GH-317: Add Static Routing Key

Resolves https://github.com/spring-cloud/spring-cloud-stream-binder-rabbit/issues/317

GH-317 Adding static routing key field to producer properties

GH-317 Updating based on PR comments

GH-317 Updating import order based on checkstyle

GH-317 Updating import order based on checkstyle

README.adoc

@@ -889,9 +889,13 @@ Applies only when `requiredGroups` are provided and then only to those groups.
 Default: none - broker default will apply.
 routingKeyExpression::
 A SpEL expression to determine the routing key to use when publishing messages.
-For a fixed routing key, use a literal expression, such as `routingKeyExpression='my.routingKey'` in a properties file or `routingKeyExpression: '''my.routingKey'''` in a YAML file.
+For a fixed routing key, use `routingKey`.
 +
 Default: `destination` or `destination-<partition>` for partitioned destinations.
+routingKey::
+A string defining a fixed routing key to use when publishing messages.
++
+Default: see `routingKeyExpression`
 singleActiveConsumer::
 Set to true to set the `x-single-active-consumer` queue property to true.
 Applies only when `requiredGroups` are provided and then only to those groups.

docs/src/main/asciidoc/overview.adoc

@@ -928,9 +928,13 @@ Applies only when `requiredGroups` are provided and then only to those groups.
 Default: none - broker default will apply.
 routingKeyExpression::
 A SpEL expression to determine the routing key to use when publishing messages.
-For a fixed routing key, use a literal expression, such as `routingKeyExpression='my.routingKey'` in a properties file or `routingKeyExpression: '''my.routingKey'''` in a YAML file.
+For a fixed routing key, use `routingKey`.
 +
 Default: `destination` or `destination-<partition>` for partitioned destinations.
+routingKey::
+A string defining a fixed routing key to use when publishing messages.
++
+Default: see `routingKeyExpression`
 singleActiveConsumer::
 Set to true to set the `x-single-active-consumer` queue property to true.
 Applies only when `requiredGroups` are provided and then only to those groups.

spring-cloud-stream-binder-rabbit-core/src/main/java/org/springframework/cloud/stream/binder/rabbit/properties/RabbitProducerProperties.java

@@ -16,12 +16,17 @@
 
 package org.springframework.cloud.stream.binder.rabbit.properties;
 
+import java.util.Optional;
+
 import jakarta.validation.constraints.Min;
 
 import org.springframework.amqp.core.MessageDeliveryMode;
 import org.springframework.expression.Expression;
+import org.springframework.expression.common.LiteralExpression;
 import org.springframework.util.Assert;
 
+
+
 /**
  * @author Marius Bogoevici
  * @author Gary Russell
@@ -102,6 +107,12 @@ public class RabbitProducerProperties extends RabbitCommonProperties {
 	 */
 	private Expression delayExpression;
 
+	/**
+	 * a static routing key when publishing messages; default is the destination name;
+	 * suffixed by "-partition" when partitioned. This is only used if `routingKeyExpression` is null
+	 */
+	private String routingKey;
+
 	/**
 	 * a custom routing key when publishing messages; default is the destination name;
 	 * suffixed by "-partition" when partitioned.
@@ -232,13 +243,24 @@ public class RabbitProducerProperties extends RabbitCommonProperties {
 	}
 
 	public Expression getRoutingKeyExpression() {
-		return this.routingKeyExpression;
+		return Optional.ofNullable(this.routingKeyExpression)
+				.orElseGet(() -> Optional.ofNullable(this.routingKey)
+						.map(LiteralExpression::new)
+						.orElse(null));
 	}
 
 	public void setRoutingKeyExpression(Expression routingKeyExpression) {
 		this.routingKeyExpression = routingKeyExpression;
 	}
 
+	public String getRoutingKey() {
+		return this.routingKey;
+	}
+
+	public void setRoutingKey(String routingKey) {
+		this.routingKey = routingKey;
+	}
+
 	public String getConfirmAckChannel() {
 		return this.confirmAckChannel;
 	}

spring-cloud-stream-binder-rabbit/src/test/java/org/springframework/cloud/stream/binder/rabbit/RabbitBinderTests.java

@@ -2064,6 +2064,38 @@ public class RabbitBinderTests extends
 		producerBinding.unbind();
 	}
 
+	@Test
+	public void testRoutingKey(TestInfo testInfo) throws Exception {
+		String routingKey = "static.key";
+		RabbitTestBinder binder = getBinder();
+		ExtendedProducerProperties<RabbitProducerProperties> producerProperties = createProducerProperties(testInfo);
+		producerProperties.getExtension().setRoutingKey(routingKey);
+
+		DirectChannel output = createBindableChannel("output",
+				createProducerBindingProperties(producerProperties));
+		output.setBeanName("rkeProducer");
+		Binding<MessageChannel> producerBinding = binder.bindProducer("rke", output,
+				producerProperties);
+
+		RabbitAdmin admin = new RabbitAdmin(this.rabbitAvailableRule.getResource());
+		Queue queue = new AnonymousQueue();
+		DirectExchange exchange = new DirectExchange("rke");
+		org.springframework.amqp.core.Binding binding = BindingBuilder.bind(queue)
+				.to(exchange).with(routingKey);
+		admin.declareQueue(queue);
+		admin.declareBinding(binding);
+
+		output.send(new GenericMessage<>(new Pojo("rkeTest")));
+
+		Object out = spyOn(queue.getName()).receive(false);
+		assertThat(out).isInstanceOf(byte[].class);
+		assertThat(new String((byte[]) out, StandardCharsets.UTF_8))
+				.isEqualTo("{\"field\":\"rkeTest\"}");
+
+
+		producerBinding.unbind();
+	}
+
 	@Test
 	public void testRoutingKeyExpressionPartitionedAndDelay(TestInfo testInfo) throws Exception {
 		RabbitTestBinder binder = getBinder();