java - Android App 无法将数据写入 Firebase 数据库

问题描述

我正在尝试按照 Udacity 的教程使用 Firebase 构建聊天应用程序。尽管我遵循了所有说明，但在按下按钮时将数据写入 firebase 实时数据库时遇到了麻烦。

应用程序在模拟器上完美运行。但是每当我点击发送按钮时，数据库中都不会显示任何数据。检查应用程序的屏幕截图。

添加了谷歌服务 json 文件。在Build.gradle (app)文件
中添加了所有需要和应用 google services 插件的依赖项。在Build.grade（项目）文件中添加了 google services 类路径。将 firebase 安全规则更改为测试模式。

我究竟做错了什么？请帮忙。

MainActivity.java 文件如下所示：

package com.google.firebase.udacity.friendlychat;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.Editable;
import android.text.InputFilter;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;
import android.widget.ProgressBar;

import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.DatabaseReference;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";

    public static final String ANONYMOUS = "anonymous";
    public static final int DEFAULT_MSG_LENGTH_LIMIT = 1000;

    private ListView mMessageListView;
    private MessageAdapter mMessageAdapter;
    private ProgressBar mProgressBar;
    private ImageButton mPhotoPickerButton;
    private EditText mMessageEditText;
    private Button mSendButton;

    private String mUsername;

    private FirebaseDatabase mFirebaseDatabase;
    private DatabaseReference mMessagesDatabaseReference;

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

        mUsername = ANONYMOUS;

        mFirebaseDatabase = FirebaseDatabase.getInstance();
        mMessagesDatabaseReference = mFirebaseDatabase.getReference().child("messages");

        // Initialize references to views
        mProgressBar = (ProgressBar) findViewById(R.id.progressBar);
        mMessageListView = (ListView) findViewById(R.id.messageListView);
        mPhotoPickerButton = (ImageButton) findViewById(R.id.photoPickerButton);
        mMessageEditText = (EditText) findViewById(R.id.messageEditText);
        mSendButton = (Button) findViewById(R.id.sendButton);

        // Initialize message ListView and its adapter
        List<FriendlyMessage> friendlyMessages = new ArrayList<>();
        mMessageAdapter = new MessageAdapter(this, R.layout.item_message, friendlyMessages);
        mMessageListView.setAdapter(mMessageAdapter);

        // Initialize progress bar
        mProgressBar.setVisibility(ProgressBar.INVISIBLE);

        // ImagePickerButton shows an image picker to upload a image for a message
        mPhotoPickerButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                // TODO: Fire an intent to show an image picker
            }
        });

        // Enable Send button when there's text to send
        mMessageEditText.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
                if (charSequence.toString().trim().length() > 0) {
                    mSendButton.setEnabled(true);
                } else {
                    mSendButton.setEnabled(false);
                }
            }

            @Override
            public void afterTextChanged(Editable editable) {
            }
        });
        mMessageEditText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(DEFAULT_MSG_LENGTH_LIMIT)});

        // Send button sends a message and clears the EditText
        mSendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                FriendlyMessage friendlyMessage = new FriendlyMessage(mMessageEditText.getText().toString(), mUsername, null);
                // Clear input box
                mMessageEditText.setText("");
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        return super.onOptionsItemSelected(item);
    }
}

标签： javaandroidfirebasefirebase-realtime-database

java - Android App 无法将数据写入 Firebase 数据库

问题描述

解决方案

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