WebMessagePort
public abstract class WebMessagePort
extends Object
| java.lang.Object | |
| ↳ | android.webkit.WebMessagePort |
The Java representation of the HTML5 message ports.
A Message port represents one endpoint of a Message Channel. In Android webview, there is no separate Message Channel object. When a message channel is created, both ports are tangled to each other and started, and then returned in a MessagePort array, see WebView.createWebMessageChannel for creating a message channel.
When a message port is first created or received via transfer, it does not have a WebMessageCallback to receive web messages. The messages are queued until a WebMessageCallback is set.
A message port should be closed when it is not used by the embedder application anymore. A closed port cannot be transferred or cannot be reopened to send messages. Close can be called multiple times.
When a port is transferred to JS, it cannot be used to send or receive messages at the Java side anymore. Different from HTML5 Spec, a port cannot be transferred if one of these has ever happened: i. a message callback was set, ii. a message was posted on it. A transferred port cannot be closed by the application, since the ownership is also transferred.
It is possible to transfer both ports of a channel to JS, for example for communication between subframes.
Summary
Nested classes | |
|---|---|
class | WebMessagePort.WebMessageCallback The listener for handling MessagePort events. |
Public methods | |
|---|---|
abstract void | close() Close the message port and free any resources associated with it. |
abstract void | postMessage(WebMessage message) Post a WebMessage to the entangled port. |
abstract void | setWebMessageCallback(WebMessagePort.WebMessageCallback callback, Handler handler) Sets a callback to receive message events on the handler that is provided by the application. |
abstract void | setWebMessageCallback(WebMessagePort.WebMessageCallback callback) Sets a callback to receive message events on the main thread. |
Inherited methods | |
|---|---|
Public methods
close
public abstract void close ()
Close the message port and free any resources associated with it.
postMessage
public abstract void postMessage (WebMessage message)
Post a WebMessage to the entangled port.
| Parameters | |
|---|---|
message | WebMessage: the message from Java to JS. |
| Throws | |
|---|---|
IllegalStateException | If message port is already transferred or closed. |
setWebMessageCallback
public abstract void setWebMessageCallback (WebMessagePort.WebMessageCallback callback, Handler handler)
Sets a callback to receive message events on the handler that is provided by the application.
| Parameters | |
|---|---|
callback | WebMessagePort.WebMessageCallback: the message callback. |
handler | Handler: the handler to receive the message messages. |
setWebMessageCallback
public abstract void setWebMessageCallback (WebMessagePort.WebMessageCallback callback)
Sets a callback to receive message events on the main thread.
| Parameters | |
|---|---|
callback | WebMessagePort.WebMessageCallback: the message callback. |
Content and code samples on this page are subject to the licenses described in the Content License. Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
Last updated 2025-02-10 UTC.