Java Firebase赢得';t触发数据更改事件
我在Android应用程序中使用Firebase。我正在尝试使用Firebase作为NOSQL数据库,这是我的数据检索对象Java Firebase赢得';t触发数据更改事件,java,android,firebase,firebase-realtime-database,Java,Android,Firebase,Firebase Realtime Database,我在Android应用程序中使用Firebase。我正在尝试使用Firebase作为NOSQL数据库,这是我的数据检索对象 public class FirebaseManager { private static final String DB_REF = "mainframeradio"; private static final String STREAM_REF = "streams"; public static List<MediaStream>
public class FirebaseManager {
private static final String DB_REF = "mainframeradio";
private static final String STREAM_REF = "streams";
public static List<MediaStream> getMediaStreams(Context context) {
final List<MediaStream> mediaStreams = new ArrayList<>();
FirebaseDatabase db = FirebaseDatabase.getInstance();
DatabaseReference dbRef = db.getReference(STREAM_REF);
dbRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
Map<String, Object> streams = (Map<String, Object>) dataSnapshot.getValue();
if (!streams.isEmpty()) {
for (Object stream : streams.values()) {
String protocol = (String) ((Map) stream).get("protocol");
String host = (String) ((Map) stream).get("host");
int port = (int) ((Map) stream).get("port");
String media = (String) ((Map) stream).get("media");
String metadata = (String) ((Map) stream).get("metadata");
String streamName = (String) ((Map) stream).get("streamName");
MediaStream mediaStream = new MediaStream(protocol, host, port, media, metadata, streamName);
mediaStreams.add(mediaStream);
}
} else {
L.d("No media streams found on the server.");
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
L.w("Couldn't read the stream info from Firebase.");
}
});
return mediaStreams;
}
}
公共类FirebaseManager{
专用静态最终字符串DB_REF=“mainframeradio”;
私有静态最终字符串STREAM\u REF=“streams”;
公共静态列表getMediaStreams(上下文){
最终列表mediaStreams=新的ArrayList();
FirebaseDatabase db=FirebaseDatabase.getInstance();
DatabaseReference dbRef=db.getReference(STREAM_REF);
dbRef.addValueEventListener(新的ValueEventListener(){
@凌驾
公共void onDataChange(DataSnapshot DataSnapshot){
Map streams=(Map)dataSnapshot.getValue();
如果(!streams.isEmpty()){
for(对象流:streams.values()){
字符串协议=(字符串)((映射)流).get(“协议”);
字符串主机=(字符串)((映射)流).get(“主机”);
int port=(int)((Map)stream.get(“port”);
字符串媒体=(字符串)((映射)流).get(“媒体”);
字符串元数据=(字符串)((映射)流).get(“元数据”);
String streamName=(String)((Map)stream.get(“streamName”);
MediaStream MediaStream=新的MediaStream(协议、主机、端口、媒体、元数据、流名称);
添加(mediaStream);
}
}否则{
L.d(“在服务器上找不到媒体流”);
}
}
@凌驾
已取消的公共void(DatabaseError DatabaseError){
L.w(“无法从Firebase读取流信息。”);
}
});
返回媒体流;
}
}
问题是事件不会从我调用它的活动中触发
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_player);
// Set components.
this.playerView = findViewById(R.id.playerView);
this.songTitleTextView = findViewById(R.id.songTitleTextView);
this.albumArt = findViewById(R.id.albumArt);
// Hide both the navigation and status bar (immersive).
ViewManager.setFullscreenImmersive(getWindow());
List<MediaStream> mediaStreams = FirebaseManager.getMediaStreams(this);
System.out.print(mediaStreams);
}
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u播放器);
//设置组件。
this.playerView=findviewbyd(R.id.playerView);
this.songTitleTextView=findviewbyd(R.id.songTitleTextView);
this.albumArt=findViewById(R.id.albumArt);
//隐藏导航栏和状态栏(沉浸式)。
setFullscreenImmersive(getWindow());
List mediaStreams=FirebaseManager.getMediaStreams(this);
系统输出打印(mediaStreams);
}
我只想从firebase检索数据。这是数据库
如有任何帮助,将不胜感激。请尝试以下方法检索数据:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("streams");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
String hosts=datas.child("host").getValue().toString();
String medias=datas.child("media").getValue().toString();
String metadata=datas.child("metadata").getValue().toString();
String ports=datas.child("port").getValue().toString();
String protocol=datas.child("protocol").getValue().toString();
String steamname=datas.child("streamName").getValue().toString();
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
datasnapshot是
流
,然后您将能够在子0
中迭代并获取数据尝试以下操作以检索数据:
DatabaseReference reference = FirebaseDatabase.getInstance().getReference("streams");
reference.addListenerForSingleValueEvent(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
String hosts=datas.child("host").getValue().toString();
String medias=datas.child("media").getValue().toString();
String metadata=datas.child("metadata").getValue().toString();
String ports=datas.child("port").getValue().toString();
String protocol=datas.child("protocol").getValue().toString();
String steamname=datas.child("streamName").getValue().toString();
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
datasnapshot是
streams
,然后您将能够在子0
中迭代并获取数据谢谢,将尝试并让您知道。我在LogCatDatabaseError上收到一个数据库错误:权限被拒绝
目前没有。我将更改并重试。谢谢,我将尝试并让您知道。我在LogCat上收到一个数据库错误DatabaseError:Permission denied
目前没有。我将更改它并重试。