问题
I can't find a useful example for polling a JPA source for inbound data. I know how to do this in XML but can't figure out how do it in DSL.
In short what I want to do is periodically poll a JPA repository for records then put the records into a flow that will do the usual filtering/transforming/executing.
Kind regards
David Smith
回答1:
Wire up a JpaPollingChannelAdapter
as a @Bean
and use
IntegrationFlows.from(jpaMessageSource(),
c -> c.poller(Pollers.fixedDelay(1000)))
.transform(...)
...
See the DSL Reference for configuration options.
This one's near the top (with a different message source).
回答2:
You are right: there is no yet JPA components support in the Spring Integration Java DSL. Feel free to raise a JIRA (JavaDSL
component) on the matter and we'll take care about this demand. Feel free to contribute as well!
Meanwhile I can help you to figure out how to do that without high-level API.
The <int-jpa:inbound-channel-adapter>
is based on the JpaPollingChannelAdapter
and JpaExecutor
objects (exactly them we will use for DSL API). You just must to configure @Bean
for JpaExecutor
and use it like this:
@Bean
public JpaExecutor jpaExecutor(EntityManagerFactory entityManagerFactory) {
JpaExecutor jpaExecutor = new JpaExecutor(entityManagerFactory);
jpaExecutor.setJpaQuery("from Foo");
....
return jpaExecutor;
}
@Bean
public IntegrationFlow jpaFlow(JpaExecutor jpaExecutor) {
return IntegrationFlows.from(new JpaPollingChannelAdapter(jpaExecutor))
.split()
.transform()
....
}
Everything else will be done by framework as usual for existing DSL components API.
UPDATE
How to provide auto-startup= property when creating JpaPollingChannelAdapter programmatically? Also, is it possible to get this bean and invoke .start(), .stop() using control-bus?
See, Gary's answer. The Lifecycle
control is a responsibility of Endpoint
in our case it is SourcePollingChannelAdapter
. So, you should specify that second Lambda argument, configure the .autoStartup()
and .id()
there to be able to inject the SourcePollingChannelAdapter
for your JpaPollingChannelAdapter
and operate with it for your purpose. That id
really can be used from control-bus
to start()/stop()
at runtime.
Yes, I agree JpaPollingChannelAdapter
is unfortunate name for that class because it is really a MessageSource
implementation.
来源:https://stackoverflow.com/questions/30799031/example-spring-integration-dsl-for-jpa-inbound-channel-adapter