Class BasicMessageChannel<T>
- java.lang.Object
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- io.flutter.plugin.common.BasicMessageChannel<T>
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public final class BasicMessageChannel<T> extends Object
A named channel for communicating with the Flutter application using basic, asynchronous message passing.Messages are encoded into binary before being sent, and binary messages received are decoded into Java objects. The
MessageCodec
used must be compatible with the one used by the Flutter application. This can be achieved by creating a BasicMessageChannel counterpart of this channel on the Dart side. The static Java type of messages sent and received isObject
, but only values supported by the specifiedMessageCodec
can be used.The logical identity of the channel is given by its name. Identically named channels will interfere with each other's communication.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interface
BasicMessageChannel.MessageHandler<T>
A handler of incoming messages.static interface
BasicMessageChannel.Reply<T>
Message reply callback.
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Field Summary
Fields Modifier and Type Field Description static String
CHANNEL_BUFFERS_CHANNEL
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Constructor Summary
Constructors Constructor Description BasicMessageChannel(BinaryMessenger messenger, String name, MessageCodec<T> codec)
Creates a new channel associated with the specifiedBinaryMessenger
and with the specified name andMessageCodec
.BasicMessageChannel(BinaryMessenger messenger, String name, MessageCodec<T> codec, BinaryMessenger.TaskQueue taskQueue)
Creates a new channel associated with the specifiedBinaryMessenger
and with the specified name andMessageCodec
.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
resizeChannelBuffer(int newSize)
Adjusts the number of messages that will get buffered when sending messages to channels that aren't fully set up yet.void
send(T message)
Sends the specified message to the Flutter application on this channel.void
send(T message, BasicMessageChannel.Reply<T> callback)
Sends the specified message to the Flutter application, optionally expecting a reply.void
setMessageHandler(BasicMessageChannel.MessageHandler<T> handler)
Registers a message handler on this channel for receiving messages sent from the Flutter application.
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Field Detail
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CHANNEL_BUFFERS_CHANNEL
public static final String CHANNEL_BUFFERS_CHANNEL
- See Also:
- Constant Field Values
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Constructor Detail
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BasicMessageChannel
public BasicMessageChannel(@NonNull BinaryMessenger messenger, @NonNull String name, @NonNull MessageCodec<T> codec)
Creates a new channel associated with the specifiedBinaryMessenger
and with the specified name andMessageCodec
.- Parameters:
messenger
- aBinaryMessenger
.name
- a channel name String.codec
- aMessageCodec
.
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BasicMessageChannel
public BasicMessageChannel(@NonNull BinaryMessenger messenger, @NonNull String name, @NonNull MessageCodec<T> codec, BinaryMessenger.TaskQueue taskQueue)
Creates a new channel associated with the specifiedBinaryMessenger
and with the specified name andMessageCodec
.- Parameters:
messenger
- aBinaryMessenger
.name
- a channel name String.codec
- aMessageCodec
.taskQueue
- aBinaryMessenger.TaskQueue
that specifies what thread will execute the handler. Specifying null means execute on the platform thread. See alsoBinaryMessenger.makeBackgroundTaskQueue()
.
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Method Detail
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send
public void send(@Nullable T message)
Sends the specified message to the Flutter application on this channel.- Parameters:
message
- the message, possibly null.
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send
@UiThread public void send(@Nullable T message, @Nullable BasicMessageChannel.Reply<T> callback)
Sends the specified message to the Flutter application, optionally expecting a reply.Any uncaught exception thrown by the reply callback will be caught and logged.
- Parameters:
message
- the message, possibly null.callback
- aBasicMessageChannel.Reply
callback, possibly null.
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setMessageHandler
@UiThread public void setMessageHandler(@Nullable BasicMessageChannel.MessageHandler<T> handler)
Registers a message handler on this channel for receiving messages sent from the Flutter application.Overrides any existing handler registration for (the name of) this channel.
If no handler has been registered, any incoming message on this channel will be handled silently by sending a null reply.
- Parameters:
handler
- aBasicMessageChannel.MessageHandler
, or null to deregister.
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resizeChannelBuffer
public void resizeChannelBuffer(int newSize)
Adjusts the number of messages that will get buffered when sending messages to channels that aren't fully set up yet. For example, the engine isn't running yet or the channel's message handler isn't set up on the Dart side yet.
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