我正在尝试按照Udacity的教程与Firebase构建聊天应用程序 . 虽然我按照每条指令操作,但是按下按钮时我很难将数据写入firebase实时数据库 .
应用程序在模拟器上运行完美 . 但每当我点击发送按钮时,数据库中都不会显示任何数据 . 检查应用的屏幕截图 .
添加了google服务json文件 .
在 Build.gradle (app) 文件中添加了所需的所有依赖项并应用了google services插件 .
在 Build.grade (project) 文件中添加了google服务类路径 .
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 file 看起来像这样:
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);
}
}
2 回答
没有任何东西进入你的数据库,因为你根本就没有在里面写东西 . 您正在创建
FriendlyMessage
类的对象,但您没有使用它做任何事情 . 要解决此问题,请使用以下代码行将该对象写入Firebase数据库:您应该在声明
friendlyMessage
对象之后立即放置这行代码 .之后,您必须从firebase读取数据并将其添加到列表中 .