最佳答案
确保在 Android 中首先调用 FirebaseApp.initializeApp (Context)
我正面临这个问题，看到了一些答案，但没有得到任何适当的解决方案。
我已经使用以前的版本的 Firebase工作得很好，但是当我试图升级使用 升级和更新 Firebase类到 DatabaseReference它显示错误和不工作。
我添加我的清单文件完整的代码，所以请帮助我解决这个问题。
这是我的 manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="firebasechat.com.firebasechat">
<uses-permission android:name="android.permission.INTERNET" />
<application
android:allowBackup="true"
android:name=".Activity.SimpleBlog"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".Activity.RegisterActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
我的 Module app如下。
apply plugin: 'com.android.application'
android {
compileSdkVersion 26
buildToolsVersion "26.0.0"
defaultConfig {
applicationId "firebasechat.com.firebasechat"
minSdkVersion 15
targetSdkVersion 26
versionCode 1
versionName "1.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
multiDexEnabled true
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
packagingOptions {
exclude 'META-INF/LICENSE'
exclude 'META-INF/LICENSE-FIREBASE.txt'
exclude 'META-INF/NOTICE'
}
}
dependencies {
compile fileTree(include: ['*.jar'], dir: 'libs')
androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
exclude group: 'com.android.support', module: 'support-annotations'
})
compile 'com.android.support:appcompat-v7:26.+'
compile 'com.android.volley:volley:1.0.0'
compile "com.google.firebase:firebase-database:11.0.0"
compile 'com.google.android.gms:play-services:11.0.0'
compile 'com.android.support:recyclerview-v7:25.0.0'
testCompile 'junit:junit:4.12'
testCompile 'junit:junit:4.12'
}
和 Project gradle
// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.3.3'
classpath 'com.google.gms:google-services:4.2.0'// Updated version of google service
}
}
allprojects {
repositories {
jcenter()
maven {
url "https://maven.google.com" // Google's Maven repository
}
}
}
task clean(type: Delete) {
delete rootProject.buildDir
}
下面是我的 Activity。
public class RegisterActivity extends AppCompatActivity {
EditText username, password;
Button registerButton;
String user, pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
username = (EditText)findViewById(R.id.username);
password = (EditText)findViewById(R.id.password);
registerButton = (Button)findViewById(R.id.registerButton);
FirebaseApp.initializeApp(this);
registerButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
user = username.getText().toString();
pass = password.getText().toString();
final ProgressDialog pd = new ProgressDialog(RegisterActivity.this);
pd.setMessage("Loading...");
pd.show();
String url = "https://pure-coda-174710.firebaseio.com/users.json";
StringRequest request = new StringRequest(Request.Method.GET, url, new Response.Listener<String>(){
@Override
public void onResponse(String s) {
// Firebase reference = new Firebase("https://pure-coda-174710.firebaseio.com/users");
DatabaseReference reference = FirebaseDatabase.getInstance()
.getReferenceFromUrl("https://pure-coda-174710.firebaseio.com/users");
if(s.equals("null")) {
reference.child(user).child("password").setValue(pass);
Toast.makeText(RegisterActivity.this, "registration successful", Toast.LENGTH_LONG).show();
}
else {
try {
JSONObject obj = new JSONObject(s);
if (!obj.has(user)) {
reference.child(user).child("password").setValue(pass);
Toast.makeText(RegisterActivity.this, "registration successful", Toast.LENGTH_LONG).show();
} else {
Toast.makeText(RegisterActivity.this, "username already exists", Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
pd.dismiss();
}
},new Response.ErrorListener(){
@Override
public void onErrorResponse(VolleyError volleyError) {
System.out.println("" + volleyError );
pd.dismiss();
}
});
RequestQueue rQueue = Volley.newRequestQueue(RegisterActivity.this);
rQueue.add(request);
}
});
}
}
