java - 如何在 Android 中读取 Firebase 用户数据

Question

如何获取值

-M7U58NYUAHIGAQSlWQx

所以，当我运行最后一个 Activity 时，它得到 -M7U58NYUAHIGAQSlWQx但在它下面，却没有!

它就在“数据”字段下方，我可以读取并显示生日、电子邮件、姓名和电话!

例如values

我做错了什么？

{
  "users" : {
    "f1UXj3DTFFVaCNFK73roMMjMa5F3" : {
      "bDay" : "99/99/9999",
      "data" : {
        "2020" : {
          "5" : {
           "-M7U58NYUAHIGAQSlWQx" : {
              "nome" : "2",
              "valor" : "2"
            }
          }
        }
      },
      "email" : "99@gmail.com",
      "name" : "Bruno",
      "phone" : "999999999"
    }
  }
}

我一整天都在努力寻找，但没有人对我有同样的怀疑......

因此，这是造成这种情况的 3 个类:

AutoUpdate.java 是创建以下“数据”的基础。

package com.example.gestor_contas.TESTE;

import com.example.gestor_contas.DataCenter.Usuario;

import java.util.Calendar;


public class AutoUpdate extends Usuario {


    private String ano;
    private String mes;
    private String nome;
    private String valor;

    public AutoUpdate(){

    }
    public String getNome() {
        return nome;
    }

    public void setNome(String nome) {
        this.nome = nome;
    }

    public String getValor() {
        return valor;
    }

    public AutoUpdate(String ano) {
        this.ano = ano;
    }

    public void setValor(String valor) {
        this.valor = valor;
    }

    public AutoUpdate(String nome, String valor) {
        this.nome = nome;
        this.valor = valor;
    }

    protected String updateAno(){
        return String.valueOf(Calendar.getInstance().get(Calendar.YEAR));
    }
    protected String updateMes(){
        int aux = Calendar.getInstance().get(Calendar.MONTH) + 1;
        return String.valueOf(aux);
    }

}

此 Activity 负责添加具有新值的新“ HashMap ”。

package com.example.gestor_contas.TESTE;
    
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.example.gestor_contas.Base.BaseActivity;
import com.example.gestor_contas.R;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import java.util.HashMap;
import java.util.Map;

public class TesteAdicionar extends BaseActivity{

    private EditText mNome;
    private EditText mValor;
    private Button mEnviar;
    private String ano;
    private String mes;
    private FirebaseDatabase database = FirebaseDatabase.getInstance();
    private DatabaseReference mDatabase ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_teste_auto_update);

        mNome = findViewById(R.id.fieldNome);
        mValor = findViewById(R.id.fieldValor);
        mEnviar = findViewById(R.id.buttonEnviar);
        AutoUpdate up = new AutoUpdate();

        ano = up.updateAno();
        mes = up.updateMes();
        mDatabase = database.getReference("users/" + getUid() + "/data/" + ano+ "/" + mes+"/");
        mEnviar.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                submitPost();
            }
        });
    }
    private void submitPost() {
        final String nomeNF = mNome.getText().toString();
        final String valorNF = mValor.getText().toString();
        Toast.makeText(this, "Posting...", Toast.LENGTH_SHORT).show();
        writeNewPost(nomeNF,valorNF);
    }

    private void writeNewPost(String name, String value) {
        AutoUpdate up = new AutoUpdate(name,value);
        String key = mDatabase.push().getKey();
        Map<String, Object> childUpdates = new HashMap<>();
        childUpdates.put(key, up);
        mDatabase.updateChildren(childUpdates);
        Toast.makeText(this, "Posted!", Toast.LENGTH_SHORT).show();
    }
}

最后一个只负责可视化并从数据库获取

package com.example.gestor_contas.TESTE;

import android.os.Bundle;
import android.widget.Toast;

import androidx.annotation.NonNull;

import com.example.gestor_contas.Base.BaseActivity;
import com.example.gestor_contas.R;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;


public class TesteVisualizar extends BaseActivity {

    private FirebaseDatabase database = FirebaseDatabase.getInstance();
    private DatabaseReference mDatabase;
    private String ano;
    private String mes;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_visualizar);

        AutoUpdate up = new AutoUpdate();
        ano = up.updateAno();
        mes = up.updateMes();

        mDatabase = database.getReference("users" + "/" + getUid() + "/" + "data" + "/" + ano + "/" + mes + "/");

        mDatabase.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                showData(dataSnapshot);
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(TesteVisualizar.this, "3", Toast.LENGTH_SHORT).show();
            }
        });

    }

    private void showData(DataSnapshot dataSnapshot) {


        
    for(DataSnapshot ds : dataSnapshot.getChildren()){
        Toast.makeText(TesteVisualizar.this,  "Inicio", Toast.LENGTH_SHORT).show();
        Toast.makeText(TesteVisualizar.this, ds.getKey(), Toast.LENGTH_SHORT).show();

            AutoUpdate up = new AutoUpdate();
            up.setNome(dataSnapshot.getValue(AutoUpdate.class).getNome());
            Toast.makeText(TesteVisualizar.this,  up.getNome(), Toast.LENGTH_SHORT).show();
       

        Toast.makeText(TesteVisualizar.this,  "Fim", Toast.LENGTH_SHORT).show();
    }

    }
}

Answer 1

使用

up.setNome(ds.getValue(AutoUpdate.class).getNome());

而不是

up.setNome(dataSnapshot.getValue(AutoUpdate.class).getNome());

dataSanpshot:

"5" : {
   "-M7U58NYUAHIGAQSlWQx" : {
          "nome" : "2",
          "valor" : "2"
        }
       }

ds:

"-M7U58NYUAHIGAQSlWQx" : {
          "nome" : "2",
          "valor" : "2"
        }

因此您无法将 dataSnapshot 转换为 AutoUpdate.class。如果需要，可以转换为HashMap:

Map<String, Object> td = (HashMap<String, Object>) dataSnapshot.getValue();