net.engio.mbassy.listener

Interface IMessageFilter<M>

All Known Implementing Classes:

ElFilter, Filters.RejectSubtypes, Filters.SubtypesOnly

public interface IMessageFilter<M>

Message filters can be used to control what messages are delivered to a specific message handler. Filters are attached to message handler using the @Handler annotation. If a message handler specifies filters, the filters accepts(...) method will be checked before the actual handler is invoked. The handler will be invoked only if each filter accepted the message. Example:

 
  @Listener
  @Filters(Urlfilter.class)
 public void someHandler(String message){...}

 class Urlfilter implements IMessageFilter{
     public boolean accepts(String message, SubscriptionContext context){
         return message.startsWith("http");
     }
 }

 bus.post("http://www.infoq.com"); // will be delivered
 bus.post("www.stackoverflow.com"); // will not be delivered

 
 

NOTE: A message filter must provide a no-arg constructor!!!

Author:

bennidi Date: 2/8/12

Method Summary

Modifier and Type	Method and Description
boolean	accepts(M message, SubscriptionContext context) Check whether the message matches some criteria

Method Detail

accepts

boolean accepts(M message,
                SubscriptionContext context)

Check whether the message matches some criteria

Parameters:

message - The message to be handled by the handler

context - The context object containing a description of the message handler and the bus environment

Returns:

true: if the message matches the criteria and should be delivered to the handler false: otherwise