Spring Integration provides a generic router. You can use it for general-purpose routing (as opposed to the other routers provided by Spring Integration, each of which has some form of specialization).
The following section explains a router configuration with an XML components.
The router element provides a way to connect a router to an input channel and also accepts the optional default-output-channel attribute.
The ref attribute references the bean name of a custom router implementation (which must extend AbstractMessageRouter).
The following example shows three generic routers:
<int:router ref="payloadTypeRouter" input-channel="input1"
default-output-channel="defaultOutput1"/>
<int:router ref="recipientListRouter" input-channel="input2"
default-output-channel="defaultOutput2"/>
<int:router ref="customRouter" input-channel="input3"
default-output-channel="defaultOutput3"/>
<beans:bean id="customRouterBean" class="org.foo.MyCustomRouter"/>Alternatively, ref may point to a POJO that contains the @Router annotation (shown later), or you can combine the ref with an explicit method name.
Specifying a method applies the same behavior described in the @Router annotation section, later in this document.
The following example defines a router that points to a POJO in its ref attribute:
<int:router input-channel="input" ref="somePojo" method="someMethod"/>We generally recommend using a ref attribute if the custom router implementation is referenced in other <router> definitions.
However, if the custom router implementation should be scoped to a single definition of the <router>, you can provide an inner bean definition, as the following example shows:
<int:router method="someMethod" input-channel="input3"
default-output-channel="defaultOutput3">
<beans:bean class="org.foo.MyCustomRouter"/>
</int:router>
Using both the ref attribute and an inner handler definition in the same <router> configuration is not allowed.
Doing so creates an ambiguous condition and throws an exception.
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Using both the ref attribute and an inner handler definition in the same <router> configuration is not allowed.
Doing so creates an ambiguous condition and throws an exception.
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If the ref attribute references a bean that extends AbstractMessageProducingHandler (such as routers provided by the framework itself), the configuration is optimized to reference the router directly.
In this case, each ref attribute must refer to a separate bean instance (or a prototype-scoped bean) or use the inner <bean/> configuration type.
However, this optimization applies only if you do not provide any router-specific attributes in the router XML definition.
If you inadvertently reference the same message handler from multiple beans, you get a configuration exception.
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If the ref attribute references a bean that extends AbstractMessageProducingHandler (such as routers provided by the framework itself), the configuration is optimized to reference the router directly.
In this case, each ref attribute must refer to a separate bean instance (or a prototype-scoped bean) or use the inner <bean/> configuration type.
However, this optimization applies only if you do not provide any router-specific attributes in the router XML definition.
If you inadvertently reference the same message handler from multiple beans, you get a configuration exception.
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The following example shows the equivalent router configured in Java:
@Bean
@Router(inputChannel = "routingChannel")
public AbstractMessageRouter myCustomRouter() {
return new AbstractMessageRouter() {
@Override
protected Collection<MessageChannel> determineTargetChannels(Message<?> message) {
return // determine channel(s) for message
}
};
}The following example shows the equivalent router configured by using the Java DSL:
@Bean
public IntegrationFlow routerFlow() {
return IntegrationFlow.from("routingChannel")
.route(myCustomRouter())
.get();
}
public AbstractMessageRouter myCustomRouter() {
return new AbstractMessageRouter() {
@Override
protected Collection<MessageChannel> determineTargetChannels(Message<?> message) {
return // determine channel(s) for message
}
};
}Alternately, you can route on data from the message payload, as the following example shows:
@Bean
public IntegrationFlow routerFlow() {
return IntegrationFlow.from("routingChannel")
.route(String.class, p -> p.contains("foo") ? "fooChannel" : "barChannel")
.get();
}