Androidアプリ開発からみた RxJavaの使いどころ

"OESPJEΞϓϦ։ൃ͔ΒΈͨ 3Y+BWBͷ࢖͍Ͳ͜Ζ ++6($$$4QSJOH /BPLJ.PSJPLB

ΤϯδχΞྺ೥໨ $ݴޠΛ೥΄Ͳɺޙ͸΄ͱΜͲ+BWB ࠷ۙ͸"OEPSJEJ04ΞϓϦ։ൃ ੝Ԭঘه !O@NPSJPLB IUUQTHJUIVCDPNONPSJPLB "CPVU.F ϑϦϡʔגࣜձࣾۈ຿ژ౎ࡏॅ

ࢲͷ3Y+BWB΁ͷϞνϕʔγϣϯ w ؔ਺ܕzతzͳॲཧͷѻ͍͕Մೳ খ͍͞ॲཧΛ૊Έ߹Θͤͯେ͖ͳॲཧΛهड़͍ͯ͘͠ +BWBͰهड़ग़དྷͯ΄Ͳྑ͍όϥϯεײ֮ w ࢖ͬͯΈΔͱ৭ʑͱ৽͍͠ൃݟ͕͋Δ qBU.BQ[JQDPNCJOF-BUFTUͳͲͷར༻

ར༻͍ͯ͠Δόʔδϣϯ w +%,@ w 3Y+BWB w 4QSJOH#PPU#6*-%4/"14)05 w 3FBDUPSɿ#6*-%4/"14)05

ΞδΣϯμ w 3Y+BWBͷ֓ཁ w 3Y+BWBͷجຊ w "OESPJEΞϓϦͰͷར༻ʹ͍ͭͯ w αʔόαΠυͰͷར༻ʹ͍ͭͯ w
·ͱΊ

w +BWB7.্Ͱಈ࡞͢Δ؍ଌՄೳ 0CTFSWBCMF ͳ࣌ܥྻσʔλ Λ༻͍ͨɺඇಉظͳΠϕϯτϕʔεͷϓϩάϥϛϯά ϦΞΫςΟ ϒϓϩάϥϛϯά ΛՄೳʹ͢ΔϥΠϒϥϦ w +BWBҎ্Ͱར༻Մೳ
w ݱঢ়ͷϝΠϯ͸3Y+BWBܥ w 3Y+BWB3FBDUJWF&YUFOTJPOT 3FBDUJWF4USFBNT 8IBU`T3Y+BWBʁ

ϦΞΫςΟϒϓϩάϥϛϯάᶃ w ͋ΔσʔλετϦʔϜʹରͯ͠ ͍ͭ͘Δ͔Θ͔Βͳ͍ σʔ λʹ൓ԠతʹϓϩάϥϛϯάΛߦ͏͜ͱ σʔλ ࣌ܥྻʹԊͬͨྲྀΕετϦʔϜ σʔλ ʜ

ϦΞΫςΟϒϓϩάϥϛϯάᶄ w 3Y+BWBʹ͓͍ͯ͸+BWBΠϯελϯεͷ͕ͭͭσʔλ 4USFBN"1*ͱಉ͡ " # $ 4USJOHσʔλ " "
" # $ # # $ $ # $ " # $ " # $ -JTUσʔλ

ϦΞΫςΟϒϓϩάϥϛϯάᶅ w σʔλετϦʔϜͷੜ੒΍ɺม׵ɺ߹੒Λߦ͏ w ετϦʔϜ͔ΒདྷΔσʔλΛड͚औͬͨॲཧ ߪಡ Λهࡌ͢Δ " # $
Πϕϯτ " " Πϕϯτ ʜ B C D B B 4USJOH ͂ TUP-PXFS$BTF ม׵ 4ZTUFNPVUQSJOUMO ߪಡ B C D ʜ

w ϚΠΫϩιϑτࣾʹΑͬͯఏএ͞Εͨɺෳࡶͳඇಉظॲཧ΍Πϕ ϯτॲཧɺ͕࣌ؒؔ܎͢ΔॲཧͳͲΛهड़Ͱ͖Δ"1*܊ͷ࢓༷ w /&5΍+4ͳͲ֤छ࣮૷͕͋Δ w େ͖͍࢓༷ 3FBDUJWF&YUFOTJPOT 3Y IUUQTHJUIVCDPN3FBDUJWF&YUFOTJPOT

w ϊϯϒϩοΩϯάͳ#BDL1SFTTVSFΛ༻͍ͨඇಉظετϦʔϜॲཧͷ࢓༷ w ͭͷΠϯλʔϑΣʔεఆٛͷఏڙ 1VCMJTIFS 4VCTDSJCFS 4VCTDSJQUJPO 1SPDFTTPS w 5FTU4VJUFͷఏڙ
5$, w খ͍͞࢓༷ 3FBDUJWF4USFBNT

3FBDUJWF4USFBNTΠϯλʔϑΣʔε Publisher public void subscribe(Subscriber<? super T> s); Subscriber public
void onSubscribe(Subscription s); public void onNext(T t); public void onError(Throwable t); public void onComplete(); /EBUBSFRVFTU /EBUBTUSFBNJOH TVCTDSJCF Subscription public void request(long n); public void cancel(); 1VCMJTIFS͕σʔλΛྲྀ͠4VCTDSJCFS͕σʔλΛड͚औΔॲཧ͕جຊ Processor public interface Processor<T, R> extends Subscriber<T>, Publisher<R> { }

#BDL1SFTTVSF w ड৴ଆ͔Βૹ৴ଆ΁ͷσʔλϑϩʔ੍ޚ w ॲཧ͕ऴΘͬͨ͜ͱΛ఻͑ͯ࣍ͷσʔλΛऔಘ͢Δ w ૹ৴ଆͷσʔλੜ੒ͷํ͕଎͍৔߹͸4USBUFHZʹैͬͨॲཧ࣮ࢪ w ࿈݁΍߹੒΋Մೳ ॲཧ͖ͬͨ͠ͷͰ࣍Լ͍͞
data 0, #BDL1SFTTVSF 4USBUFHZ #6''&3 %301 -"5&45 &3303 /0/& Publisher Subscriber

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3Y+BWBͷίΞ 'MPXBCMF0CTFSWBCMF

'MPXBCMF0CTFSWBCMFͱ͸Կ͔ʁ w σʔλͷετϦʔϜΛੜ࢈ͯ͠ɺอ࣋͢ΔೖΕ෺ͷΑ͏ͳ΋ͷɻ ߪಡ TVCTDSJCF Մೳ 'MPXBCMF͸1VCMJTIFSΛ࣮૷ɺ#BDL1SFTTVSF੍ޚ͋Γɹ 0CTFSWBCMF͸#BDL1SFTTVSF੍ޚͳ͠ɻύϑΥʔϚϯε͸ྑ͍ w ͭͷঢ়ଶΛߪಡऀʹ఻͑Δɹ
4VCTDSJCF/FYU$PNQMFUF&SSPS w ͭͷੑ࣭Λ࣋ͭ )PU $PME

̐ͭͷঢ়ଶ w 4VCTDSJCF͸௨஌ͷ४උ͕ग़དྷͨঢ়ଶ w /FYU͸σʔλ͕ྲྀΕ͍ͯΔঢ়ଶɻσʔλ಺༰͕ϋϯυϦϯά͞ΕΔ w $PNQMFUF͸ਖ਼ৗऴྃɻετϦʔϜʹσʔλ͕ྲྀΕͳ͘ͳΔ w &SSPS͸ҟৗऴྃɻετϦʔϜʹσʔλ͸ྲྀΕͳ͘ͳΔ OFYU
OFYU OFYU OFYU OFYU DPNQMFUF OFYU OFYU FSSPS TVCTDSJCF TVCTDSJCF

ߪಡॲཧ Flowable.just("1", "2", "3", "4") .subscribe(new Subscriber<String>() { public void
onSubscribe(Subscription subscription) { subscription.request(Long.MAX_VALUE); System.out.println("subscribed"); } public void onNext(String s) { int num = Integer.parseInt(s); System.out.println(num); } public void onError(Throwable throwable) { System.out.println("error"); } public void onComplete() { System.out.println("completed"); } }); TVCTDSJCFE DPNQMFUFE SFTVMU ੜ੒ ᶃ։࢝ ᶄσʔλऔಘ ᶅਖ਼ৗऴྃ

ߪಡॲཧ ؔ਺ܕ*OUFSGBDF +BWB Flowable.just("1", "2", "3", "4")  .subscribe(s -> { 
int num = Integer.parseInt(s);  System.out.println(num);  }, throwable -> {  System.out.println("error : " + throwable.getMessage());  }); SFTVMU /FYUॲཧϋϯυϦϯά Τϥʔॲཧ

ߪಡॲཧ ؔ਺ܕ*OUFSGBDF +BWB public final Disposable subscribe(Consumer<? super T> onNext,
Consumer<? super Throwable> onError, Action onComplete, Consumer<? super Subscription> onSubscribe) { LambdaSubscriber<T> ls = new LambdaSubscriber( onNext, onError, onComplete, onSubscribe); this.subscribe((FlowableSubscriber)ls); return ls; } ಺෦తʹ4VCTDSJCFSΛ࡞੒ͯ͠ॲཧ͍ͯ͠Δ

'MPXBCMFͱ+BWB4USFBN"1*ͱͷҧ͍ w 'MPXBCMF͸࠶ར༻Մೳ w 'MPXBCMF͸࣮ߦ5ISFBEΛॲཧ్தͰ੾Γସ͑Մೳ w ྫ֎ͷѻ͍ 4USFBN"1*͸֎ଆʹ఻ൖ͢Δ 'MPXBCMF͸಺෦Ͱॲཧ͢Δ͜ͱ͕Մೳ

4USFBN"1* ࠶ར༻ෆՄ Stream<String> st = Arrays.asList("1", "2", "3", "4").stream();  st.forEach(s
-> {  System.out.println(s);  }); System.out.println(“next");   st.forEach(s -> {  System.out.println(s);  }); OFYU KBWBMBOH*MMFHBM4UBUF&YDFQUJPOTUSFBNIBTBMSFBEZCFFOPQFSBUFEVQPOPSDMPTFE BUKBWBVUJMTUSFBN"CTUSBDU1JQFMJOFJOJU "CTUSBDU1JQFMJOFKBWB ʜ SFTVMU

'MPXBCMF ࠶ར༻Մೳ Flowable<String> flowable = Flowable.just("1", "2", "3", "4"); flowable.subscribe(s
-> { System.out.println(s); }); System.out.println("next"); flowable.subscribe(s -> { System.out.println(s); }); OFYU SFTVMU

'MPXBCMF ྫ֎ͷѻ͍ Flowable.just("1", "2", "three", “4") .map(Integer::parseInt)  .subscribe(num -> { 
System.out.println(num);  }  , throwable -> {  System.out.println("error : " + throwable.getMessage());  }); FSSPS'PSJOQVUTUSJOHUISFF SFTVMU /VNCFS'PSNBU&YDFQUJPO Τϥʔऴྃ

'MPXBCMF ࣮ߦ5ISFBE੍ޚ Flowable.just("a", "b", "c", "d") .map(s -> { System.out.println(Thread.currentThread().getName()
+ " : " + s); return s.toUpperCase(); }) .subscribeOn(Schedulers.newThread()) .observeOn(Schedulers.computation()) .blockingSubscribe(s -> { System.out.println(Thread.currentThread().getName() + " : " + s); }); 3Y/FX5ISFBE4DIFEVMFSB 3Y/FX5ISFBE4DIFEVMFSC 3Y/FX5ISFBE4DIFEVMFSD 3Y/FX5ISFBE4DIFEVMFSE 3Y$PNQVUBUJPO5ISFBE1PPM" 3Y$PNQVUBUJPO5ISFBE1PPM# 3Y$PNQVUBUJPO5ISFBE1PPM$ 3Y$PNQVUBUJPO5ISFBE1PPM% SFTVMU TVCTDSJCF0O'MPXBCMF0CTFSWFCMFॲཧͷ࣮ߦεϨου PCTFSWF0OͦΕҎ߱ͷ࣮ߦεϨου ݩͷ'MPXBCMFͷ࣮ߦεϨουΛࢦఆ ͜͜Ҏ߱ͷ࣮ߦεϨουΛࢦఆ

ม׵ॲཧ NBQ Flowable.just(1, 2, 3, 4) .map(num -> num *
num)  .subscribe(num -> {  System.out.println(num);  }); SFTVMU NBQ͸ετϦʔϜ಺ͷσʔλͦͷ΋ͷΛม׵͢Δ

ม׵ॲཧ qBU.BQ Flowable.just(1, 2) .flatMap(v -> { // new flowable
return Flowable.just(v, 2 * v); }) .subscribe(System.out::println); SFTVMU qBU.BQ͸σʔλ͔Β'MPXBCMFΛ࡞੒ͯ͠ ࠷ऴతʹl'MPXBCMFΛऔΓ෷ͬͯzετϦʔϜΛߏங͢Δ " 'MPXBCMF " " # $ 'MPXBCMF # # 'MPXBCMF $ $ " # $ " # $

ม׵ॲཧ qBU.BQ public Flowable<Integer> square(int v) { return Flowable.just(v).map(w ->
w * w); } public Flowable<Integer> twin(int v) { return Flowable.just(v, v); }; Flowable<Integer> f1 = Flowable.just(1,2); Flowable<Integer> f2 = f1.flatMap(v -> square(v)); Flowable<Integer> f3 = f2.flatMap(v -> twin(v)); f1.subscribe(v1 -> System.out.println("f1 : " + v1)); f2.subscribe(v1 -> System.out.println("f2 : " + v1)); f3.subscribe(v1 -> System.out.println("f3 : " + v1)); G G G G G G G G SFTVMU 'MPXBCMF͸ʮ͋Δঢ়ଶʯͷσʔλετ ϦʔϜΛఆٛ͠ ม਺ͷΑ͏ʹѻ͑Δ

w ετϦʔϜͷੜ੒ॲཧ KVTUGSPN$BMMBCMFGSPN"SSBZͳͲ w σʔλม׵ॲཧ pMUFSNBQqBU.BQͳͲ w ߹੒ॲཧ NFSHF[JQDPNCJOF-BUFTUͳͲ w
෭࡞༻ ߪಡऀ΁ͷ௨஌ͱ͸ผͷॲཧ EP0O4VCTDSJCFEP0O/FYUEP0O$PNQMFUFͳͲ ΦϖϨʔλͷछผ ม׵ ੜ੒ TVCTDSJCF ߹੒ ෭࡞༻ ੜ੒ ม׵

)PU$PME

)PU$PMEͱ͍͏ੑ࣭ w ੜ࢈ऀ 'MPXBCMF0CTFSWBCMF ͷੑ࣭ w $PME͸ճ͝ͱͷར༻ ߪಡ͞Εͳ͍ͱՔಇͤͣɺߪಡ͝ͱʹ৽͍͠ετϦʔϜ͕࠶ੜ͞ΕΔ 'MPXBCMF0CTFSWBCMF͸େମ$PME ಈըͰݴ͏ͱ:PV5VCFͷ࠶ੜͷΑ͏ͳײ͡
w )PU͸ܧଓతͳར༻ ετϦʔϜ͔Β஋ΛৗʹਨΕྲྀ͢ ෳ਺ͷߪಡऀʹಉ࣌ʹσʔλΛ௨஌͢Δ ಈըͰݴ͏ͱςϨϏͷΑ͏ͳײ͡

3Y+BWBͷ)PU$PME OFYU OFYU OFYU $PME 4VCTDSJCFS OFYU OFYU OFYU $PMEͷετϦʔϜ͸ߪಡऀ͝ͱʹ࠶౓࠶ੜ͞ΕΔΑ͏ͳΠϝʔδ
4VCTDSJCFS

3Y+BWBͷ)PU$PME OFYU OFYU OFYU )PU )PUͷߪಡ͸ߪಡऀ͕ਨΕྲྀ͞ΕΔσʔλΛͦΕͧΕಡΉΠϝʔδ ਨΕྲྀ͠ 4VCTDSJCFS 4VCTDSJCFS

)PUͳੜ࢈ऀ 1SPDFTTPS PublishProcessor<Integer> processor = PublishProcessor.create(); processor.subscribe(num -> { System.out.println("number1
: " + num); }); processor.subscribe(num -> { System.out.println("number2 : " + num); }); processor.onNext(1); processor.onNext(2); processor.onNext(3); processor.onNext(4); OVNCFS OVNCFS OVNCFS OVNCFS OVNCFS OVNCFS OVNCFS OVNCFS SFTVMU ߪಡొ࿥ ෳ਺ొ࿥Մೳ σʔλొ࿥ 1SPDFTTPSʹ͸ड͚ޱ΋༻ҙ͞Ε͍ͯΔ

·ͱΊ

ϢʔβʔΞΫγϣϯͰͷ׆༻ྫ RxTextView.textChanges(a1Text) .subscribe(e -> { b1Text.setText( “” + (Long.parseLong(e.text) +
Long.parseLong(a2Text.getText()))); }); RxView.clicks(button) .debounce(1L, TimeUnit.SECONDS) .subscribe(x -> { // ੍ݶ͞Εͨೖྗ }) 3Y+BWBͷαϯϓϧͱͯ͠ग़ͯདྷΔ͕ ඞਢͱ͍͏Θ͚Ͱ΋ͳ͍ ݸਓతҙݟ

"OESPJEͰ3Y+BWB͕ ࠷΋࢖ΘΕ͍Δ৔໘ ωοτϫʔΫ௨৴

લఏͱͯ͠"OESPJEΞϓϦͷ੍ݶ w ϘλϯλοϓͰը໘ΛϩοΫ͠ͳ͍͜ͱ͕ਪ঑͞ΕΔ w ը໘ૢ࡞͸6*εϨου ϝΠϯεϨου ͰͷΈ࣮ࢪՄೳ w ωοτϫʔΫ௨৴͸6*εϨουʮҎ֎ʯͰ࣮ࢪՄೳ 6*5ISFBE
*05ISFBE 7JFXߋ৽ "1*$BMM

ඪ४ͷ"TZOD5BTL-PBEFSαϯϓϧ public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Bitmap> { //
ActivityͷͲ͔͜ʹ͋ΔϘλϯλοϓίʔυ button.setOnClickListener(new OnSingleClickListener() {  @Override  public void onSingleClick(View view) {  Bundle args = new Bundle(); args.putString("url", url); // ඇಉظॲཧΛґཔ getSupportLoaderManager().initLoader(0, args, this); } }); @Override public void Loader<Bitmap> onCreateLoader(int id, Bundle args) { return new ImageAsyncTaskLoader(this, args.getString("url")); } @Override public void onLoadFinished(Loader<Bitmap> arg0, Bitmap arg1) { imageView.setImageDrawable(new BitmapDrawable(getResources(), bmp)); } } Ϋϥογϡ͢ΔՄೳੑ͋Γ σʔλऔಘґཔ ݁Ռ$BMMCBDLΛड͚ͯ7JFXߋ৽

"TZOD5BTLதʹ"DUJWJUZ͕ফ͑ڈΔ w ωοτϫʔΫ௨৴தʹผͷը໘͕ىಈ͢Δ - ϝϞϦ͕গͳ͍ͱόοΫάϥϯυͷActivity͸kill͞ΕΔ w ωοτϫʔΫ௨৴தʹը໘͕ճస͞ΕΔ - ը໘͕ճస͞ΕΔͱActivity͸࠶࡞੒͞ΕΔ w
جຊతʹʮফ͑Δ͜ͱલఏʹ࡞Δʯͱ͍͏ελϯε

"OESPJEΞϓϦͷωοτϫʔΫ௨৴ w ໰୊ - AsyncTaskॲཧͰ͸ਖ਼࣮͘͠૷͢Δίετ͕ߴ͍ - Callback੍ޚ͕ෳࡶʹͳΓ1 ActivityͰ࢖͑ΔAPIΛ૿΍͠ʹ͍͘ • ཧ૝తͳॲཧ
- ࣮ߦεϨουͷ੍ޚΛ؆୯ʹߦ͍͍ͨ - Activityͷഁغ࣌ʹ͸ߋ৽ॲཧΛࢭΊ͍ͨ - ෳ਺ͷAPIΛݺͼग़͢৔߹ʹ΋͏·͘ॲཧ͍ͨ͠

3Y+BWB 3Y"OESPJE 3Y-JGFDZDMF

3Y+BWBͰ؆ܿʹهࡌ public class MainActivity extends RxActivity { // ActivityͷͲ͔͜ʹ͋ΔϘλϯλοϓίʔυ button.setOnClickListener(()
-> {  Flowable.fromCallable(() -> { return userModel.get(userId); }) .compose(bindToLifecycle()) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(user -> { textView.setText(user.getName())); }); } } Ϣʔβʔ৘ใऔಘ "DUJWJUZ͕ഁغ͞ΕͨΒॲཧΛ΍ΊΔ 5ISFBE੍ޚ 7JFXߋ৽

࠶ར༻ͷͨΊʹ'MPXBCMFʹ͓͖͍ͯͨ͠ public class UserModel { public User get(String userId) { 
…  } } public class UserModel { public Flowable<User> get(String userId) {  …  } } 'MPXBCMFϕʔεͷ໭Γ஋Λ࡞੒

public class MainActivity extends RxActivity { button.setOnClickListener(() -> { userModel.get(userId) 
.flatMap(user -> imageMode.loadBitmap(user.getProfileUrl)) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(bmp -> { imageView.setImageDrawable(new BitmapDrawable(getResources(), bmp)); }); } } ࠶ར༻ɿͭͷॲཧΛ߹੒ͯ݁͠ՌΛऔಘ ม׵࣌ʹՄಡੑ͕ߴ·Δ Ϣʔβʔ৘ใΛऔಘͯ͠ ϓϩϑΟʔϧը૾औಘ

࠶ར༻ɿҰׅऔಘ [JQ public class MainActivity extends RxActivity { button.setOnClickListener(() ->
{ Flowable.zip( userModel.get(userId), imageModel.get(url) )  .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe((user, bmp) -> { textView.setText(user.name); imageView.setImageDrawable(new BitmapDrawable(getResources(), bmp)); }); } } ෳ਺ͷॲཧΛҰؾʹཁٻͯ͠ ݁Ռ͕ͦΖͬͨஈ֊Ͱ7JFXߋ৽

ϦτϥΠ public class MainActivity extends RxActivity { button.setOnClickListener(() -> {
userModel.get(userId)  .flatMap(user -> imageMode.loadBitmap(this.user.profileUrl)) .retry(3, throwable -> { // retryՄ൱ίʔυ return true; }) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(bmp -> { imageView.setImageDrawable(new BitmapDrawable(getResources(), bmp)); }); } } qBU.BQͨ͠ॲཧશମ͕Τϥʔ࣌࠶࣮ߦ͞ΕΔ

3Y+BWB͸ ෳ਺ͷը໘ͷҰׅߋ৽ʹ΋࢖ΘΕΔ

ಉҰσʔλΛࢀর͢Δෳ਺ͷը໘ w ϝϞϦ͕͋Ε͹"DUJWJUZ͕ελοΫ͞Ε͍ͯͯ࢒͍ͬͯΔ w ΠϯελάϥϜͷz͍͍ͶzͳͲ͸ɺλοϓ͞Εͨॠؒʹશը ໘ʹσʔλΛ൓өͤ͞Δඞཁ͕͋Δ IUUQTTIPNBEBOFUXQDPOUFOUVQMPBETTJOHMF5BTLYKQH

1SPDFTTPSΛར༻ͨ͠ߋ৽Πϕϯτϋϒ w 1SPDFTTPSʹྲྀΕΔσʔλΛߪಡ͢Δ͜ͱͰෳ਺ͷ7JFXΛ ߋ৽ग़དྷΔ 1SPDFTTPS 7JFXߋ৽ 7JFXߋ৽ %BUB $IBOHF &WFOU
PO/FYU TVCTDSJCF TVCTDSJCF

w ͭલʹྲྀΕͨσʔλΛอ࣋͢Δ#FIBWJPS1SPDFTTPS w ྫ͑͹࠷৽ͷϩάΠϯϢʔβʔσʔλΛΩϟογϡ͓ͯ͘͠ ͳͲͷ࢖͍ํ͕ग़དྷΔ #FIBWJPS 1SPDFTTPS ৽ن7JFX 7JFXߋ৽ TVCTDSJCF
TVCTDSJCF ࠷৽ͷ݅Λอ࣋ %BUB $IBOHF &WFOU PO/FYU ৽͘͠TVCTDSJCF͞Εͨ΋ͷʹΩϟογϡ͞Εͨ݅Λྲྀ͢ ༷ʑͳ1SPDFTTPS

w "OESPJEಛ༗ͷ໰୊ʹΑΓωοτϫʔΫ௨৴Ͱඞཁ 3Y+BWBΛߴ౓ͳ1SPNJTFతʹར༻ w .PEFM૚ͷ໭Γ஋Λ'MPXBCMFԽ খ͞ͳॲཧΛ߹੒༷ͯ͠ʑͳॲཧΛੜΈग़͢ มߋͷଟ͍ϞόΠϧΞϓϦͰ͸ॏๅ͢Δ "OESPJEΞϓϦ։ൃͰͷ͔͍ͭͲ͜Ζ

·ͱΊ

αʔόαΠυͰͷར༻Ҋ w ϚΠΫϩαʔϏεͰͷ"1*$BMM - ࣮ߦεϨου੍ޚ - Back PressureʹΑΔ੍ޚ - ෳ਺αʔϏεݺͼग़͠ͷ߹੒
- ϦτϥΠͳͲͷ੍ޚ ϑϩϯτ޲͚"1* Ϣʔβʔ৘ใαʔϏε ը૾৘ใαʔϏε "1*$BMM "1*$BMM "1*$BMM Ґஔ৘ใαʔϏε

3FBDUJWF8FC1SPHSBNNJOH

w Ϟσϧ૚ͷॲཧ %#ΞΫηεɺ"1*$BMM ΛετϦʔϜԽ w ίϯτϩʔϥͰϨεϙϯεΛੜ੒͢Δ࣌ʹϒϩοΩϯά͞ ΕΔ Ϟσϧ૚͚ͩϦΞΫςΟϒରԠʁ $POUSPMMFS ετϦʔϜ࡞੒
CMPDLJOH4VCTDSJCF .PEFM CMPDLJOH SFRVFTU SFTQPOTF

w ίϯτϩʔϥͰετϦʔϜΛߪಡ͠ͳ͍ͷͰϊϯϒϩοΩϯάͰॲཧՄೳ - ߴύϑΥʔϚϯε͕ظ଴Ͱ͖Δ - εϨουͷ༗ޮར༻͕ظ଴Ͱ͖Δ w )551ΫΤετͷड͚ޱʹ֤ͯσʔλͷੜ੒΍ग़ྗ·ͰͷzྲྀΕzΛ؆ܿʹ هड़ग़དྷΔ ίϯτϩʔϥ૚ͷϦΞΫςΟϒରԠ
$POUSPMMFS ετϦʔϜ࡞੒ TVCTDSJCF .PEFM 'SBNFXPSL ετϦʔϜ࡞੒ ετϦʔϜ ߹੒ɾม׵

4QSJOH#PPUͰ࣮ݱՄೳ

4QSJOHͰ͸3FBDUPS͕࢖ΘΕΔ w 3YʹӨڹΛड͚ͨϦΞΫςΟϒϥΠϒϥϦ 3Y+BWBͱಉ͡ΦϖϨʔλ΋ଟ਺͋Γ w 3FBDUJWF4USFBNTʹ४ڌ 3Y+BWB 3FBDUPS ରԠ+BWBόʔδϣϯ +BWB
+BWB 0CTFSWBCMFγʔέϯε 'MPXBCMF 'MVY εϨου੍ޚϝιου TVCTDSJCF0O  PCTFSWF0O TVCTDSJCF0O QVCMJTI0O 3Y+BWBͱ3FBDUPSͰେ͖͘ҧ͏ͱ͜Ζ

4QSJOH8FC3FBDUJWFͷαϯϓϧ @GetMapping(value = "/github_user", produces = "application/json") public Flux<GithubUser> githubUser()
{ return httpGet("https://api.github.com/users?slice=1") .flatMapMany(response -> response.bodyToFlux(GithubUser.class)) .take(5); } public Mono<ClientResponse> httpGet(String url) { WebClient client = WebClient.create(url); return client.get().uri("").exchange(); } public class GithubUser { public String login; public String avatar_url; public String toString() { return "[login : " + login + ", avator_url : " + avatar_url + "]"; } } > curl http://localhost/github_user [{"login":"mojombo","avatar_url":"https://avatars3.githubusercontent.com/u/1?v=3"}, {"login":"defunkt","avatar_url":"https://avatars3.githubusercontent.com/u/2?v=3"}, {"login":"pjhyett","avatar_url":"https://avatars3.githubusercontent.com/u/3?v=3"}, {"login":"wycats","avatar_url":"https://avatars3.githubusercontent.com/u/4?v=3"}, {"login":"ezmobius","avatar_url":"https://avatars3.githubusercontent.com/u/5?v=3"}] SFTVMU 'MVYϕʔεͷϨεϙϯε 3FBDUJWF8FC$MJFOU

΋͔ͨ͠͠Βศརͳ࢖͍ํ w σʔλ഑৴੍ޚ - σʔλΛอ࣋͢ΔετϦʔϜ - λΠϛϯάΛ੍ޚ͢ΔΞΫγϣϯετϦʔϜ - 2ͭΛ෼͚ͯετϦʔϜԽͯ͠߹੒͢Δ͜ͱͰෳࡶͳ੍ޚΛ࣮ݱ σʔλετϦʔϜ
ΞΫγϣϯετϦʔϜ ఆظ࣮ߦ΍ඇಉظΠϕϯτ ߹੒ [JQ DPNCJOF-BUFTU σʔλ഑৴੍ޚ

[JQ w ̎ͭҎ্ ͭҎԼ ͷετϦʔϜΛʮ߹੒ʯ͢Δ w σʔλ͕ྲྀΕΔλΠϛϯά͸֤ετϦʔϜͷσʔλ͕ἧͬ ͨͱ͖ [JQ Y
Z lz Y Z " # $ " ߹੒݁Ռ # $

" # $ DPNCJOF-BUFTU w ̎ͭҎ্ ͭҎԼ ͷετϦʔϜΛʮ߹੒ʯ͢Δ w σʔλྲྀΕΔλΠϛϯά͸ετϦʔϜͷͲΕ͔ʹz/FYUz͕ൃߦͨ͞ͱ͖
w /FYU͕ൃߦ͞Εͳ͔ͬͨํ͸લճྲྀͨ͠σʔλ -BUFTU Λ࠶౓ྲྀ͢ DPNCJOF-BUFTU Y Z lz Y Z " ߹੒݁Ռ # # $ $

4FSWFS4FOU&WFOUTͰ߹੒Λ࢖͏ @GetMapping(value = "/stream_data/", produces = "text/event-stream") public Flux<GithubUser> streamData()
{ Flux<Long> interval = Flux.interval(Duration.ofSeconds(1)); Flux<GithubUser> results = httpGet("https://api.github.com/users?slice=1") .flatMapMany(response -> response.bodyToFlux(GithubUser.class)) .take(5); return Flux.zip(interval, results) .map(Tuple2::getT2); } λΠϛϯάΛ͸͔Δ'MVY σʔλΛੜ੒͢Δ'MVY

[JQͨ݁͠Ռ ඵ͝ͱʹ̍ߦ௥Ճ͞Ε͍ͯ͘

ΞδΣϯμ w 3Y+BWBͷ֓ཁ w 3Y+BWBͷجຊ w "OESPJEΞϓϦͰͷར༻ w αʔόαΠυͰͷར༻ʹ͍ͭͯ w
·ͱΊ

࣮ࡍʹͲ͏΍ͬͯಋೖ͔ͨ͠ʁ w "OESPJEΞϓϦʹ೥Ҏ্લʹಋೖ w J04։ൃऀͰϦΞΫςΟϒϓϩάϥϛϯά࣮ફऀ͕νʔϜʹ δϣΠϯͨ͠ͷ͕͖͔͚ͬ w ޱ಄ʹΑΔઆ໌΍13ϨϏϡʔΛ௨ͯ͡νʔϜʹ఻ൖ w ઃܭʹ͍ͭͯ͸τϥΠΞϯυΤϥʔ
Ұੲલ͸Ұॹʹٞ࿦ग़དྷΔਓ͕ډͳ͍ͱಋೖ͠ʹ͍͘ঢ়ଶͩͬͨ

ࠓͳΒಠश͸ՄೳͰ͸ʁ w ʮ3Y+BWBϦΞΫςΟϒϓϩάϥϛϯάʯ͕ૉ੖Β͍͠ w ࣮ࡍʹखΛಈ͔༷ͯ͠ʑͳಈ࡞Λ֬ೝͯ͠ΈΔͷ͕ཧղ΁ͷۙಓ IUUQSYNBSCMFTDPN΋ࢀߟʹ w ઃܭ࿦ͳͲ΋೔ຊޠจݙ͕2JJUBʹͨ͘͞Μ্͕͍ͬͯΔ

3Y+BWBͰؾΛ͚ͭΔ͜ͱ w QVCMJDͳϝιουΛ'MPXBCMF0CTFSWBCMFʹґଘͤͨ͞৔ ߹ͷةݥੑ όʔδϣϯΞοϓ࣌ͷޙํޓ׵ੑͷةݥੑ ଞͷϑϨʔϜϫʔΫ΁ͷ৐Γ׵͑ΒΕͳ͍ةݥੑ

$PODMVTJPO w 3Y+BWB͸ඇಉظͳσʔλετϦʔϜΛॲཧ͢ΔϥΠϒϥϦɻεϨου੍ޚ͕ಛ ௃తͰؔ਺ܕతͳΦϖϨʔλΛଟ࣋ͭ͘ w 3Y+BWBͷ࢖͍ॴɿ"OESPJEΞϓϦͷͷωοτϫʔΫ௨৴ॲཧΛ؆ܿʹهड़ग़དྷ Δ w 8FCϓϩάϥϛϯάʹ͓͍ͯ΋ϦΞΫςΟϒϓϩάϥϛϯά͸ॏཁ౓Λ૿ͯ͠ ͖ͦ͏
w "OESPJEΞϓϦ։ൃҎ֎ͳΒ3FBDUPS͕ྑ͍બ୒ࢶͰ͸ ͨͩ͠೔ຊޠจݙͷଟ͔͞Β3Y+BWBͰษڧ͓ͯ͘͠ͱ͍͏ͷ΋ΞϦͰ͸

ϦΞΫςΟϒϓϩάϥϛϯάͰ ͖ͬͱϓϩάϥϛϯά͕ ΋ͬͱָ͘͠ͳΔ͸ͣʂ

ॕ"OESPJEͰ,PUMJO͕ਖ਼ࣜαϙʔτʂʂ w 3Y+BWB͸,PUMJOͰ΋࢖͑Δ w 3Y,PUMJO΋͋Δ val list = listOf("Alpha", "Beta",
"Gamma", "Delta", "Epsilon") list.toObservable() // extension function for Iterables

ࢀߟจݙ w IUUQOJOKJOLVOIBUFOBCMPHDPNFOUSZJOUSPSYKB ʲ຋༁ʳ͋ͳ͕ͨٻΊ͍ͯͨϦΞΫςΟϒϓϩάϥϛϯάೖ໳ w IUUQPLBQJFTIBUFCMPKQFOUSZ ؔ਺ܕϓϩάϥϚͷͨΊͷ3Yೖ໳ w IUUQRJJUBDPNZVZB@QSFTUPJUFNTGBEEDGD 3Y+BWBʹ೔Ͱೖ໳͠ɺ"OESPJEΞϓϦͷϦετૢ࡞ɺඇಉظॲཧɺมߋ௨஌ͷ՝୊Λղܾͨ͠࿩
w IUUQTCMPHJLBNFOUSJFT 3Y+BWBϦΞΫςΟϒϓϩάϥϛϯάʯ͸4QSJOH3FBDUPSΛษڧ͢Δͷʹ΋໾ʹཱͭॻ੶ w IUUQTHJUIVCDPNKZVLVUZPTQSJOHSFBDUJWFFYBNQMF

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