When using @Router to annotate a method, the method may return either a MessageChannel or a String type.
In the latter case, the endpoint resolves the channel name as it does for the default output channel.
Additionally, the method may return either a single value or a collection.
If a collection is returned, the reply message is sent to multiple channels.
To summarize, the following method signatures are all valid:
@Router
public MessageChannel route(Message message) {...}
@Router
public List<MessageChannel> route(Message message) {...}
@Router
public String route(Foo payload) {...}
@Router
public List<String> route(Foo payload) {...}In addition to payload-based routing, a message may be routed based on metadata available within the message header as either a property or an attribute.
In this case, a method annotated with @Router may include a parameter annotated with @Header, which is mapped to a header value as the following example shows and documented in Annotation Support:
@Router
public List<String> route(@Header("orderStatus") OrderStatus status)| For routing of XML-based Messages, including XPath support, see XML Support - Dealing with XML Payloads. |
| For routing of XML-based Messages, including XPath support, see XML Support - Dealing with XML Payloads. |
See also Message Routers in the Java DSL chapter for more information about router configuration.