如何从当前登录的用户 Firebase 获取数据

Question

我想在我的应用程序中获取当前登录用户的所有数据，但是当我进入应该显示数据的活动时，应用程序停止工作。我已经按照Firebase网站上的指南正确设置了Firebase，我可以使用身份验证登录，将数据保存到Firebase中，还可以显示所有数据，但现在我只想显示当前登录用户的数据。

这是我应该显示数据的活动

public class RsolverAccount extends AppCompatActivity {
private FirebaseAuth firebaseAuth;
TextView showEmail;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.rsolveraccount);
setWidget();
showData();
}
private void showData () {
DatabaseReference mDatabase;
mDatabase = FirebaseDatabase.getInstance().getReference().child("userdesc : "+ firebaseAuth.getCurrentUser().getUid());
ValueEventListener postListener = new ValueEventListener() {
@Override
public void onDataChange(com.google.firebase.database.DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
showEmail.setText(user.getEmail());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
mDatabase.addValueEventListener(postListener);
}
public void setWidget() {
showEmail = (TextView) findViewById(R.id.showEmail);
}
}

这是我的杰森树

sraboetapp 
+description
-userdesc
-LquV8N1AJbRdhSKMA2T
email: "[e-mail]"
id: "870788464845"
name: "bry5"
pass: "123456"
phone: "484854484546"

这是我的日志猫

2019-10-17 16:20:11.208 11014-11014/? I/ample.rsolveap: Not late-enabling -Xcheck:jni (already on)
2019-10-17 16:20:11.226 11014-11014/? E/ample.rsolveap: Unknown bits set in runtime_flags: 0x8000
2019-10-17 16:20:11.226 11014-11014/? W/ample.rsolveap: Unexpected CPU variant for X86 using defaults: x86
2019-10-17 16:20:11.583 11014-11049/com.example.rsolveapp W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
2019-10-17 16:20:11.596 11014-11014/com.example.rsolveapp D/FirebaseAuth: Notifying id token listeners about user ( 0dkRQhKR1rQBcAUVYcULtI0C4zN2 ).
2019-10-17 16:20:11.598 11014-11014/com.example.rsolveapp D/FirebaseApp: com.google.firebase.iid.FirebaseInstanceId is not linked. Skipping initialization.
2019-10-17 16:20:11.598 11014-11014/com.example.rsolveapp D/FirebaseApp: com.google.firebase.crash.FirebaseCrash is not linked. Skipping initialization.
2019-10-17 16:20:11.599 11014-11014/com.example.rsolveapp D/FirebaseApp: com.google.android.gms.measurement.AppMeasurement is not linked. Skipping initialization.
2019-10-17 16:20:11.599 11014-11014/com.example.rsolveapp I/FirebaseInitProvider: FirebaseApp initialization successful
2019-10-17 16:20:11.593 11014-11014/com.example.rsolveapp W/RenderThread: type=1400 audit(0.0:41): avc: denied { write } for name="property_service" dev="tmpfs" ino=6749 scontext=u:r:untrusted_app_27:s0:c130,c256,c512,c768 tcontext=u:object_r:property_socket:s0 tclass=sock_file permissive=0 app=com.example.rsolveapp
2019-10-17 16:20:11.608 11014-11056/com.example.rsolveapp D/libEGL: Emulator has host GPU support, qemu.gles is set to 1.
2019-10-17 16:20:11.608 11014-11056/com.example.rsolveapp W/libc: Unable to set property "qemu.gles" to "1": connection failed; errno=13 (Permission denied)
2019-10-17 16:20:11.619 11014-11056/com.example.rsolveapp D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
2019-10-17 16:20:11.620 11014-11056/com.example.rsolveapp D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
2019-10-17 16:20:11.622 11014-11056/com.example.rsolveapp D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
2019-10-17 16:20:11.639 11014-11051/com.example.rsolveapp W/DynamiteModule: Local module descriptor class for com.google.firebase.auth not found.
2019-10-17 16:20:11.646 11014-11051/com.example.rsolveapp I/FirebaseAuth: [FirebaseAuth:] Loading module via FirebaseOptions.
2019-10-17 16:20:11.646 11014-11051/com.example.rsolveapp I/FirebaseAuth: [FirebaseAuth:] Preparing to create service connection to gms implementation
2019-10-17 16:20:11.673 11014-11014/com.example.rsolveapp W/ample.rsolveap: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
2019-10-17 16:20:11.673 11014-11014/com.example.rsolveapp W/ample.rsolveap: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
2019-10-17 16:20:11.728 11014-11014/com.example.rsolveapp D/FirebaseApp: Notifying auth state listeners.
2019-10-17 16:20:11.728 11014-11014/com.example.rsolveapp D/FirebaseApp: Notified 0 auth state listeners.
2019-10-17 16:20:11.750 11014-11054/com.example.rsolveapp W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2019-10-17 16:20:11.752 11014-11054/com.example.rsolveapp D/eglCodecCommon: setVertexArrayObject: set vao to 0 (0) 0 0
2019-10-17 16:20:11.752 11014-11054/com.example.rsolveapp D/EGL_emulation: eglCreateContext: 0xe151a180: maj 3 min 1 rcv 4
2019-10-17 16:20:11.769 11014-11054/com.example.rsolveapp D/EGL_emulation: eglMakeCurrent: 0xe151a180: ver 3 1 (tinfo 0xe150f480)
2019-10-17 16:20:11.771 11014-11054/com.example.rsolveapp E/eglCodecCommon: glUtilsParamSize: unknow param 0x000082da
2019-10-17 16:20:11.771 11014-11054/com.example.rsolveapp E/eglCodecCommon: glUtilsParamSize: unknow param 0x000082da
2019-10-17 16:20:11.782 11014-11054/com.example.rsolveapp W/Gralloc3: mapper 3.x is not supported
2019-10-17 16:20:11.785 11014-11054/com.example.rsolveapp D/eglCodecCommon: allocate: Ask for block of size 0x1000
2019-10-17 16:20:11.785 11014-11054/com.example.rsolveapp D/eglCodecCommon: allocate: ioctl allocate returned offset 0x3ff807000 size 0x2000
2019-10-17 16:20:11.794 11014-11054/com.example.rsolveapp D/EGL_emulation: eglMakeCurrent: 0xe151a180: ver 3 1 (tinfo 0xe150f480)
2019-10-17 16:20:11.813 11014-11054/com.example.rsolveapp D/eglCodecCommon: setVertexArrayObject: set vao to 0 (0) 1 0

这是我的用户类

package com.example.rsolveapp;
import com.google.firebase.database.IgnoreExtraProperties;
import java.io.Serializable;
public class User implements Serializable{
private String email;
private String name, pass, id, phone;
private String key;
public User(){
}
public String getKey(){
return key;
}
public void setKey(String key){
this.key=key;
}
public String getEmail(){
return email;
}
public void setEmail(String email){
this.email=email;
}
public String getName(){
return name;
}
public void setName(String name){
this.name=name;
}
public String getPass(){
return pass;
}
public void setPass(String pass){
this.pass=pass;
}
public String getId(){
return id;
}
public void setId(String id){
this.id=id;
}
public String getPhone(){
return phone;
}
public void setPhone(String phone){
this.phone=phone;
}
@Override
public String toString(){
return " "+email+"/n"+
" "+name+"/n"+
" "+pass+"/n"+
" "+id+"/n"+
" "+phone;
}
public User(String Remail, String Rname, String Rpass, String Rid, String Rphone){
email=Remail;
name=Rname;
pass=Rpass;
id=Rid;
phone=Rphone;
}
}

编辑：这是我现在的活动

public class RsolverAccount extends AppCompatActivity {

TextView showEmail;
private static final String TAG = RsolverAccount.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.rsolveraccount);
setWidget();
showData();
}
private void showData () {
FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
if(firebaseUser != null) {
String email = firebaseUser.getEmail();
Log.d(TAG, email);
}
FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
DatabaseReference mDatabase;
mDatabase = FirebaseDatabase.getInstance().getReference().child("sraboetapp").child("userdesc").child(FirebaseAuth.getInstance().getCurrentUser().getUid());
ValueEventListener postListener = new ValueEventListener() {
@Override
public void onDataChange(com.google.firebase.database.DataSnapshot dataSnapshot) {
User user = dataSnapshot.getValue(User.class);
showEmail.setText(user.getEmail());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
};
mDatabase.addValueEventListener(postListener);
}
public void setWidget() {
showEmail = (TextView) findViewById(R.id.showEmail);
}
}

这是我得到的错误

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.rsolveapp, PID: 13698
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.rsolveapp.User.getEmail()' on a null object reference
at com.example.rsolveapp.RsolverAccount$1.onDataChange(RsolverAccount.java:45)
at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@16.0.4:75)
at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@16.0.4:63)
at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@16.0.4:55)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Answer 1

根据您的评论，您会收到以下错误：

尝试调用虚拟方法 'com.google.firebase.auth.FirebaseUser

com.google.firebase.auth.FirebaseAuth.getCurrentUser(('

因为您的firebaseAuth对象是null.您没有初始化它。要解决此问题，只需添加以下代码行：

FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();

作为showData()方法的第一行。

编辑：

FirebaseUser firebaseUser = FirebaseAuth.getInstance().getCurrentUser();
if(firebaseUser != null) {
String email = firebaseUser.getEmail();
Log.d(TAG, email);
}