## Uses of Interface
org.springframework.messaging.MessageHandler

Packages that use MessageHandler
org.springframework.messaging: Support for working with messaging APIs and protocols.
org.springframework.messaging.handler.invocation: Common infrastructure for invoking message handler methods.
org.springframework.messaging.simp.annotation.support: Support classes for handling messages from simple messaging protocols (like STOMP).
org.springframework.messaging.simp.broker: Provides a "simple" message broker implementation along with an abstract base class and other supporting types such as a registry for subscriptions.
org.springframework.messaging.simp.config: Configuration support for WebSocket messaging using higher level messaging protocols.
org.springframework.messaging.simp.stomp: Generic support for simple messaging protocols (like STOMP).
org.springframework.messaging.simp.user: Support for handling messages to "user" destinations (i.e.
org.springframework.messaging.support: Provides implementations of `Message` along with a MessageBuilder and MessageHeaderAccessor for building and working with messages and message headers, as well as various `MessageChannel` implementations and channel interceptor support.

### Uses of MessageHandler in org.springframework.messaging

Methods in org.springframework.messaging with parameters of type MessageHandler
`boolean` SubscribableChannel.`subscribe(MessageHandler handler)` Register a message handler.
`boolean` SubscribableChannel.`unsubscribe(MessageHandler handler)` Un-register a message handler.

### Uses of MessageHandler in org.springframework.messaging.handler.invocation

Classes in org.springframework.messaging.handler.invocation that implement MessageHandler
`class` `AbstractMethodMessageHandler<T>` Abstract base class for HandlerMethod-based message handling.

### Uses of MessageHandler in org.springframework.messaging.simp.annotation.support

Classes in org.springframework.messaging.simp.annotation.support that implement MessageHandler
`class` `SimpAnnotationMethodMessageHandler` A handler for messages delegating to `@MessageMapping` and `@SubscribeMapping` annotated methods.

### Uses of MessageHandler in org.springframework.messaging.simp.broker

Classes in org.springframework.messaging.simp.broker that implement MessageHandler
`class` `AbstractBrokerMessageHandler` Abstract base class for a `MessageHandler` that broker messages to registered subscribers.
`class` `SimpleBrokerMessageHandler` A "simple" message broker that recognizes the message types defined in `SimpMessageType`, keeps track of subscriptions with the help of a `SubscriptionRegistry` and sends messages to subscribers.

### Uses of MessageHandler in org.springframework.messaging.simp.config

Methods in org.springframework.messaging.simp.config that return MessageHandler
`MessageHandler` AbstractMessageBrokerConfiguration.`userRegistryMessageHandler()`

### Uses of MessageHandler in org.springframework.messaging.simp.stomp

Classes in org.springframework.messaging.simp.stomp that implement MessageHandler
`class` `StompBrokerRelayMessageHandler` A `MessageHandler` that handles messages by forwarding them to a STOMP broker.

Methods in org.springframework.messaging.simp.stomp that return types with arguments of type MessageHandler
`Map<String,MessageHandler>` StompBrokerRelayMessageHandler.`getSystemSubscriptions()` Return the configured map with subscriptions on the "system" connection.

Method parameters in org.springframework.messaging.simp.stomp with type arguments of type MessageHandler
`void` StompBrokerRelayMessageHandler.`setSystemSubscriptions(Map<String,MessageHandler> subscriptions)` Configure one more destinations to subscribe to on the shared "system" connection along with MessageHandler's to handle received messages.

### Uses of MessageHandler in org.springframework.messaging.simp.user

Classes in org.springframework.messaging.simp.user that implement MessageHandler
`class` `UserDestinationMessageHandler` `MessageHandler` with support for "user" destinations.
`class` `UserRegistryMessageHandler` `MessageHandler` that handles user registry broadcasts from other application servers and periodically broadcasts the content of the local user registry.

### Uses of MessageHandler in org.springframework.messaging.support

Methods in org.springframework.messaging.support that return MessageHandler
`MessageHandler` MessageHandlingRunnable.`getMessageHandler()` Return the MessageHandler that will be used to handle the message.

Methods in org.springframework.messaging.support that return types with arguments of type MessageHandler
`Set<MessageHandler>` AbstractSubscribableChannel.`getSubscribers()`

Methods in org.springframework.messaging.support with parameters of type MessageHandler
`default void` ExecutorChannelInterceptor.`afterMessageHandled(Message<?> message, MessageChannel channel, MessageHandler handler, Exception ex)` Invoked inside the `Runnable` submitted to the Executor after calling the target MessageHandler regardless of the outcome (i.e.
`default Message<?>` ExecutorChannelInterceptor.`beforeHandle(Message<?> message, MessageChannel channel, MessageHandler handler)` Invoked inside the `Runnable` submitted to the Executor just before calling the target MessageHandler to handle the message.
`boolean` AbstractSubscribableChannel.`hasSubscription(MessageHandler handler)`
`boolean` AbstractSubscribableChannel.`subscribe(MessageHandler handler)`
`boolean` AbstractSubscribableChannel.`unsubscribe(MessageHandler handler)`