Package io.flutter.plugin.common

Class EventChannel

java.lang.Object

io.flutter.plugin.common.EventChannel

public final class EventChannel
extends Object

A named channel for communicating with the Flutter application using asynchronous event streams.

Incoming requests for event stream setup are decoded from binary on receipt, and Java responses and events are encoded into binary before being transmitted back to Flutter. The MethodCodec used must be compatible with the one used by the Flutter application. This can be achieved by creating an EventChannel counterpart of this channel on the Dart side. The Java type of stream configuration arguments, events, and error details is Object, but only values supported by the specified MethodCodec can be used.

The logical identity of the channel is given by its name. Identically named channels will interfere with each other's communication.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	EventChannel.EventSink	Event callback.
static interface	EventChannel.StreamHandler	Handler of stream setup and teardown requests.

Constructor Summary

Constructors

Constructor	Description
EventChannel(BinaryMessenger messenger, String name)	Creates a new channel associated with the specified BinaryMessenger and with the specified name and the standard MethodCodec.
EventChannel(BinaryMessenger messenger, String name, MethodCodec codec)	Creates a new channel associated with the specified BinaryMessenger and with the specified name and MethodCodec.
EventChannel(BinaryMessenger messenger, String name, MethodCodec codec, BinaryMessenger.TaskQueue taskQueue)	Creates a new channel associated with the specified BinaryMessenger and with the specified name and MethodCodec.

Method Summary

Modifier and Type	Method	Description
void	setStreamHandler(EventChannel.StreamHandler handler)	Registers a stream handler on this channel.

Methods inherited from class java.lang.Object

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

Constructor Details

EventChannel

public EventChannel(BinaryMessenger messenger,
 String name)

Creates a new channel associated with the specified BinaryMessenger and with the specified name and the standard MethodCodec.

Parameters:

messenger - a BinaryMessenger.

name - a channel name String.

EventChannel

public EventChannel(BinaryMessenger messenger,
 String name,
 MethodCodec codec)

Creates a new channel associated with the specified BinaryMessenger and with the specified name and MethodCodec.

Parameters:

messenger - a BinaryMessenger.

name - a channel name String.

codec - a MessageCodec.

EventChannel

public EventChannel(BinaryMessenger messenger,
 String name,
 MethodCodec codec,
 BinaryMessenger.TaskQueue taskQueue)

Creates a new channel associated with the specified BinaryMessenger and with the specified name and MethodCodec.

Parameters:

messenger - a BinaryMessenger.

name - a channel name String.

codec - a MessageCodec.

taskQueue - a BinaryMessenger.TaskQueue that specifies what thread will execute the handler. Specifying null means execute on the platform thread. See also BinaryMessenger.makeBackgroundTaskQueue().

Method Details

setStreamHandler

@UiThread
public void setStreamHandler(EventChannel.StreamHandler handler)

Registers a stream handler on this channel.

Overrides any existing handler registration for (the name of) this channel.

If no handler has been registered, any incoming stream setup requests will be handled silently by providing an empty stream.

Parameters:

handler - a EventChannel.StreamHandler, or null to deregister.