我正在尝试使用教程在我的应用中集成FireBase Cloud Messaging：
https://www.simplifiedcoding.net/firebase-cloud-messaging-tutorial-android/
当我尝试启动应用程序时，我遇到了Null Pointer异常：
这是logcat：
java.lang.NullPointerException: Attempt to invoke virtual method
'boolean com.google.android.gms.common.ConnectionResult.isSuccess()' on a null object reference
at com.google.android.gms.common.internal.zzd$zzi.zzh(Unknown Source)
at com.google.android.gms.common.internal.zzd$zzk.zztp(Unknown Source)
at com.google.android.gms.common.internal.zzd$zza.zzc(Unknown Source)
at com.google.android.gms.common.internal.zzd$zza.zzw(Unknown Source)
at com.google.android.gms.common.internal.zzd$zze.zztr(Unknown Source)
at com.google.android.gms.common.internal.zzd$zzd.handleMessage(Unknown Source)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5942)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1400)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1195)
这是我的build.gradle：
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.0.0'
//FireBase dependency
classpath 'com.google.gms:google-services:3.0.0'
}
}
apply plugin: 'android'
dependencies {
compile fileTree(include: '*.jar', dir: 'libs')
//FireBase dependency
compile 'com.google.firebase:firebase-messaging:10.0.1'
}
android {
compileSdkVersion 20
buildToolsVersion '23.0.3'
sourceSets {
main {
manifest.srcFile 'AndroidManifest.xml'
java.srcDirs = ['src']
resources.srcDirs = ['src']
aidl.srcDirs = ['src']
renderscript.srcDirs = ['src']
res.srcDirs = ['res']
assets.srcDirs = ['assets']
jniLibs.srcDirs = ['libs']
}
instrumentTest.setRoot('tests')
// Move the build types to build-types/<type>
// For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ...
// This moves them out of them default location under src/<type>/... which would
// conflict with src/ being used by the main source set.
// Adding new build types or product flavors should be accompanied
// by a similar customization.
debug.setRoot('build-types/debug')
release.setRoot('build-types/release')
}
lintOptions {
abortOnError false
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_7
targetCompatibility JavaVersion.VERSION_1_7
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_7
targetCompatibility JavaVersion.VERSION_1_7
}
productFlavors {
x86 {
ndk {
abiFilter "x86"
}
}
arm {
ndk {
abiFilters "armeabi-v7a", "armeabi"
}
minSdkVersion 17
}
}
packagingOptions {
exclude 'META-INF/DEPENDENCIES'
exclude 'META-INF/NOTICE'
exclude 'META-INF/LICENSE'
exclude 'META-INF/license.txt'
exclude 'META-INF/notice.txt'
}
defaultConfig {
minSdkVersion 17
applicationId "com.nytshft.evyt"
}
}
//FireBase
apply plugin: 'com.google.gms.google-services'
注意：我的应用程序中没有应用程序模块。我有一个build.gradle文件。
是否与build.gradle有关？在官方网站上，他们说要在app文件夹中复制json文件。不幸的是，我的应用程序没有一个这样的文件夹。这是ProjectView Screenshot 。他们还说要在app的build.gradle中添加一些依赖项。由于我没有任何app文件夹，我在项目的build.gradle文件中进行了这些更改。
MyFirebaseInstanceIDService.java：
class MyFirebaseInstanceIDService extends FirebaseInstanceIdService {
private static final String TAG = "MyFirebaseIIDService";
@Override
public void onTokenRefresh() {
// Get updated InstanceID token.
String refreshedToken = FirebaseInstanceId.getInstance().getToken();
Log.d(TAG, "Refreshed token: " + refreshedToken);
sendRegistrationToServer(refreshedToken);
}
private void sendRegistrationToServer(String token) {
// TODO: Implement this method to send token to your app server.
}
MyFireBaseMessagingService.java
class MyFirebaseMessagingService extends FirebaseMessagingService {
private static final String TAG = "MyFirebaseMsgService";
@Override
public void onMessageReceived(RemoteMessage remoteMessage) {
Log.d(TAG, "From: " + remoteMessage.getFrom());
// Check if message contains a data payload.
if (remoteMessage.getData().size() > 0) {
Log.d(TAG, "Message data payload: " + remoteMessage.getData());
}
// Check if message contains a notification payload.
if (remoteMessage.getNotification() != null) {
Log.d(TAG, "Message Notification Body: " + remoteMessage.getNotification().getBody());
//Calling method to generate notification
//sendNotification(remoteMessage.getNotification().getBody());
}
Toast.makeText(getApplicationContext(), "Push notification: " + remoteMessage.getNotification().getBody(), Toast.LENGTH_LONG).show();
}
/**
* Create and show a simple notification containing the received FCM message.
* This method is only generating push notification.
* @param messageBody FCM message body received.
*/
private void sendNotification(String messageBody) {
Intent intent = new Intent(this, MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
PendingIntent.FLAG_ONE_SHOT);
Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
.setSmallIcon(R.drawable.androidwidget_logo)
.setContentTitle("FCM Message")
.setContentText(messageBody)
.setAutoCancel(true)
.setSound(defaultSoundUri)
.setContentIntent(pendingIntent);
NotificationManager notificationManager =
(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
notificationManager.notify(0 /* ID of notification */, notificationBuilder.build());
}
答案 0 :(得分：1)
经过几天的调查，我终于找到了导致Null指针异常的原因。有一个google-play-services.jar驻留在项目的libs文件夹中。（为其他模块添加而不是FireBase）与我们添加的apply plugin: 'com.google.gms.google-services'冲突对于FireBase。
我不得不从libs中移除罐子并添加相同的依赖性，如下所示：
compile 'com.google.android.gms:play-services:10.0.1'
答案 1 :(得分：0)
很多人都忘记了这种依赖compile 'com.google.firebase:firebase-core:9.6.1'。 firebase的所有依赖项都需要它们的核心，您可以在此post中了解有关此内容的更多信息，请记住将firebase-messaging更新为上一版本compile 'com.google.firebase:firebase-messaging:9.6.1'。
如果我帮助了你并且编程很好，请告诉我！