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Configuring a Router with Annotations

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.

See also Message Routers in the Java DSL chapter for more information about router configuration.