问题
I have been searching for some days now how to implement Google Cloud Messaging for Android, but I'm with some serious doubts about it.
I mean, apparently Google put some good informations online, like here and here, but I'm confused about all the logic. One page talks about the client side, and another about the server side. Great, but how do I bind all of it together? How do I implement HTTP and/or XMPP protocol to communicate with the GCM connection server(s)?
I would like implement a basic HelloWorld for GCM, that would work with the following steps:
1. App send a message (say "HelloWorld") to GCM;
2. Receive that message from GCM and add it to a TextView.
What are the steps needed to achieve this basic app?
Thank you,
回答1:
If you have read the two links in your question and understood GCM key concepts, then you can refer to the following sample codes:
Of course, let's assume that you have finished:
- Create a project and its server API key at Google Developers Console
- Set permissions in your AndroidManifest files like this
<uses-permission android:name="android.permission.INTERNET" />
Server side:
public class MainActivity extends AppCompatActivity {
private TextView mTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mTextView = (TextView) findViewById(R.id.textView);
new GCMRequest().execute();
}
...
private class GCMRequest extends AsyncTask<Void, Void, String> {
@Override
protected String doInBackground(Void... voids) {
final String API_KEY = "..."; // An API key saved on the app server that gives the app server authorized access to Google services
final String CLIENT_REG_ID = "..."; //An ID issued by the GCM connection servers to the client app that allows it to receive messages
final String postData = "{ \"registration_ids\": [ \"" + CLIENT_REG_ID + "\" ], " +
"\"delay_while_idle\": true, " +
"\"data\": {\"tickerText\":\"My Ticket\", " +
"\"contentTitle\":\"My Title\", " +
"\"message\": \"Test GCM message from GCMServer-Android\"}}";
try {
URL url = new URL("https://android.googleapis.com/gcm/send");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setDoInput(true);
urlConnection.setDoOutput(true);
urlConnection.setRequestMethod("POST");
urlConnection.setRequestProperty("Content-Type", "application/json");
urlConnection.setRequestProperty("Authorization", "key=" + API_KEY);
OutputStream outputStream = new BufferedOutputStream(urlConnection.getOutputStream());
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStream, "utf-8"));
writer.write(postData);
writer.flush();
writer.close();
outputStream.close();
int responseCode = urlConnection.getResponseCode();
InputStream inputStream;
if (responseCode < HttpURLConnection.HTTP_BAD_REQUEST) {
inputStream = urlConnection.getInputStream();
} else {
inputStream = urlConnection.getErrorStream();
}
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String temp, response = "";
while ((temp = bufferedReader.readLine()) != null) {
response += temp;
}
return response;
} catch (IOException e) {
e.printStackTrace();
return e.toString();
}
}
@Override
protected void onPostExecute(String message) {
super.onPostExecute(message);
if (mTextView != null) {
try {
JSONObject jsonObject = new JSONObject(message);
mTextView.setText(jsonObject.toString(5));
} catch (JSONException e) {
e.printStackTrace();
mTextView.setText(e.toString());
}
}
}
}
}
Client-side:
MainActivity.java:
public class MainActivity extends AppCompatActivity {
private final Context mContext = this;
private final String SENDER_ID = "..."; // Project Number at https://console.developers.google.com/project/...
private final String SHARD_PREF = "com.example.gcmclient_preferences";
private final String GCM_TOKEN = "gcmtoken";
public static TextView mTextView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SharedPreferences appPrefs = mContext.getSharedPreferences(SHARD_PREF, Context.MODE_PRIVATE);
String token = appPrefs.getString(GCM_TOKEN, "");
if (token.isEmpty()) {
try {
getGCMToken();
} catch (Exception e) {
e.printStackTrace();
}
}
mTextView = (TextView) findViewById(R.id.textView);
}
...
private void getGCMToken() {
new AsyncTask<Void, Void, Void>() {
@Override
protected Void doInBackground(Void... params) {
try {
InstanceID instanceID = InstanceID.getInstance(mContext);
String token = instanceID.getToken(SENDER_ID, GoogleCloudMessaging.INSTANCE_ID_SCOPE, null);
if (token != null && !token.isEmpty()) {
SharedPreferences appPrefs = mContext.getSharedPreferences(SHARD_PREF, Context.MODE_PRIVATE);
SharedPreferences.Editor prefsEditor = appPrefs.edit();
prefsEditor.putString(GCM_TOKEN, token);
prefsEditor.apply();
}
Log.i("GCM", token);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}.execute();
}
}
GcmService.java:
public class GcmService extends GcmListenerService {
@Override
public void onMessageReceived(String from, Bundle data) {
JSONObject jsonObject = new JSONObject();
Set<String> keys = data.keySet();
for (String key : keys) {
try {
jsonObject.put(key, data.get(key));
} catch (JSONException e) {
e.printStackTrace();
}
}
try {
sendNotification("Received: " + jsonObject.toString(5));
} catch (JSONException e) {
e.printStackTrace();
}
}
@Override
public void onDeletedMessages() {
sendNotification("Deleted messages on server");
}
@Override
public void onMessageSent(String msgId) {
sendNotification("Upstream message sent. Id=" + msgId);
}
@Override
public void onSendError(String msgId, String error) {
sendNotification("Upstream message send error. Id=" + msgId + ", error" + error);
}
private void sendNotification(final String msg) {
Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {
@Override
public void run() {
if (MainActivity.mTextView != null) {
MainActivity.mTextView.setText(msg);
}
}
});
}
}
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.gcmandroid" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<permission android:name="com.example.gcm.permission.C2D_MESSAGE"
android:protectionLevel="signature" />
<uses-permission android:name="com.example.gcm.permission.C2D_MESSAGE" />
<application
android:allowBackup="true"
android:fullBackupContent="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<receiver
android:name="com.google.android.gms.gcm.GcmReceiver"
android:exported="true"
android:permission="com.google.android.c2dm.permission.SEND" >
<intent-filter>
<action android:name="com.google.android.c2dm.intent.REGISTRATION" />
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
<category android:name="com.example.gcm" />
</intent-filter>
</receiver>
<service android:name=".GcmService" android:exported="false">
<intent-filter>
<action android:name="com.google.android.c2dm.intent.RECEIVE" />
</intent-filter>
</service>
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
来源：https://stackoverflow.com/questions/32299997/how-to-implement-a-gcm-hello-world-for-android-using-android-studio