我正在开发一个项目，我正在使用Realm数据库和Firebase和RxJava 2.在我的项目中，我有用户活动，它将列出存储在Firebase数据库中的所有注册用户。此外，我必须存储所有注册用户进入Realm数据库（如果Internet不可用，请注册）。因此，每当用户启动活动时，我的observable将逐个运行并获取所有注册用户并将它们存储在Realm数据库中，并且当observable完成时，数据将填充在Realm Database的recyclerview上。这是我的代码
class AllUsers : AppCompatActivity(){
private var recyclers : RecyclerView ?= null
private var toolbars : Toolbar ?= null
private var toolbar_text : TextView ?= null
private var userAdapter : UserAdapter ?= null
private var userModelList : ArrayList<RequestPojo> ?= null
private var databaseReference : DatabaseReference ?= null
private var compositeDisposable : CompositeDisposable ?= null
private var firebaseAuth : FirebaseAuth ?= null
private var currentUserUid : String ?= null
private var realm : Realm?= null
private var requestController : RequestsController ?= null
private var suggestedFriendsController : SuggestedFriendsController ?= null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.allusers)
initialize()
}
private fun initialize(){
compositeDisposable = CompositeDisposable()
userModelList = ArrayList()
toolbars = findViewById(R.id.toolbar)
recyclers = findViewById(R.id.recycler)
toolbar_text = toolbars?.findViewById(R.id.toolbar_text1)
toolbar_text?.visibility = View.VISIBLE
toolbar_text?.text = "Users"
setSupportActionBar(toolbars)
supportActionBar?.setDisplayHomeAsUpEnabled(true)
getSupportActionBar()?.setHomeButtonEnabled(true)
userAdapter = UserAdapter(this,userModelList)
recyclers?.setHasFixedSize(true)
var recyclerlayoutmanager = LinearLayoutManager(this)
recyclers?.setLayoutManager(recyclerlayoutmanager)
val dividerItemDecoration = DividerItemDecoration(recyclers?.getContext(),
recyclerlayoutmanager.orientation)
recyclers?.addItemDecoration(dividerItemDecoration)
recyclers?.itemAnimator = DefaultItemAnimator()
recyclers?.setAdapter(userAdapter)
firebaseAuth = FirebaseAuth.getInstance()
currentUserUid = firebaseAuth?.currentUser?.uid
databaseReference = FirebaseDatabase.getInstance().reference
databaseReference?.keepSynced(true)
realm = Realm.getDefaultInstance()
requestController = RequestsController()
suggestedFriendsController = SuggestedFriendsController()
}
override fun onStart() {
super.onStart()
loadUsersFromFirebase()
populateDataFromRealm()
}
fun populateDataFromRealm(){
suggestedFriendsController?.getAllAsync()
?.subscribe({
t: RealmSuggestedFriends? -> var requestPojo = RequestPojo()
requestPojo?.email = t?.friendEmail
requestPojo?.image = t?.friendImage
requestPojo?.name = t?.friendName
requestPojo?.status = t?.friendStatus
requestPojo?.thumb_image = t?.friendThumbImage
requestPojo?.uid = t?.friendUid
userAdapter?.addData(requestPojo)
},{
t: Throwable? -> t?.printStackTrace()
},{
},{
t: Disposable? ->compositeDisposable?.add(t!!)
})
}
fun loadUsersFromFirebase(){
Observable.create<DataSnapshot>{ emitter ->
databaseReference
?.child("Users")
?.addChildEventListener(object : ChildEventListener{
override fun onCancelled(p0: DatabaseError?) {}
override fun onChildMoved(p0: DataSnapshot?, p1: String?) {}
override fun onChildChanged(p0: DataSnapshot?, p1: String?) {}
override fun onChildAdded(p0: DataSnapshot?, p1: String?) {
if(!emitter.isDisposed){
if (!p0?.key?.equals(currentUserUid)!!){
emitter.onNext(p0)
}
}
}
override fun onChildRemoved(p0: DataSnapshot?) {}
})
}.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(object : Observer<DataSnapshot>{
override fun onComplete() {}
override fun onNext(t: DataSnapshot) {
val userModel = t.getValue(RequestPojo::class.java)
userModel?.uid = t.key
suggestedFriendsController?.addSuggestedFriends(userModel)
}
override fun onSubscribe(d: Disposable) {
compositeDisposable?.add(d)
}
override fun onError(e: Throwable) {
e.printStackTrace()
}
})
}
private fun showMessage(message : String?) {
Toast.makeText(this@AllUsers,message,Toast.LENGTH_SHORT).show()
}
override fun onRestart() {
super.onRestart()
userModelList?.clear()
userAdapter?.notifyDataSetChanged()
}
override fun onBackPressed() {
super.onBackPressed()
finish()
}
override fun onStop() {
super.onStop()
compositeDisposable?.clear()
}
override fun onDestroy() {
super.onDestroy()
realm?.close()
}
}
这是我的Realm Controller，它将涵盖所有存储，检索和更新数据的Realm方法。
class SuggestedFriendsController {
fun addSuggestedFriends(requestPojo: RequestPojo?) {
Realm.getDefaultInstance().use { r->
r?.executeTransaction { realm ->
val realmFriends = RealmSuggestedFriends()
realmFriends.friendEmail = requestPojo?.email
realmFriends.friendImage = requestPojo?.image
realmFriends.friendName = requestPojo?.name
realmFriends.friendStatus = requestPojo?.status
realmFriends.friendThumbImage = requestPojo?.thumb_image
realmFriends.friendUid = requestPojo?.uid
realmFriends.requestSent = "No"
realm.insertOrUpdate(realmFriends)
}
}
}
fun getSuggestedFriendSync(realm : Realm?,uid : String?): RealmSuggestedFriends? =
realm?.where(RealmSuggestedFriends::class.java)?.equalTo("friendUid",uid)?.findFirst()
fun getRequestStateAsync(uid: String?) =
Observable.create<String> { emitter ->
val real = Realm.getDefaultInstance()
try{
val res = real?.where(RealmSuggestedFriends::class.java)
?.equalTo("friendUid", uid)
?.findFirst()
emitter.onNext(res?.requestSent!!)
emitter.onComplete()
}catch(e : Exception){
emitter.onError(Throwable("read failed"))
}
finally {
real?.close()
}
}.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
fun getAllAsync() = Observable.create<List<RealmSuggestedFriends>> { emitter ->
Realm.getDefaultInstance().use { realm ->
val results = realm?.where(RealmSuggestedFriends::class.java)
?.findAll()
emitter.onNext(realm?.copyFromRealm(results)!!)
}
}.flatMapIterable { list -> list }
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
fun updateSuggestedFriendAsync(uid: String?, request_type: String?) =
Single.create<String>{emitter ->
Realm.getDefaultInstance().use { realm ->
try {
realm?.beginTransaction()
var suggested = realm.where(RealmSuggestedFriends::class.java)
.equalTo("friendUid", uid)
.findFirst()!!
suggested.requestSent = request_type
var d = realm.copyToRealmOrUpdate(suggested)
realm?.commitTransaction()
emitter.onSuccess(d?.requestSent!!)
}catch (e : Exception){
emitter.onError(Throwable(e.message))
e.printStackTrace()
}
}
}
.subscribeOn(AndroidSchedulers.mainThread())
}
现在每当我开始我的活动时，我的observable将运行并从Firebase获取每个用户并将它们存储在Realm数据库中。
2还有更好的方法可以将我的Realm数据库与Firebase服务器同步。
请建议我......提前谢谢。