Cache Network data using RX

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Rxjava is responsive programming, which is widely used when processing network data asynchronously.
We can also use some Rx features to gracefully cache network data.

Cache mode: Read the database, display, request data, store to the database, and then update the page.

Using the standard combination of DAGGER2+RETROFIT+RX, let me explain how to use it.

GitHub

1. Framework

Regular items, including jump caches and non-cached pages, load data for 3 seconds of delay in order to simulate a slow environment.

 Public  class mainactivity extends appcompatactivity {    @Override    protected void onCreate(Bundle savedinstancestate) {Super. OnCreate (Savedinstancestate);    Setcontentview (R.layout.activity_main); }//Jump no cache     Public void Gotonocache(View view) {StartActivity (NewIntent ( This, Nocacheactivity.class)); }//jump with cache     Public void Gotocache(View view) {StartActivity (NewIntent ( This, Cacheactivity.class)); }}

2. No cache

Dependency Injection three key parts, Application/component/module.

public   class  rcapplication  extends  application     { private  apicomponent mapicomponent;  @Override  public  void  oncreate         () {super . OnCreate (); Mapicomponent = Daggerapicomponent.builder (). Apimodule (new  apiModule (
    
     this )). Build (); } 
     public  apicomponent 
     getapicomponent  () {
     
      return  mapicomponent; }}
     
    

@Singleton@Component(modules = ApiModule.class)publicinterface ApiComponent {    void inject(NocacheActivity activity);    void inject(CacheActivity activity);}

@Module Public  class apimodule {    PrivateApplication mapplication; Public Apimodule(Application application)    {mapplication = Application; }@Provides    @Singleton     PublicApplicationprovideapplication() {returnMapplication; }@Provides    @SingletonGithubclient providegithubclient () {return NewGithubclient (); }@ProvidesObservablerepodb Provideobservablerepodb () {return NewObservablerepodb (mapplication); }}

The module provides application information, GitHub's network request, database.
@Singleton represents a singleton pattern, and all injections have an instance.

page, display the list information using Recyclerview, and display the ProgressBar at load time.

/** * No cache activity * <p> * Created by Wangchenlong on 16/1/18. * * Public  class nocacheactivity extends Activity {    @Bind(r.id.nocache_rv_list) Recyclerview mrvlist;@Bind(r.id.nocache_pb_progress) ProgressBar mpbprogress;@InjectApplication mapplication;@InjectGithubclient mgithubclient;PrivateListAdapter Mlistadapter;@Override protected void onCreate(Bundle savedinstancestate) {Super. OnCreate (Savedinstancestate);        Setcontentview (R.layout.activity_nocache); Butterknife.bind ( This); ((rcapplication) getapplication ()). Getapicomponent (). Inject ( This); Linearlayoutmanager LayoutManager =NewLinearlayoutmanager (mapplication);        Mrvlist.setlayoutmanager (LayoutManager); Mlistadapter =NewListAdapter ();    Mrvlist.setadapter (Mlistadapter); }@Override protected void Onresume() {Super. Onresume ();//Delay 3 seconds, simulation effectMgithubclient.getrepos ("Spikeking"). Delay (3, timeunit.seconds). Subscribeon (Schedulers.io ()). Observeon (Androidschedulers.mainthread ()) . Subscribe ( This:: Onsuccess, This:: OnError);    Mpbprogress.setvisibility (view.visible); }Private void onsuccess(arraylist<repo> repos)        {Mlistadapter.setrepos (repos);    Mpbprogress.setvisibility (view.invisible); }Private void OnError(Throwable throwable)    {mpbprogress.setvisibility (view.invisible); }}

By observing, it can be found that prolonged display of white screen will degrade the user experience. Let me take a look at the cache mode.

3. Caching

Cache mode: Read the database, display, request data, store to the database, and then update the page.
It is recommended to use a script to generate a database processing class, using the method reference, to automatically generate DBHelper scripts .

Home page logic.

 Public  class cacheactivity extends Activity {    @Bind(r.id.cache_rv_list) Recyclerview mrvlist;//List    @Bind(R.id.cache_srl_swipe) Swiperefreshlayout Msrlswipe;//Refresh    @InjectApplication mapplication;@InjectObservablerepodb Mrepodb;@InjectGithubclient mgithubclient;PrivateListAdapter Mlistadapter;//Recyclerview Adapter    @Override protected void onCreate(Bundle savedinstancestate) {Super. OnCreate (Savedinstancestate);        Setcontentview (R.layout.activity_cache); Butterknife.bind ( This);//Injection class((rcapplication) getapplication ()). Getapicomponent (). Inject ( This); Linearlayoutmanager LayoutManager =NewLinearlayoutmanager (mapplication);        Mrvlist.setlayoutmanager (LayoutManager); Mlistadapter =NewListAdapter ();        Mrvlist.setadapter (Mlistadapter); Msrlswipe.setonrefreshlistener ( This:: Fetchupdates); }@Override protected void Onresume() {Super. Onresume (); Mrepodb.getobservable (). Subscribeon (Schedulers.io ()). Observeon (Androidschedulers.mainthrea D ()). Subscribe ( This:: SetData);        Fetchupdates (); Toast.maketext (Mapplication,"Updating", Toast.length_short). Show (); }//Set data, update completion will call    Private void SetData(arraylist<repo> repos)        {Mlistadapter.setrepos (repos); Toast.maketext (Mapplication,"Update Complete", Toast.length_short). Show (); }Private void fetchupdates() {//Delay 3 seconds, simulation effectMgithubclient.getrepos ("Spikeking"). Delay (3, timeunit.seconds). Subscribeon (Schedulers.io ()). Observeon (Androidschedulers.mainthread ()) . Subscribe (Mrepodb::insertrepolist, This:: Fetcherror, This:: FetchComplete); }Private void Fetcherror(Throwable throwable) {msrlswipe.setrefreshing (false); }Private void FetchComplete() {msrlswipe.setrefreshing (false); }}

Observer for the database

/** * Redo Viewer * <p> * Created by Wangchenlong on 16/1/18. */ Public  class observablerepodb {    PrivatePublishsubject<arraylist<repo>> Mpublishsubject;//Post a theme    PrivateRepodbhelper Mdbhelper;//Database     Public Observablerepodb(Context context) {Mdbhelper =NewRepodbhelper (context);    Mpublishsubject = Publishsubject.create (); }//Return to viewer     PublicObservable<arraylist<repo>>getobservable() {observable<arraylist<repo>> firstobservable = observable.fromcallable ( This:: Getrepolist);returnFirstobservable.concatwith (Mpublishsubject);//Connection Publishing topic}//Get data from the database    PrivateArraylist<repo>getrepolist() {mdbhelper.openforread (); arraylist<repo> repos =NewArraylist<> (); Cursor C = Mdbhelper.getallrepo ();if(!c.movetofirst ()) {returnRepos//return null} do {//Add DataRepos.add (NewRepo (C.getstring (repodbhelper.repo_id_column_position), c.getstring (repodbhelper.re po_name_column_position), c.getstring (repodbhelper.repo_description_column_position),NewRepo.owner (C.getstring (repodbhelper.repo_owner_column_position),"","",""))); } while(C.movetonext ());        C.close (); Mdbhelper.close ();returnRepos }//Insert Repo list     Public void insertrepolist(arraylist<repo> repos)        {Mdbhelper.open (); Mdbhelper.removeallrepo (); for(Repo Repo:repos) {Mdbhelper.addrepo (Repo.getid (), Repo.getname (), Rep        O.getdescription (), Repo.getowner (). GetLogin ());        } mdbhelper.close (); Mpublishsubject.onnext (repos);//Will call Update data}}

This section is the key to implementing a network request to synchronously insert the database and update the page.
Association Publishsubject, after the insert data is complete, invokes the binding observer and updates the page.
That is . Concatwith (Mpublishsubject) and mpublishsubject.onnext (repos).

Rx is really elegant in dealing with network requests and deserves the perfect person to use.

OK, that ' s all! Enjoy it.

Cache Network data using RX