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GH-3558: Kotlin DSL: propagate generics info (#3561)

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Fixes https://github.com/spring-projects/spring-integration/issues/3558

Kotlin lambdas mostly used to configure endpoints in DSL manner
are not really Java lambdas, but rather anonymous classes implementing
respective Java interfaces.

While in most cases such classes carry generic info for their method impls
properly in Java, it is somehow doesn't work well for `GenericHandler`
implemented by Kotlin lambdas

* Wrap provided `GenericHandler` in the `BaseIntegrationFlowDefinition.handle()`
into a Java lambda and call `handle()` recursively to carry an expected type to
the `LambdaMessageProcessor`
* Fix `LambdaMessageProcessor` to handle `ClassUtils.isKotlinUnit()` result of
an invocation as a `null` reply

**Cherry-pick to `5.4.x` & `5.3.x`**
This commit is contained in:
Artem Bilan
2021-05-05 15:55:42 -04:00
committed by Gary Russell
parent 7aaef1e9ae
commit d5ff74b272
3 changed files with 11 additions and 4 deletions
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3
spring-integration-core/src/main/java/org/springframework/integration/dsl/BaseIntegrationFlowDefinition.java
View File

@@ -1046,6 +1046,9 @@ public abstract class BaseIntegrationFlowDefinition<B extends BaseIntegrationFlo
if (ClassUtils.isLambda(handler.getClass())) {
serviceActivatingHandler = new ServiceActivatingHandler(new LambdaMessageProcessor(handler, payloadType));
}
else if (payloadType != null) {
return handle(payloadType, handler::handle, endpointConfigurer);
}
else {
serviceActivatingHandler = new ServiceActivatingHandler(handler, ClassUtils.HANDLER_HANDLE_METHOD);
}

6
spring-integration-core/src/main/java/org/springframework/integration/handler/LambdaMessageProcessor.java
View File

@@ -94,7 +94,11 @@ public class LambdaMessageProcessor implements MessageProcessor<Object>, BeanFac
Object[] args = buildArgs(message);
try {
return this.method.invoke(this.target, args);
Object result = this.method.invoke(this.target, args);
if (result != null && org.springframework.integration.util.ClassUtils.isKotlinUnit(result.getClass())) {
result = null;
}
return result;
}
catch (InvocationTargetException e) {
if (e.getTargetException() instanceof ClassCastException) {

6
spring-integration-core/src/test/kotlin/org/springframework/integration/dsl/KotlinDslTests.kt
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2020 the original author or authors.
* Copyright 2020-2021 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -212,8 +212,8 @@ class KotlinDslTests {
fun `no reply from handle`() {
val payloadReference = AtomicReference<String>()
val integrationFlow =
integrationFlow("handlerInputChanenl") {
handle<String> { payload, _ -> payloadReference.set(payload) }
integrationFlow("handlerInputChannel") {
handle<Message<String>> { message, _ -> payloadReference.set(message.payload) }
}
val registration = this.integrationFlowContext.registration(integrationFlow).register()