1400万ユーザーのWebサービスを 15年運用して考える、 Javaである理由

ϑϦϡʔגࣜձࣾླ໦ਅੜ !NBTBP[Jʣ ສϢʔβʔͷ8FCαʔϏεΛ ೥ӡ༻ͯ͠ߟ͑Δɺ  +BWBͰ͋Δཧ༝

w ϑϦϡʔגࣜձࣾ!ژ౎ w ࣾձਓྺ΋+BWBྺ΋೥໨ w +BWBͱ4QSJOHͰz(*3-4Λ)"11:ʹz͢Δ࢓ࣄΛ͍ͯ͠·͢ w େֶ࣌୅͸1ZUIPOͰ8FCΞϓϦΛ։ൃ ޷͖ͳ΋ͷ ษڧձͷελοϑɺϊϕϧςΟͷൃ஫ɺ͓͍͍͓͠ञ 
ϔΞΧϥʔϒϦʔνɺ୐഑ͷ഑ૹঢ়گΛோΊΔ ླ໦ਅੜ !NBTBP[J !2 ʘ·͓͞Ͱ͢ʗ w w w

w ࠓ೔ͷΰʔϧ w ࿩ͷ͖͔͚ͬ w ฐࣾͷαʔϏεͱٕज़બ୒ͷ࿩ w ೔ʑͷӡ༻͔ΒΈΔ+BWBͰ͋Δཧ༝ w ʲ͓·͚ʳ+%,ͷҠߦͷ࿩
w ݁࿦ w ͓͠Βͤ ࠓ೔࿩͢͜ͱ !3 ੩͔ʙʹฉ͘ΑΓ΋  ΘʔΘʔݴ͍ͳ͕Β  ฉ͍ͯ΋Β͑Ε͹خ͍͠Ͱ͢ʂ

w ࠓ೔ͷΰʔϧ w ࿩ͷ͖͔͚ͬ w ฐࣾͷαʔϏεͱٕज़બ୒ͷ࿩ w ೔ʑͷӡ༻͔ΒΈΔ+BWBͰ͋Δཧ༝ w ʲ͓·͚ʳ+%,ͷҠߦͷ࿩
w ݁࿦ w ͓͠Βͤ ࠓ೔࿩͢͜ͱ !4 ʮ೥ӡ༻ͯ͠ʯͱ͍͍ͭͭ  ೥ϲ݄͔͠ݟͯͳ͍ͷͰ  ௐ΂ͨ৘ใ΋͋Γ·͢

ࠓ೔ͷΰʔϧ

!6 ʮ+BWB͕దͨ͠αʔϏεͱ͸Կ͔ʯ ΁ͷҰͭͷղΛݟ͚ͭΔ͜ͱ

࿩ͷ͖͔͚ͬ

w 4DBMB͕େ޷͖ͳઌഐ͕+BWBΛॻ͍͍ͯͯ೔ʑۤͦ͠͏Ͱ͋Δ w पғͷ༑ਓ͕ʮ+BWB͸ઈରॻ͖ͨ͘ͳ͍ʯͳͲݴ͍ͬͯͯɺ  ͳΜ͔ͩ൵͍͠ w ͱ͸͍͑ࣗ෼΋+BWB͕͘͢͝޷͖ͱ͍͏Θ͚Ͱ͸ͳ͍ w ྡͷνʔϜ͸αʔόʔαΠυ,PUMJOΛݕ౼͍ͯ͠ΔΑ͏ͩʁ w
ผͷݴޠΛݕ౼ͨ͜͠ͱ͸͋ΔΒ͍͠ɹɹɹɹɹͳͲͳͲ ࿩ͷ͖͔͚ͬ !8

w 4DBMB͕େ޷͖ͳઌഐ͕೔ʑۤͦ͠͏Ͱ͋Δ w पғͷ༑ਓ͕ʮ+BWB͸ઈରॻ͖ͨ͘ͳ͍ʯͳͲݴ͍ͬͯͯɺͳΜ͔ͩ൵ ͍͠ w ͱ͸͍͑ࣗ෼΋+BWB͕͘͢͝޷͖ͱ͍͏Θ͚Ͱ͸ͳ͍ w ྡͷνʔϜ͸αʔόαΠυ,PUMJOΛݕ౼͍ͯ͠ΔΑ͏ͩʁ w
ผͷݴޠΛݕ౼ͨ͜͠ͱ͸͋ΔΒ͍͠ ࿩ͷ͖͔͚ͬ !9 ͳΜͰ+BWBΛ࢖͍ͬͯΔΜͩΖ͏ʁ +BWB͕ద͍ͯ͠Δ΋ͷͬͯͳΜͩΖ͏ʁ ഑ଐ͞ΕͨϓϩμΫτ͕+BWB͔ͩͬͨΒ  Ҏ֎ͷཧ༝͸ͳ͍ͷͩΖ͏͔ʁ

w 4DBMB͕େ޷͖ͳઌഐ͕೔ʑۤͦ͠͏Ͱ͋Δ w पғͷ༑ਓ͕ʮ+BWB͸ઈରॻ͖ͨ͘ͳ͍ʯͳͲݴ͍ͬͯͯɺͳΜ͔ͩ൵ ͍͠ w ͱ͸͍͑ࣗ෼΋+BWB͕͘͢͝޷͖ͱ͍͏Θ͚Ͱ͸ͳ͍ w ྡͷνʔϜ͸αʔόαΠυ,PUMJOΛݕ౼͍ͯ͠ΔΑ͏ͩʁ w
ผͷݴޠΛݕ౼ͨ͜͠ͱ͸͋ΔΒ͍͠ ࿩ͷ͖͔͚ͬ !10 ⾠ܾͯ͠ϚαΧϦΛ౤͛ʹདྷͨͷͰ͸ͳ͍Ͱ͢ ʮ࢖͏͔Βʹ͸ɺྑ͞Λ஌Γ͍ͨʯ Έͳ͞Μͷ+BWBΛબΜͩཧ༝΍  +BWBͷ޷͖ͳͱ͜ΖͳͲ΋ͥͻฉ͖͍ͨͰ͢

ฐࣾͷαʔϏεͱ  ٕज़બ୒ͷ࿩

w ϓϦըऔಘαʔϏε  ϓϦϯτγʔϧػͰࡱӨͨ͠ը૾Λ  εϚϗ΍Ψϥέʔʹμ΢ϯϩʔυ͢Δ w ϓϦըΛ࢖ͬͨ4/4 w Խহ඼ͷϓϨθϯτ w ϓϦᝑମͷޱίϛ
ฐࣾͷαʔϏεϐΫτϦϯΫ !12

w தֶੜʙେֶੜͷ(*3-4͕λʔήοτ  ˞(*3-4ʜࣗ෼Λ(*3-4ͱೝ͍ࣝͯ͠Δ͢΂ͯͷਓ w ձһ਺ສਓҎ্ w ଔۀࣜɺϋϩ΢ΟϯɺΫϦεϚεͳͲʹ  ΞΫηε͕૿͑Δ ฐࣾͷαʔϏεϐΫτϦϯΫ
!13

w ೥Ψϥέʔ޲͚αΠτΛϦϦʔε  αʔόʔͷ࣮૷͸+BWB w ೥εϚϗ޲͚αΠτωΠςΟϒΞϓϦΛϦϦʔε  αΠτΞϓϦͷαʔόʔ͸ͱ΋ʹ+BWB  "OESPJEΞϓϦ΋+BWB w ೥ݱࡏʜ  ਓͰӡ༻։ൃத
ฐࣾͷαʔϏεϐΫτϦϯΫ !14

w ೥Ψϥέʔ޲͚αΠτΛϦϦʔε  αʔόʔͷ࣮૷͸+BWB w ೥εϚϗ޲͚αΠτωΠςΟϒΞϓϦΛϦϦʔε  αΠτΞϓϦͷαʔόʔ͸ͱ΋ʹ+BWB  "OESPJEΞϓϦ΋+BWB w ೥ݱࡏʜ  ਓͰӡ༻։ൃத
ฐࣾͷαʔϏεϐΫτϦϯΫ !15   ࠓ΋มΘΒͣ+BWB+BWB͍ͯ͠Δʂ

ٕज़બ୒ͷ࿩+BWB !16 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ ஌ݟ͕ઌબ୒ࢶͷগͳ͞

w ʙ೥ࠒ+BWB͕ग़࢝Ίͨ࣌୅  ιϑτ΢ΣΞ։ൃݚڀͷΑ͏ͳͱ͜Ζ  +BWBͰԿ͔ࣄۀ͕Ͱ͖ͳ͍͔ͱ໛ࡧ ٕज़બ୒ͷ࿩ !17 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ +BWBͰ  Կ͔ʜ

ٕज़બ୒ͷ࿩ !18 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ w ʙ೥ࠒ+BWB͕ग़࢝Ίͨ࣌୅  +BWBͰԿ͔ࣄۀ͕Ͱ͖ͳ͍͔ͱ໛ࡧ w ௨৴ܥϛυϧ΢ΣΞ͕׬੒

ٕज़બ୒ͷ࿩ !19 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ Τϯλϝ  ͍ͨ͠ͳ w ΤϯλʔςΠϯϝϯτܥͷ͜ͱ΋͍ͨ͠ʂ  ϓϦػͱΨϥέʔͷ௨৴ͱ͔Ͳ͏ͩΖ͏͔

ٕज़બ୒ͷ࿩ !20 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ w ΤϯλʔςΠϯϝϯτܥͷ͜ͱ΋͍ͨ͠ʂ w ଞͷݴޠ΋ݕ౼ͯ͠Έͨˠબ୒ࢶ͕গͳ͍ w "QBDIF5PNDBUͰͭ͘ΔΑ͏ͳ΋ͷ 1FSM
"QBDIF "QBDIF  5PNDBU +BWB

ٕज़બ୒ͷ࿩ !21 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ w ΤϯλʔςΠϯϝϯτܥͷ͜ͱ΋͍ͨ͠ʂ w ଞͷݴޠ΋ݕ౼ͯ͠Έͨˠબ୒ࢶ͕গͳ͍ w "QBDIF5PNDBUͰͭ͘ΔΑ͏ͳ΋ͷ w
ࣾ಺ʹ+BWBͷ஌ݟ͕ཷ·͍ͬͯΔͳʜ 1FSM "QBDIF "QBDIF  5PNDBU +BWB

ٕज़બ୒ͷ࿩ !22 Ψϥέʔ޲͚αʔϏε͕+BWBͰ͋ͬͨཧ༝ w ΤϯλʔςΠϯϝϯτܥͷ͜ͱ΋͍ͨ͠ʂ w ଞͷݴޠ΋ݕ౼ͯ͠Έͨˠબ୒ࢶ͕গͳ͍ w "QBDIF5PNDBUͰͭ͘ΔΑ͏ͳ΋ͷ w
ࣾ಺ʹ+BWBͷ஌ݟ͕ཷ·͍ͬͯΔͳʜ +BWB ஌ݟ͕ઌબ୒ࢶͷগͳ͞Ͱ+BWBʹ

ٕज़બ୒ͷ࿩ !23 ҆ఆͱલ਎αʔϏεɺ+7. εϚϗ޲͚αʔϏε͕+BWBʹͳͬͨཧ༝

w ʙ೥ͷϦϦʔεʹ޲͚ٕͯज़ݕ౼Λ͢Δ  +BWBʹݶΒͣଞͷݴޠ΍ϑϨʔϜϫʔΫ΋ݕ౼ w ֶशίετ͕Ͳͷ͘Β͍ͳͷ͔ w ϑϨʔϜϫʔΫͷ҆ఆ౓߹͍ɹɹͳͲͳͲ ٕज़બ୒ͷ࿩ !24 εϚϗ޲͚αʔϏε͕+BWBʹͳͬͨཧ༝
4 1MBZ +BWB ʜ 1)1 4DBMB

w ʙ೥ͷϦϦʔεʹ޲͚ٕͯज़ݕ౼Λ͢Δ  +BWBʹݶΒͣଞͷݴޠ΍ϑϨʔϜϫʔΫ΋ݕ౼ w ࣾ಺ࢿ࢈͸׆༻͍ͨ͠ͷͰ+7.ݴޠ͕ྑ͍  Ψϥέʔ޲͚αʔϏεͰ։ൃͨ͠ϥΠϒϥϦͳͲ ٕज़બ୒ͷ࿩ !25 εϚϗ޲͚αʔϏε͕+BWBʹͳͬͨཧ༝ 4
1MBZ +BWB ʜ 1)1 4DBMB

w ʙ೥ͷϦϦʔεʹ޲͚ٕͯज़ݕ౼Λ͢Δ  +BWBʹݶΒͣଞͷݴޠ΍ϑϨʔϜϫʔΫ΋ݕ౼ w ࣾ಺ࢿ࢈͸׆༻͍ͨ͠ͷͰ+7.ݴޠ͕ྑ͍  Ψϥέʔ޲͚αʔϏεͰ։ൃͨ͠ϥΠϒϥϦͳͲ w 1MBZͱ4DBMBͷ૊Έ߹Θ͕ͤ҆ఆ͍ͯ͠ͳ͍࣌ظ ٕज़બ୒ͷ࿩ !26
εϚϗ޲͚αʔϏε͕+BWBʹͳͬͨཧ༝ 4 1MBZ +BWB ʜ 1)1 4DBMB

w ʙ೥ͷϦϦʔεʹ޲͚ٕͯज़ݕ౼Λ͢Δ  +BWBʹݶΒͣଞͷݴޠ΍ϑϨʔϜϫʔΫ΋ݕ౼ w ࣾ಺ࢿ࢈͸׆༻͍ͨ͠ͷͰ+7.ݴޠ͕ྑ͍  Ψϥέʔ޲͚αʔϏεͰ։ൃͨ͠ϥΠϒϥϦͳͲ w 1MBZͱ4DBMBͷ૊Έ߹Θ͕ͤ҆ఆ͍ͯ͠ͳ͍࣌ظ ٕज़બ୒ͷ࿩ !27
εϚϗ޲͚αʔϏε͕+BWBʹͳͬͨཧ༝ 4 1MBZ +BWB ʜ 1)1 4DBMB ҆ఆͱલ਎αʔϏεɺ+7.Ͱ+BWBʹ

w ೥Ψϥέʔ޲͚αΠτΛϦϦʔε  ஌ݟ͕ઌબ୒ࢶͷগͳ͔͞Β+BWBʹ w ೥εϚϗ޲͚αΠτωΠςΟϒΞϓϦΛϦϦʔε  ҆ఆͱલ਎αʔϏεɺ+7.͔Β+BWBʹ ٕज़બ୒ͷ࿩·ͱΊ !28 ݴޠ࢓༷Ͱ͸ͳ͍෦෼͕ओͳཧ༝

೔ʑͷӡ༻͔ΒΈΔ  +BWBͰ͋Δཧ༝

!30 ݴޠͷϢʔβʔ͕ଟ͍ ੩తܕ෇͚ίϯύΠϥ͕ڧྗͰ͋Δ ྫ֎Λ໌֬ʹॲཧͰ͖Δ

Ϣʔβʔ਺ͷগͳ͍ݴޠ΍ϑϨʔϜϫʔΫΛ࢖͍ͬͯͨࠒ w ࣅͨ͜ͱΛ͍ͯ͠Δਓ͕ډͳ͍ w ຊ΋هࣄ΋͋Μ·Γͳ͍ ࠔ͔ͬͯΒղܾ·Ͱ͕ԕ͔ͬͨ ݴޠͷϢʔβʔ͕ଟ͍ !32 ͍ͬͺ͍ͭΒ͍

Ͱ΋+BWBͳΒ w ࣅͨ͜ͱΛ͍ͯ͠Δਓ͕୔ࢁډΔ w ຊ΋هࣄ΋୔ࢁ͋Δ ࠔͬͯ΋ௐ΂Ε͹ॿ͔Δ཰͕ߴ͍ ٯʹ৘ใʹຒ΋Εͯ͠·͏͜ͱ΋͋Δ ݴޠͷϢʔβʔ͕ଟ͍ !33 ͭΒ͘ͳ͍ʂ

ϝϯςφϯε͞Ε͍ͯΔ΋ͷ͕ଟ͘ɺ࢖͍ଓ͚ΒΕΔ҆৺͕͋Δ w ϥΠϒϥϦɺϑϨʔϜϫʔΫͳͲ w ࢖͏ਓ͕ډΔ͠ɺίϛοτ͢Δਓ͕͍Δ େن໛ͳαʔϏεͱͯ͠͸҆৺ͯ͠࢖͑Δ͜ͱ͕خ͍͠ ⾠ར༻͢Δ͚ͩͰͳ͘ίϛοτ͍͖ͯ͠·͠ΐ͏ͱ͍͏࿩ ݴޠͷϢʔβʔ͕ଟ͍ !34

ࣾ಺֎໰ΘͣਓతϦιʔε͕५୔Ͱ͋Δ w ଞ෦ॺͱਓΛߦ͖དྷͰ͖Δ w શ͘ҟͳΔ੡඼Λ࡞Δ෦ॺͱٕज़ަྲྀ͕Ͱ͖Δ  ᝒମͷ૊ΈࠐΈιϑτ΢ΣΞͷνʔϜͳͲ w ࣾ֎Ͱ΋ਓΛݟ͚ͭ΍͍͢ w ++6($$$ͱ͔΋ָ͍͋ͬͯ͠☺ 
ݴޠͷϢʔβʔ͕ଟ͍ !35

+BWB͸੩తܕ෇͚ݴޠ  ɹɹɹίϯύΠϧ࣌ʹܕνΣοΫΛͯ͘͠ΕΔ ྫ͑͹ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !37

ϥΠϒϥϦଆͰ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !38   public interface VegetableService { /** *
ݱࡏͷ०ͷ໺ࡊΛฦ͢ * @return */ Vegetable getInSeason(List<Vegetable> vegetables); }

ར༻ଆͰ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !39   public class KithenController { @Resource VegetableService
vegetableService; @RequestMapping(path = "/recommend") public ModelAndView recommendMenu() { List<Vegetable> vegetables = refrigeratorService.findVegetables(); Vegetable vegetable = vegetableService.getInSeason(vegetables); //ฦ͖ͬͯͨ໺ࡊͰ͓͢͢ΊͷݙཱΛߟ͑Δ… return new ModelAndView("/reccomend.html"); } }

vegetableService; @RequestMapping(path = "/recommend") public ModelAndView recommendMenu() { List<Vegetable> vegetables = refrigeratorService.findVegetables(); Vegetable vegetable = vegetableService.getInSeason(vegetables); //ฦ͖ͬͯͨ໺ࡊͰ͓͢͢ΊͷݙཱΛߟ͑Δ… return new ModelAndView("/reccomend.html"); } } ०ͷ໺ࡊͬͯ  Ұݸ͡Όͳ͍Αͳ

ݱࡏͷ०ͷ໺ࡊΛฦ͢ * @return */ List<Vegetable> getInSeason(List<Vegetable> vegetables); }

vegetableService; @RequestMapping(path = "/recommend") public ModelAndView recommendMenu() { List<Vegetable> stockVegetables = refrigeratorService.findVegetables(); List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables); //ฦ͖ͬͯͨ໺ࡊͰ͓͢͢ΊͷݙཱΛߟ͑Δ… return new ModelAndView("/reccomend.html"); } }

vegetableService; @RequestMapping(path = "/recommend") public ModelAndView recommendMenu() { List<Vegetable> stockVegetables = refrigeratorService.findVegetables(); List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables); //ฦ͖ͬͯͨ໺ࡊͰ͓͢͢ΊͷݙཱΛߟ͑Δ… return new ModelAndView("/reccomend.html"); } } ίϯύΠϧ  Τϥʔ

ಉ͘͡ར༻ଆͰ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !44 public class ShoppingController { @Resource VegetableService vegetableService;
@RequestMapping(path = "/market") public ModelAndView market() { List<Vegetable> vegetables = specialPriceService.findVegetables(); Vegetable vegetable = vegetableService.getInSeason(vegetables); //ฦ͖ͬͯͨ०ͷ໺ࡊΛͲ΍͜΍… return new ModelAndView("/market.html"); } } ͸Θʔ͍͢·ͤΜ  ͦͬͪ΋࢖ͬͯͨ

ʮ͍΍͍΍ͦΕ͸ͳ͍ʯʮͦΜͳ͠ΐͬͺ͍ϛεʜʯ  ʮͦ΋ͦ΋ͦΜͳमਖ਼ͷ࢓ํʜʯ  ͱࢥ͍·͕͢ w ٸ͍Ͱमਖ਼͍ͯ͠Δͱ͖ w σʔλΞΫηε૚ʙϓϨθϯςʔγϣϯ૚·ͰҰؾʹ͔͍͍ͯΔͱ͖ w ϥΠϒϥϦ΋·ͱΊͯॻ͍ͯΔͱ͖ ͳͲɺҊ֎΍ͬͯ͠·͏ɻ
੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !45

ʜઌఔͷίʔυΛϦϦʔε͔ͯ͠Βϲ݄ޙʜ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !46

ݱࡏͷ०ͷ໺ࡊΛฦ͢ * @return */ List<Vegetable> getInSeason(List<Vegetable> vegetables); }

ݱࡏͷ०ͷ໺ࡊΛฦ͢ * @return */ List<Vegetable> getInSeason(List<Vegetable> vegetables) throws NoVegetablesException; } ۭͳΒ  ྫ֎ʹͨ͘͠  ͳ͖ͬͯͨ

ར༻ଆͰ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !49   List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables);   try
{ List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables); } catch (NoVegetablesException e) { e.printStackTrace(); } ,JUDIFO$POUSPMMFSͱ 4IPQQJOH$POUSPMMFSͰ  ࢖͚ͬͯͨͬͳʙ

ར༻ଆͰ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !50   List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables);   try
{ List<Vegetable> vegetables = vegetableService.getInSeason(stockVegetables); } catch (NoVegetablesException e) { e.printStackTrace(); } ίϯύΠϧ  Τϥʔ

ػೳ௥Ճ͞Ε͍ͯͨʂ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !51 public class FlyerController { @Resource VegetableService vegetableService;
@RequestMapping(path = "/available") public ModelAndView availableFlyerView() { List<Vegetable> vegetables = specialPriceService.findVegetables(); Vegetable vegetable = vegetableService.getInSeason(vegetables); //ฦ͖ͬͯͨ०ͷ໺ࡊΛͲ΍͜΍… return new ModelAndView(“/available.html"); } } Θʔ͓  ͦͬͪ΋࢖ͬͯͨ

ͪ͜Β΋ʮͦΜͳ͜ͱ͋Δʁʯͱࢥ͏͔΋͠Ε·ͤΜ͕ w େ͖ͳ࣮૷ ϲ݄Ҏ্͔͔ΔͳͲ Λ͍ͯ͠Δͱ͖ w ಉ͡ϓϩμΫτʹରͯͦ͠Μͳ࣮૷͕ฒߦͰ૸Δঢ়گͷͱ͖ ͳͲ΍͸Γ΍ͬͯ͠·͏৔໘͕͋Δɻ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !52

੩తܕ෇͚ͰίϯύΠϥ͕ڧྗ !53 ࡉ͔͍ϛε͸ಈ͔͢લʹؾ͚ͮΔ΄͏͕  Ұͭͣͭண࣮ʹ࣮૷ΛਐΊΒΕΔͷͰ  ॻ͖͸͡Ί͔Β׬ྃ·Ͱ͕ૣ͍ ͱ͸͍͑*%&͕ݡ͘ར༻ՕॴΛ୳ͤͨΓ͢ΔͷͰ  ίϯύΠϥΛ௨ͣ͞ͱ΋ؾ͚ͮΔͱ΋͍͏

Ϣʔβʔ͕ສਓ͍Δͱʮكͳҟৗܥʯׂ͕ͱΑ͘ൃੜ͢Δ ྫ֎Λ໌֬ʹॲཧͰ͖Δ !55 //΄΅ى͜Γ͑ͳ͍͕… if(hoge.isEmpty()) { return new Collections.emptyList(); }

Ϣʔβʔ͕ສਓ͍Δͱʮكͳҟৗܥʯׂ͕ͱΑ͘ൃੜ͢Δ w ࣮૷࣌఺Ͱ͸ຊ౰ʹك͕ͩͬͨଞͷػೳ௥ՃͰى͖΍͘͢ͳͬͨ w ϦϦʔε͔ͯ͠Β݁ߏك͡Όͳ͍ͳͱൃ֮ɹͳͲͳͲ ྫ֎Λ໌֬ʹॲཧͰ͖Δ !56

Ϣʔβʔ͕ສਓ͍Δͱʮكͳҟৗܥʯׂ͕ͱΑ͘ൃੜ͢Δ ྫ֎Λ໌֬ʹॲཧͰ͖Δ !57 //΄΅ى͜Γ͑ͳ͍͕… if(hoge.isEmpty()) { return new Collections.emptyList(); }
ى͜ΔΜ͔ʜ

Ϣʔβʔ͕ສਓ͍Δͱʮكͳҟৗܥʯׂ͕ͱΑ͘ൃੜ͢Δ   ͜͏͍͏ಛघέʔεʹରͯ͠ɺ  ࣗ෼͕ͨͪѻ͍΍͍͢ྫ֎Λఆٛͯ͠ॲཧΛଅͤΔͷ͸ར఺ ྫ֎Λ໌֬ʹॲཧͰ͖Δ !58 //΄΅ى͜Γ͑ͳ͍͕… if(hoge.isEmpty()) { return
throw new HogeIsEmptyException(); } ྫ֎ʹͨͬͨ͠ ΄͏͕͍ͳ

!60 ݴޠͷϢʔβʔ͕ଟ͍ ੩తܕ෇͚ίϯύΠϥ͕ڧྗͰ͋Δ ྫ֎Λ໌֬ʹॲཧͰ͖Δ Ћ

ศརͳ΋ͷ͕୔ࢁ͋Γɺ։ൃεϐʔυ͕ૣ͍ w *%&͕ڧྗ  ϦϑΝΫλϦϯάҰͭͰ΋ݡ͍ػೳ͕උΘ͍ͬͯΔ΋ͷ͕͋Δ  ิ׬͕ڧྗɺ$POWFSU5P,PUMJOͱ͔·Ͱ͋Δ  ॻ͘εϐʔυ͕ૣ͘ͳΔ w ඪ४ϥΠϒϥϦ͕ॆ࣮͍ͯ͠Δ  ϥΠϒϥϦΛ୳͕࣌ؒ͢ݮΔͷͰ࣮૷ʹूதͰ͖Δ ʲ
Ћʳ  ։ൃ؀ڥ͕ڧྗͳ࿩ !61

ศརͳ΋ͷ͕୔ࢁ͋Γɺ։ൃεϐʔυ͕ૣ͍ ॳ৺ऀͰ΋ʮ·ͣಈ͘΋ͷʯ͕ग़དྷ্͕Δ·Ͱ͕ૣ͍ w ࠔͬͨˠͰָ͖͍͕ͨ͠ૣ͍ w ࣗ৴ͱ͔Ϟνϕʔγϣϯʹ௚݁͢Δ ʲ Ћʳ ։ൃ؀ڥ͕ڧྗͳ࿩ !62

ʲ͓·͚ʳ  +%,ͷҠߦͷ࿩

w ϐΫτϦϯΫͰ͸0SBDMF+%,Λ࢖͍ͬͯͨ +%,ͷҠߦ !64 0SBDMF +%,ʙ̇

w ϐΫτϦϯΫͰ͸0SBDMF+%,Λ࢖͍ͬͯͨ w 0SBDMFͷαϙʔτϙϦγʔ͕มΘͬͨ  ࣮ӡ༻Ͱ࢖͑Δ+%,͸೥݄·Ͱ  Ҿ͖ଓ͖࢖͏ʹ͸ܖ໿͕ඞཁ  ͦΕ΋೥ؒͰαϙʔτऴྃͷ༧ఆ  +%,Ҏ߱΋ಉ͘͡ܖ໿͕ඞཁ w Կ͔͠ΒରԠΛ͠ͳͯ͘͸ͳΒͳ͍ঢ়گ
+%,ͷҠߦ !65 αϙʔτ ऴΘΔΑʂ

ߟ͑ΒΕΔબ୒ࢶ͸͍͔ͭ͘ w 0SBDMF+%,Ͱܖ໿͢Δ w 0SBDMF+%,Ͱܖ໿͢Δ w ֤ࣾஂମͷ+%,ʹҠߦ͢Δ w ͍ͬͦଞͷݴޠʹͯ͠͠·͏ +%,ͷҠߦ
!66

ߟ͑ΒΕΔબ୒ࢶ͸͍͔ͭ͘ w 0SBDMF+%,Ͱܖ໿͢Δ w 0SBDMF+%,Ͱܖ໿͢Δ w ֤ࣾஂମͷ+%,ʹҠߦ͢Δ w ͍ͬͦଞͷݴޠʹͯ͠͠·͏ +%,ͷҠߦ
!67 ͙͢ʹରԠ͢Δͷ͸೉͍͠ ͙͢ʹରԠ͢Δͷ͸೉͍͠ ͳ͔ͳ͔ͷֹۚʹͳΓͦ͏ʜ ͳ͔ͳ͔ͷֹۚʹͳΓͦ͏ʜ

w ͻͱ·ͣ"EPQU0QFO+%,ʹҠߦ͢Δ͜ͱʹ w खॱʹಛผͳ͜ͱ͸ͳ͍ w ΞϓϦέʔγϣϯ͔Β"EPQU0QFO+%,Λࢀর͢ΔΑ͏ʹ͢Δ w ςετ؀ڥͰϏϧυɺϢχοτςετ͕௨Δ͔νΣοΫ w ϲ݄΄Ͳςεταʔόʔʹஔ͍ͯΞϓϦέʔγϣϯΛ৮Γ͓ͨ͢
w όά౳Έ͋ͨΒͳ͚Ε͹ϦϦʔε +%,ͷҠߦ !68 ࠓίί

ࠓޙ w վΊͯͲͷ+%,ʹ͢Δͷ͔ w +BWBͷόʔδϣϯ΋Ͳ͏͢Δͷ͔ ͳͲΛݕ౼ͯ͠௥ͬͯରԠΛ͍ͯ͘͠༧ఆ +%,ͷҠߦ !69

ͱɺ͞Βͬͱ࿩͕͓ΘΓ·͕ͨ͠ +%,ͷҠߦ !70

w ରԠ͢ΔதͰɺ+BWBࣗମʹର͢ΔࠔΓ͝ͱ͸ಛʹແ͔ͬͨ w ਓͰ೰·ͳͯ͘΋ɺੈքதͷਓͷҙݟ͕ಘΒΕΔ w 0SBDMFҎ֎ʹ΋+%,ͷఏڙऀ͕͍Δ w ݟ͔ͭͬͨ՝୊͸ࣾ಺ͷ໰୊͹͔Γ w ৽͍͠όʔδϣϯʹ͙͢ʹରԠͰ͖ͳ͍ঢ়گΞʔΩςΫνϟ
+%,ͷҠߦ !71

ྺ࢙తܦҢ  ࣾ಺ʹઌʹ஌ݟ͕͋ͬͨɺଞͷબ୒ࢶͷͳ͞ ݴޠͷϢʔβʔ͕ଟ͍ ੩తܕ෇͚ͰίϯύΠϥ͕ڧྗͰ͋Δ ྫ֎Λ໌֬ʹॲཧͰ͖Δ ϐΫτϦϯΫ͕+BWBͰ͋Δཧ༝
!73

!74 ʮ+BWB͕దͨ͠αʔϏεͱ͸Կ͔ʯ

!75 w Ϣʔβʔ਺͕ଟ͘ɺن໛͕େ͖͍αʔϏε w ίϛοτ͢Δϝϯόʔ͕มԽ͠΍͍͢ɺ  ͍ͭ୭͕Ͳ͜Λ৮Δ͔ಡΊͳ͍αʔϏε

!76 w Ϣʔβʔ਺͕ଟ͘ɺن໛͕େ͖͍αʔϏε w ίϛοτ͢Δϝϯόʔ͕มԽ͠΍͍͢ɺ  ͍ͭ୭͕Ͳ͜Λ৮Δ͔ಡΊͳ͍αʔϏε Έͳ͞Μͷ͝ҙݟ΋  ͥͻฉ͖͍ͨͰ͢ʂ

!77 ϐΫτϦϯΫ͸+BWBͰΑ͔ͬͨʁ

!78 :&4

w ୭͕Ͳ͜Λ͍ͭ৮Δ͔Θ͔Βͳ͍ঢ়ଶ  গͳ͘ͱ΋νʔϜ͸ίʔυΛ৮ΔڪΕ͕͋ΔϓϩμΫτ  ͪΐͪ͜ΐ͜ଞ෦໳͔Βਓ͕དྷͨΓνʔϜฤ੒͕มΘͬͨΓ͢Δ  ͳͷͰ w ੩తܕ෇͚Ͱ͋Δ͜ͱͰࣗ෼ͷ஌Βͳ͍ͱ͜Ζ΋ͳΔ΂҆͘શʹ͠΍͍͢ w ଞ෦ॺ΋+BWBྺͷ͋Δਓ͕ଟ͍ͷͰߦ͖དྷ͠΍͍͢ ϐΫτϦϯΫ͕+BWBͰ͋Δཧ༝
!79

w Ϣʔβ਺͕ສਓ͍ΔͰ͔͍αʔϏεͰ͋Δ  ίϯύΠϧஈ֊Ͱ͔ͬ͠ΓνΣοΫͨ͠΋ͷΛੈʹग़ͤΔͷ͸͍ͩ͡  ϥΠϒϥϦͳͲ΋ϝϯς͞ΕͯΔ΋ͷ͕͔ͭ͑Δͷ͸خ͍͠  ҆શͳαʔϏεΛఏڙ͠΍͍͢ w ίʔυͷϘϦϡʔϜɺաڈͷࢿ࢈΋͔ͳΓͰ͔͍  աڈͷࢿ࢈ͱ͍͏ҙຯͰ͸+7.ݴޠͰ͋Ε͹׆༻Ͱ͖Δ ϐΫτϦϯΫ͕+BWBͰ͋Δཧ༝ !80

͓͠Βͤ

͓஌Βͤͦͷ̍ !82 Ұॹʹಇ͘ϝϯόʔΛืूதͰ͢ɻ ΤϯδχΞืूதʂ

͓஌Βͤͦͷ̍ !83 w ژ౎Ӻɹెา෼ w ΧϯϑΝϨϯε͸ࣾඅͰʂ  ަ௨අ॓ധඅࢀՃඅ͓څྉग़·͢ w ࣾ಺Ͱͷษڧձ΋͍Ζ͍Ζ w
ৄ͘͠͸ͪ͜Β ΤϯδχΞืूதʂ

͓஌Βͤͦͷ !84 ژ౎%FW͔;͐ w ژ౎Ӻલʙ w ςʔϚ͸৭ʑ w ίʔώʔɺ࠙਌ձ෇͖ w
ৄ͘͠͸DPOOQBTTͰʂ ษڧձ΍ͬͯΔͷͰདྷ͍ͯͩ͘͞ʂ

͓஌Βͤͦͷ !85 ొஃऀ΋ืूதͰ͢ʂ $G1ग़͔ͨͬͨ͠3FKFDUͩͬͨ  ࣗ෼͕Έͨηογϣϯ·ͱΊ  ͳͲͳͲͳΜͰ΋͟͝Εʂ

ສϢʔβʔͷ8FCαʔϏεΛ  ೥ӡ༻ͯ͠ߟ͑Δɺ+BWBͰ͋Δཧ༝ ϑϦϡʔגࣜձࣾླ໦ਅੜ !NBTBP[Jʣ ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ʂ

1400万ユーザーのWebサービスを 15年運用して考える、 Javaである理由

1400万ユーザーのWebサービスを 15年運用して考える、 Javaである理由

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1400万ユーザーのWebサービスを 15年運用して考える、 Javaである理由

1400万ユーザーのWebサービスを 15年運用して考える、 Javaである理由