org.springframework.cloud.stream.binder

Class PartitionHandler

java.lang.Object

org.springframework.cloud.stream.binder.PartitionHandler

public class PartitionHandler
extends Object

Utility class to determine if a binding is configured for partitioning (based on the binder properties provided in the constructor) and what partition a message should be delivered to.

Author:

Patrick Peralta, David Turanski, Gary Russell, Ilayaperumal Gopinathan, Mark Fisher, Marius Bogoevici

Constructor Summary

Constructors

Constructor and Description
PartitionHandler(org.springframework.expression.EvaluationContext evaluationContext, ProducerProperties properties, PartitionKeyExtractorStrategy partitionKeyExtractorStrategy, PartitionSelectorStrategy partitionSelectorStrategy) Construct a PartitionHandler.

Method Summary

Modifier and Type	Method and Description
int	determinePartition(org.springframework.messaging.Message<?> message) Determine the partition to which to send this message.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PartitionHandler

public PartitionHandler(org.springframework.expression.EvaluationContext evaluationContext,
                        ProducerProperties properties,
                        PartitionKeyExtractorStrategy partitionKeyExtractorStrategy,
                        PartitionSelectorStrategy partitionSelectorStrategy)

Construct a PartitionHandler.

Parameters:

evaluationContext - evaluation context for binder

properties - binder properties

partitionKeyExtractorStrategy - PartitionKeyExtractor strategy

partitionSelectorStrategy - PartitionSelector strategy

Method Detail

determinePartition

public int determinePartition(org.springframework.messaging.Message<?> message)

Determine the partition to which to send this message.

If a partition key extractor class is provided, it is invoked to determine the key. Otherwise, the partition key expression is evaluated to obtain the key value.

If a partition selector class is provided, it will be invoked to determine the partition. Otherwise, if the partition expression is not null, it is evaluated against the key and is expected to return an integer to which the modulo function will be applied, using the partitionCount as the divisor. If no partition expression is provided, the key will be passed to the binder partition strategy along with the partitionCount. The default partition strategy uses key.hashCode(), and the result will be the mod of that value.

Parameters:

message - the message.

Returns:

the partition