 2 import org.jivesoftware.openfire.auth.UnauthorizedException;
 3 import org.jivesoftware.openfire.handler.IQHandler;
 4 import org.xmpp.packet.IQ;
 5 
 6 public class TestTemplateMethodHandler extends IQHandler
 7 {
 8     private IQHandlerInfo info;
 9     
10     public TestTemplateMethodHandler()
11     {
12         super("TestTemplateMethodHandler");
13         info = new IQHandlerInfo("query", "http://hechunchen.info/querytest");
14     }
15     @Override
16     public IQHandlerInfo getInfo()
17     {
18         // TODO Auto-generated method stub
19         return info;
20     }
21 
22     @Override
23     public IQ handleIQ(IQ packet) throws UnauthorizedException
24     {
25         // TODO Auto-generated method stub
26         IQ reply = IQ.createResultIQ(packet);
27         System.out.println("iq from:" + reply.getFrom());
28         System.out.println("iq to:" + reply.getTo());
29         return reply;
30     }
31 }

 

Note that other methods of the parent class must call the abstract method. Otherwise, the subclass Writing Method (small details of the algorithm) is not used at all. For example, the handleriq method is called in void process (packet) in iqhandler.

To sum up, openfire uses the template method mode very well. The template method mode is very suitable for systems that may perform secondary development. We have defined a large Algorithm Framework in the parent class, and can postpone the determination of some small details to the subclass for implementation. Just like iqhandler has already written a big Algorithm Framework. After the second developer just needs extends iqhandler, he writes two methods to implement it and process the missing IQ package. We don't have to worry about how IQ packets are routed to us. Obviously, the template method reduces the difficulty of secondary development.