Package io.flutter.plugin.common

Interface BinaryMessenger

All Known Implementing Classes:

DartExecutor, FlutterNativeView, FlutterView

public interface BinaryMessenger

Facility for communicating with Flutter using asynchronous message passing with binary messages. The Flutter Dart code should use BinaryMessages to participate.

BinaryMessenger is expected to be utilized from a single thread throughout the duration of its existence. If created on the main thread, then all invocations should take place on the main thread. If created on a background thread, then all invocations should take place on that background thread.

See Also:

, which supports message passing with Strings and semi-structured messages., , which supports communication using asynchronous method invocation., , which supports communication using event streams.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	BinaryMessenger.BinaryMessageHandler	Handler for incoming binary messages from Flutter.
static interface	BinaryMessenger.BinaryReply	Binary message reply callback.
static interface	BinaryMessenger.TaskQueue	An abstraction over the threading policy used to invoke message handlers.
static class	BinaryMessenger.TaskQueueOptions	Options that control how a TaskQueue should operate and be created.

Method Summary

Modifier and Type	Method	Description
default void	disableBufferingIncomingMessages()	Disables the ability to queue messages received from Dart.
default void	enableBufferingIncomingMessages()	Enables the ability to queue messages received from Dart.
default BinaryMessenger.TaskQueue	makeBackgroundTaskQueue()	Creates a TaskQueue that executes the tasks serially on a background thread.
default BinaryMessenger.TaskQueue	makeBackgroundTaskQueue(BinaryMessenger.TaskQueueOptions options)	Creates a TaskQueue that executes the tasks serially on a background thread.
void	send(String channel, ByteBuffer message)	Sends a binary message to the Flutter application.
void	send(String channel, ByteBuffer message, BinaryMessenger.BinaryReply callback)	Sends a binary message to the Flutter application, optionally expecting a reply.
void	setMessageHandler(String channel, BinaryMessenger.BinaryMessageHandler handler)	Registers a handler to be invoked when the Flutter application sends a message to its host platform.
default void	setMessageHandler(String channel, BinaryMessenger.BinaryMessageHandler handler, BinaryMessenger.TaskQueue taskQueue)	Registers a handler to be invoked when the Flutter application sends a message to its host platform.

Method Detail

makeBackgroundTaskQueue

@UiThread
default BinaryMessenger.TaskQueue makeBackgroundTaskQueue()

Creates a TaskQueue that executes the tasks serially on a background thread.

There is no guarantee that the tasks will execute on the same thread, just that execution is serial. This is could be problematic if your code relies on ThreadLocal storage or introspection about what thread is actually executing.

makeBackgroundTaskQueue

@UiThread
default BinaryMessenger.TaskQueue makeBackgroundTaskQueue(BinaryMessenger.TaskQueueOptions options)

Creates a TaskQueue that executes the tasks serially on a background thread.

BinaryMessenger.TaskQueueOptions can be used to configure the task queue to execute tasks concurrently. Doing so can be more performant, though users need to ensure that the task handlers are thread-safe.

send

@UiThread
void send(@NonNull
          String channel,
          @Nullable
          ByteBuffer message)

Sends a binary message to the Flutter application.

Parameters:

channel - the name String of the logical channel used for the message.

message - the message payload, a direct-allocated ByteBuffer with the message bytes between position zero and current position, or null.

send

@UiThread
void send(@NonNull
          String channel,
          @Nullable
          ByteBuffer message,
          @Nullable
          BinaryMessenger.BinaryReply callback)

Sends a binary message to the Flutter application, optionally expecting a reply.

Any uncaught exception thrown by the reply callback will be caught and logged.

Parameters:

channel - the name String of the logical channel used for the message.

message - the message payload, a direct-allocated ByteBuffer with the message bytes between position zero and current position, or null.

callback - a BinaryMessenger.BinaryReply callback invoked when the Flutter application responds to the message, possibly null.

setMessageHandler

@UiThread
void setMessageHandler(@NonNull
                       String channel,
                       @Nullable
                       BinaryMessenger.BinaryMessageHandler handler)

Registers a handler to be invoked when the Flutter application sends a message to its host platform.

Registration overwrites any previous registration for the same channel name. Use a null handler to deregister.

If no handler has been registered for a particular channel, any incoming message on that channel will be handled silently by sending a null reply.

Parameters:

channel - the name String of the channel.

handler - a BinaryMessenger.BinaryMessageHandler to be invoked on incoming messages, or null.

setMessageHandler

@UiThread
default void setMessageHandler(@NonNull
                               String channel,
                               @Nullable
                               BinaryMessenger.BinaryMessageHandler handler,
                               @Nullable
                               BinaryMessenger.TaskQueue taskQueue)

Registers a handler to be invoked when the Flutter application sends a message to its host platform.

Registration overwrites any previous registration for the same channel name. Use a null handler to deregister.

If no handler has been registered for a particular channel, any incoming message on that channel will be handled silently by sending a null reply.

Parameters:

channel - the name String of the channel.

handler - a BinaryMessenger.BinaryMessageHandler to be invoked on incoming messages, or null.

taskQueue - a BinaryMessenger.TaskQueue that specifies what thread will execute the handler. Specifying null means execute on the platform thread.

enableBufferingIncomingMessages

default void enableBufferingIncomingMessages()

Enables the ability to queue messages received from Dart.

This is useful when there are pending channel handler registrations. For example, Dart may be initialized concurrently, and prior to the registration of the channel handlers. This implies that Dart may start sending messages while plugins are being registered.

disableBufferingIncomingMessages

default void disableBufferingIncomingMessages()

Disables the ability to queue messages received from Dart.

This can be used after all pending channel handlers have been registered.