java.lang.Object | |
↳ | com.google.android.gms.gcm.GoogleCloudMessaging |
The class you use to write a GCM-enabled client application that runs on an Android device. Client applications can receive GCM messages and optionally send messages of their own back to the server.
This class requires Google Play services version 3.1 or higher. For a detailed discussion of how to write a GCM client app, see Implementing GCM Client.
To send or receive messages, your application first needs to get a registration ID. The registration ID identifies the device and application, and also determines which 3rd-party application servers are allowed to send messages to this application instance.
To get a registration ID, you must supply one or more sender IDs. A sender ID is a project
number you acquire from the API console, as described in
Getting Started. The sender ID is
used in the registration process to identify a 3rd-party application server that is permitted to
send messages to the device. The following snippet shows you how to call the
register()
method. For a more comprehensive example, see
Implementing GCM Client.
String SENDER_ID = "My-Sender-ID"; GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(context); String registrationId = gcm.register(SENDER_ID); // Upload the registration ID to your own server // The request to your server should be authenticated if your app is using accounts.
In order to receive GCM messages, you need to declare a permission and a
BroadcastReceiver
in your manifest. This is a backward-compatible subset of what was
required in previous versions of GCM.
To allow the application to use GCM, add this permission to the manifest:
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
GCM delivers messages as a broadcast. The receivers must be registered in the manifest in order to wake up the application.
The com.google.android.c2dm.permission.SEND permission
is held by Google Play
services. This prevents other code from invoking the broadcast receiver. Here is an excerpt
from a sample manifest:
<receiver android:name=".MyReceiver" android:exported="true" android:permission="com.google.android.c2dm.permission.SEND" > <intent-filter> <action android:name="com.google.android.c2dm.intent.RECEIVE" /> <category android:name="YOUR_PACKAGE_NAME" /> </intent-filter> </receiver>
When a GCM connection server delivers the message to your client app, the
BroadcastReceiver
receives the message as an intent. You can either process the
intent in the BroadcastReceiver
, or you can pass off the work of processing the
intent to a service (typically, an IntentService
). If you use a service, your
broadcast receiver should be an instance of WakefulBroadcastReceiver
, to hold a
wake lock while the service is doing its work.
When processing the intent GCM passes into your app's broadcast receiver, you can determine
the message type by calling getMessageType(intent)
. For example:
GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this); String messageType = gcm.getMessageType(intent); ... // Filter messages based on message type. It is likely that GCM will be extended in the future // with new message types, so just ignore message types you're not interested in, or that you // don't recognize. if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR.equals(messageType)) { // It's an error. } else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED.equals(messageType)) { // Deleted messages on the server. } else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) { // It's a regular GCM message, do some work. }
If you are using the XMPP-based Cloud Connection Server, your client app can send upstream messages back to the server. For example:
gcm.send(SENDER_ID + "@gcm.googleapis.com", id, data);For a more details, see Implementing GCM Client.
Constants | |||||||||||
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String | ERROR_MAIN_THREAD | The GCM register() and unregister() methods are
blocking. |
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String | ERROR_SERVICE_NOT_AVAILABLE | The device can't read the response, or there was a 500/503 from the server that can be retried later. | |||||||||
String | MESSAGE_TYPE_DELETED | Returned by getMessageType(Intent) to indicate that the server deleted
some pending messages because they were collapsible. |
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String | MESSAGE_TYPE_MESSAGE | Returned by getMessageType(Intent) to indicate a regular message. |
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String | MESSAGE_TYPE_SEND_ERROR | Returned by getMessageType(Intent) to indicate a send error. |
Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Must be called when your application is done using GCM, to release
internal resources.
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Return the singleton instance of GCM.
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Return the message type from an intent passed into a client app's broadcast receiver.
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Register the application for GCM and return the registration ID.
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Send an upstream ("device to cloud") message.
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Send an upstream ("device to cloud") message.
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Unregister the application.
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Inherited Methods | |||||||||||||||||||||||||||||||||
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From class
java.lang.Object
|
The GCM register()
and unregister()
methods are
blocking. You should not run them in the main thread or in broadcast receivers.
The device can't read the response, or there was a 500/503 from the server that can be retried later. The application should use exponential back off and retry.
Returned by getMessageType(Intent)
to indicate that the server deleted
some pending messages because they were collapsible.
Returned by getMessageType(Intent)
to indicate a regular message.
Returned by getMessageType(Intent)
to indicate a send error.
The intent includes the message ID of the message and an error code.
Must be called when your application is done using GCM, to release internal resources.
Return the singleton instance of GCM.
Return the message type from an intent passed into a client app's broadcast receiver. There are two general categories of messages passed from the server: regular GCM messages, and special GCM status messages. The possible types are:
MESSAGE_TYPE_MESSAGE
—regular message from your server.
MESSAGE_TYPE_DELETED
—special status message indicating that some
messages have been collapsed by GCM.
MESSAGE_TYPE_SEND_ERROR
—special status message indicating that
there were errors sending one of the messages.
Register the application for GCM and return the registration ID. You must call this once, when your application is installed, and send the returned registration ID to the server.
Repeated calls to this method will return the original registration ID.
If you want to modify the list of senders, you must call unregister()
first.
Most applications use a single sender ID. You may use multiple senders if different servers may send messages to the app or for testing.
senderIds | list of project numbers or Google accounts identifying who is allowed to send messages to this application. |
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IOException |
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Send an upstream ("device to cloud") message. You can only use the upstream feature if your GCM implementation uses the XMPP-based Cloud Connection Server. The current limits for max storage time and number of outstanding messages per application are documented in the GCM Developers Guide.
to | string identifying the receiver of the message. For GCM projects IDs
the value is SENDER_ID@gcm.googleapis.com . The SENDER_ID
should be one of the sender IDs used in register() . |
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msgId | ID of the message. This is generated by the application. It must be unique for each message. This allows error callbacks and debugging. |
timeToLive | If 0, we'll attempt to send immediately and return an error if we're not connected. Otherwise, the message will be queued. As for server-side messages, we don't return an error if the message has been dropped because of TTL—this can happen on the server side, and it would require extra communication. |
data | key/value pairs to be sent. Values must be String, any other type will be ignored. |
IllegalArgumentException | |
---|---|
IOException |
Send an upstream ("device to cloud") message. You can only use the upstream feature if your GCM implementation uses the XMPP-based Cloud Connection Server. The message will be queued if we don't have an active connection for the max interval.
to | string identifying the receiver of the message. For GCM project IDs
the value is SENDER_ID@gcm.googleapis.com . The SENDER_ID
should be one of the sender IDs used in register() . |
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msgId | ID of the message. This is generated by the application. It must be unique for each message. This allows error callbacks and debugging. |
data | key/value pairs to be sent. Values must be String—any other type will be ignored. |
IllegalArgumentException | |
IOException |
Unregister the application. Calling unregister()
stops any
messages from the server. This is a blocking call—you shouldn't call
it from the UI thread.
You should rarely (if ever) need to call this method. Not only is it
expensive in terms of resources, but it invalidates your registration ID,
which you should never change unnecessarily. A better approach is to simply
have your server stop sending messages. Only use unregister if you want
to change your sender ID.
IOException | if we can't connect to server to unregister. |
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