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我正在开发使用Firebase技术的基本Android聊天应用程序。关于将图片上传到Firebase数据库有一个问题。我点击ImageButton从我的画廊中选择一个图像。当我选择图片时，我的图片无法上传到Firebase数据库。相反，我的应用程序崩溃，将图片上传到Firebase时发生NullPointerException
private static final int RC_PHOTO_PICKER = 1;
ImageButton imageBtn;
private FirebaseStorage storage;
private DatabaseReference databaseRef;
private StorageReference storageRef;
private FirebaseApp app;
private FirebaseDatabase database;
@Override
protected void onCreate(Bundle savedInstanceState)
{
// image upload code
app = FirebaseApp.getInstance();
database = FirebaseDatabase.getInstance(app);
storage = FirebaseStorage.getInstance(app);
storageRef=storage.getReferenceFromUrl("gs://friendlychat-8a091.appspot.com/");
storageRef=storage.getReference("images");
imageBtn = (ImageButton)findViewById(R.id.imageBtn);
imageBtn.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("image/jpeg");
intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
startActivityForResult(Intent.createChooser(intent, getString(R.string.complete_action_with)), RC_PHOTO_PICKER);
}
});
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
if(requestCode==RC_PHOTO_PICKER && resultCode==RESULT_OK)
{
Uri selectedImageUri = data.getData();
final StorageReference PhotoRef=storageRef.child("images/"+selectedImageUri.getLastPathSegment());
PhotoRef.putFile(selectedImageUri)
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception exception)
{
Toast.makeText(getApplicationContext(),"error ="+exception.getMessage(),Toast.LENGTH_LONG).show();
}
})
.addOnSuccessListener(this, new OnSuccessListener<UploadTask.TaskSnapshot>() {
@Override
public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
Uri downloaduri = taskSnapshot.getDownloadUrl();
mMessageEditText.setText(downloaduri.toString());
}
});
}
}
这是logcat的消息时，我选择的图像形成画廊
07-30 18:50:00.946 5268-5268/com.google.firebase.codelab.friendlychat D/MainActivity: onActivityResult: requestCode=1, resultCode=-1
07-30 18:50:00.962 5268-5268/com.google.firebase.codelab.friendlychat D/AndroidRuntime: Shutting down VM
07-30 18:50:00.962 5268-5268/com.google.firebase.codelab.friendlychat W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x411342a0)
07-30 18:50:01.188 5268-5268/com.google.firebase.codelab.friendlychat D/FirebaseCrashApiImpl: throwable java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://media/external/images/media/757 (has extras) }} to activity {com.google.firebase.codelab.friendlychat/com.google.firebase.codelab.friendlychat.MainActivity}: java.lang.NullPointerException
07-30 18:50:01.290 5268-5268/com.google.firebase.codelab.friendlychat E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=Intent { dat=content://media/external/images/media/757 (has extras) }} to activity {com.google.firebase.codelab.friendlychat/com.google.firebase.codelab.friendlychat.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.deliverResults(ActivityThread.java:3179)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3222)
at android.app.ActivityThread.access$1100(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1276)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4895)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.google.firebase.codelab.friendlychat.MainActivity.onActivityResult(MainActivity.java:329)
at android.app.Activity.dispatchActivityResult(Activity.java:5347)
at android.app.ActivityThread.deliverResults(ActivityThread.java:3175)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:3222)
at android.app.ActivityThread.access$1100(ActivityThread.java:140)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1276)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4895)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
at dalvik.system.NativeStart.main(Native Method)
07-30 18:53:01.196 5268-5270/com.google.firebase.codelab.friendlychat D/dalvikvm: GC_CONCURRENT freed 454K, 10% free 10859K/12039K, paused 19ms+7ms, total 76ms
07-30 18:53:01.259 5268-5276/com.google.firebase.codelab.friendlychat D/AbsListView: [unregisterDoubleTapMotionListener]
07-30 18:53:01.259 5268-5276/com.google.firebase.codelab.friendlychat I/MotionRecognitionManager: .unregisterListener :/listener count = 0->0, [email protected]
如果您的应用程序已经崩溃，然后按[编辑]与logcat的请 –
请端口你的logcat错误信息让我们去调试。对于任何人来说，“不幸的应用程序已停止工作”消息都无法帮助您。 –
您在'MainActivity'的第329行有'NullPointerException'。在那里设置一个断点并查看哪个变量为'null'。请参阅http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it。除此之外：您不会将图片上传到Firebase数据库，而是上传到Firebase存储。这是一件好事（Firebase存储用于存储这些文件），但它是一个完全不同的API。 –