Lombokの紹介

Java開発においてとても便利なLombokを説明します。

Transcript

1. Lombokͷ঺հ 2017-07-20 ࣾ಺ษڧձ onozaty
2. Lombok? • Javaͷఆܕతͳίʔυ(ϘΠϥʔϓϨʔτίʔ υ)ͷهड़Λഉআͯ͘͠ΕΔϥΠϒϥϦ • ఆܕతͳίʔυͱ͸ԼهͷΑ͏ͳ΋ͷ • getter/setter • equals, hashCode • toString • ίϯετϥΫλɹͳͲ
3. Lombok? • ΞϊςʔγϣϯΛ෇༩͓ͯ͘͠ͱɺίϯύΠϧ ࣌ʹίʔυΛຒΊࠐΜͰ͘ΕΔ @Getter @Setter public class Customer { private int id; private String name; } public class Customer { private int id; private String name; public int getId() { return this.id; } public String getName() { return this.name; } public void setId(final int id) { this.id = id; } public void setName(final String name) { this.name = name; } }
4. Lombok? • IDEʹ΋ରԠ͍ͯͯ͠ɺIDE্Ͱ΋ຒΊࠐ·Ε ͨϝιου͕֬ೝͰ͖Δ
5. ಋೖํ๏ • ίϯύΠϧ࣌ͷΫϥεύεʹLombokΛؚΊͯ ͓͚ͩ͘(࣮ߦ࣌ʹ͸ෆཁ) • IDEͰ༗ޮʹ͢Δʹ͸ผ్ઃఆ͕ඞཁ • EclipseͩͱɺLombokͷjarΛ࣮ߦͯ͠ɺ EclipseͷΠϯετʔϧσΟϨΫτϦࢦఆ͢ Ε͹ઃఆͰ͖Δ(؆୯)
6. @Getter, @Setter • ϑΟʔϧυʹର͢Δgetter/setterΛੜ੒ • ϑΟʔϧυ·ͨ͸Ϋϥεʹରͯ͠ࢦఆ͢Δ(Ϋϥε ʹରͯ͠ߦ͏ͱશϑΟʔϧυʹࢦఆͨ͠ͷͱಉ͡) • ΞΫηεम০ࢠΛࢦఆ͢Δ͜ͱ΋Ͱ͖Δ(σϑΥϧ τ͸public) • finalͳϑΟʔϧυʹ͸setter͸ੜ੒͞Εͳ͍(ίϯ ύΠϧΤϥʔʹͳΔͷͰ౰ͨΓલ)
7. @Getter, @Setter public class GetterSetterExample { // ϑΟʔϧυʹରͯ͠ࢦఆ @Getter @Setter private int id; // ΞΫηεϨϕϧΛࢦఆ @Setter(AccessLevel.PROTECTED) private String name; } public class GetterSetterExample { private int id; private String name; public int getId() { return this.id; } public void setId(final int id) { this.id = id; } protected void setName(final String name) { this.name = name; } }
8. @ToString • Ϋϥε໊ʴϑΟʔϧυͷ৘ใΛग़ྗ͢Δ toStringϝιουΛੜ੒ • σϑΥϧτͩͱશͯͷϑΟʔϧυ͕ग़ྗ͞Ε Δ͕ɺର৅ͷϑΟʔϧυΛࢦఆ͢Δ͜ͱ΋Մ ೳ
9. @ToString @ToString public class ToStringExample { private int id; private String name; public String getName() { return name; } } // excludeͰআ֎͢ΔϑΟʔϧυΛࢦఆ @ToString(exclude = "name") class ToStringExample2 { private int id; private String name; } public class ToStringExample { private int id; private String name; public String getName() { return name; } @Override public String toString() { return "ToStringExample(id=" + this.id + ", name=" + this.getName() + ")"; } } class ToStringExample2 { private int id; private String name; @Override public String toString() { return "ToStringExample2(id=" + this.id + ")"; } }
10. @EqualsAndHashCode • equalsͱhashCodeϝιουΛੜ੒ • σϑΥϧτͩͱશͯͷϑΟʔϧυΛର৅ͱ͠ ͨൺֱͱͳΔ͕ɺର৅ͷϑΟʔϧυΛࢦఆ͢ Δ͜ͱ΋Մೳ • ϑΟʔϧυ͕௥Ճ͞Εͨ৔߹ʹ௚͠๨ΕΔͱ ͍͏͜ͱ͕ͳ͘ͳΔͷͰɺLombok࢖͏͜ͱͰ όάΛ๷͛Δ
11. @EqualsAndHashCode @EqualsAndHashCode public class EqualsAndHashCodeExample { private int id; private String name; } // ಛఆͷϑΟʔϧυΛআ֎͢Δ͜ͱ΋Ͱ͖Δ @EqualsAndHashCode(exclude = "age") class EqualsAndHashCodeExample2 { private int id; private String name; private int age; } public class EqualsAndHashCodeExample { private int id; private String name; @Override public boolean equals(final Object o) { … } @Override public int hashCode() { … } } public class EqualsAndHashCodeExample2 { private int id; private String name; private int age; // age͸࢖༻͞Εͳ͍ @Override public boolean equals(final Object o) { … } @Override public int hashCode() { … } }
12. @AllArgsConstructor, @NoArgsConstructor, @RequiredArgsConstructor • ֤छίϯετϥΫλΛ࡞੒ • @AllArgsConstructorͰશͯͷϑΟʔϧυΛҾ਺ ͱͨ͠ίϯετϥΫλ • @NoArgsConstructorͰҾ਺ͳ͠ίϯετϥΫλ • @RequiredArgsConstructorͩͱɺfinal͕෇͍ͯ ͍ΔҾ਺ͷΈͷίϯετϥΫλ(final͕͍͍ͭͯΔ ͷ͕ͳ͚Ε͹ɺҾ਺ͳ͠ίϯετϥΫλʹͳΔ)
13. @AllArgsConstructor, @NoArgsConstructor, @RequiredArgsConstructor @AllArgsConstructor @NoArgsConstructor public class ConstructorExample { private int id; private String name; } @RequiredArgsConstructor class ConstructorExample2 { private final int id; private String name; } public class ConstructorExample { private int id; private String name; public ConstructorExample( final int id, final String name) { this.id = id; this.name = name; } public ConstructorExample() { } } class ConstructorExample2 { private final int id; private String name; public ConstructorExample2(final int id) { this.id = id; } }
14. @Data • ԼهͷΞϊςʔγϣϯΛશͯࢦఆͨ͠ͷͱಉ͡ • @ToString • @EqualsAndHashCode • @Getter • @Setter • @RequiredArgsConstructor • γϯϓϧͳσʔλΫϥεʹର͢Δఆܕతͳ΋ ͷΛ·ͱΊͯੜ੒͢Δ͜ͱ͕Ͱ͖Δ
15. @Data @Data public class DataExample { private final int id; private String name; } public class DataExample { private final int id; private String name; public DataExample(final int id) { this.id = id; } public int getId() { return this.id; } public String getName() { return this.name; } public void setName(final String name) { this.name = name; } @Override public boolean equals(final Object o) { … } @Override public int hashCode() { … } @Override public String toString() { … } }
16. @Value • ΫϥεɺϑΟʔϧυ͸finalʹͳͬͨ͏͑Ͱɺ ԼهΞϊςʔγϣϯͱಉ͡ • @ToString • @EqualsAndHashCode • @Getter • @RequiredArgsConstructor • ImmutableͳΫϥε
17. @Value @Value public class ValueExample { private int id; private String name; } public final class ValueExample { private final int id; private final String name; public ValueExample( final int id, final String name) { this.id = id; this.name = name; } public int getId() { return this.id; } public String getName() { return this.name; } @Override public boolean equals(final Object o) { … } @Override public int hashCode() { … } @Override public String toString() { … } }
18. @Builder • Builderύλʔϯ(GoFຊ͡Όͳͯ͘ɺEffective Javaʹࡌ͍ͬͯΔ΄͏ͷ)ͷBuilderΫϥεΛੜ ੒ • BuilderύλʔϯͰॻ͘ͱɺϑΟʔϧυ͕ଟ͍ Ϋϥεͷੜ੒͕Θ͔Γ΍͘͢ͳΔ
19. @Builder public static void main(String[] args) { // BuilderͰ͸ແ͍৔߹(ίϯετϥΫλͰ) Customer customer = new Customer( "Taro", "Yamada", "Tokyo", Arrays.asList("A", "B")); System.out.println(customer); } @AllArgsConstructor @ToString class Customer { private String firstName; private String lastName; private String city; private List<String> tags; } public static void main(String[] args) { // BuilderͰੜ੒ Customer customer = Customer.builder() .firstName("Taro") .lastName("Yamada") .city("Tokyo") .tag("A") .tag("B") .build(); System.out.println(customer); } @Builder @ToString class Customer { private String firstName; private String lastName; private String city; @Singular private List<String> tags; }
20. @Slf4j • logͱ͍͏staticͳLoggerΛຒΊࠐΜͰ͘ΕΔ • Slf4jҎ֎ʹ΋Apache commons log(@Log)ͳ Ͳʹ΋ରԠ͍ͯ͠Δ • Loggerੜ੒࣌ͷର৅Ϋϥε໊ؒҧ͕͑๷͛Δ ͷͰศར
21. @Slf4j @Slf4j public class LogExample { public static void main(String[] args) { log.info("main."); } } public class LogExample { private static final org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LogExample.class); public static void main(String[] args) { log.info("main."); } }
22. @NonNull • ࢦఆͨ͠ϑΟʔϧυ·ͨ͸Ҿ਺ʹର͢Δnull νΣοΫ͕௥Ճ͞ΕΔ(nullͷ৔߹ʹ NullPointerException͕౤͛ΒΕΔ) • Objects.requireNonNullͰॻ͘ΑΓख͕ؒল ͚Δ͔΋
23. @NonNull @RequiredArgsConstructor public class NonNullExample { @NonNull private String name; public void printLength( @NonNull String message) { System.out.println( message.length()); } } public class NonNullExample { @NonNull private String name; public void printLength( @NonNull String message) { if (message == null) { throw new NullPointerException("message"); } System.out.println(message.length()); } public NonNullExample( @NonNull final String name) { if (name == null) { throw new NullPointerException("name"); } this.name = name; } }
24. val • ୅ೖෆՄͳม਺એݴʴܕਪ࿦ • Scalaͷvalͱಉ͡Πϝʔδ
25. val public static void main(String[] args) { val list = new ArrayList<String>(); list.add("a"); list.add("b"); val item = list.get(0); System.out.println(item); } public static void main(String[] args) { final ArrayList<String> list = new ArrayList<String>(); list.add("a"); list.add("b"); final String item = list.get(0); System.out.println(item); }
26. @Cleanup • Ξϊςʔτͨ͠ϩʔΧϧม਺͕είʔϓ͔Βൈ ͚Δ࣌(࢖༻͞Εͳ͘ͳͬͨλΠϛϯά)ʹɺ closeϝιουΛݺͿίʔυ͕ੜ੒͞ΕΔ • try/finally ͰϦιʔεղ์͢ΔΑ͏ͳίʔυ • ݺͼग़͢ϝιου͸σϑΥϧτͩͱcloseϝ ιου͕ͩมߋ͢Δ͜ͱ΋Մೳ
27. @Cleanup public static void main(String[] args) throws IOException { Path filePath = Paths.get(args[0]); @Cleanup BufferedReader reader = Files.newBufferedReader(filePath); System.out.println(reader.readLine()); } public static void main(String[] args) throws IOException { Path filePath = Paths.get(args[0]); BufferedReader reader = Files.newBufferedReader(filePath); try { System.out.println(reader.readLine()); } finally { if (Collections.singletonList(reader).get(0) != null) { reader.close(); } } }
28. @Synchronized • ࢦఆͨ͠ϝιου಺ͰsynchronizedϒϩοΫ ͕ੜ੒͞ΕΔ • staticͳϝιουͱΠϯελϯεϝιουͦΕ ͧΕͰผͷLockΦϒδΣΫτ͕ੜ੒͞ΕΔ • ໌ࣔతʹLockΦϒδΣΫτΛࢦఆ͢Δ͜ͱ΋ Մೳ
29. @Synchronized public class SynchronizedExample { @Synchronized public static void hello() { System.out.println("hello"); } @Synchronized public void bye() { System.out.println("bye"); } } public class SynchronizedExample { private static final Object $LOCK = new Object[0]; private final Object $lock = new Object[0]; public static void hello() { synchronized (SynchronizedExample.$LOCK) { System.out.println("hello"); } } public void bye() { synchronized (this.$lock) { System.out.println("bye"); } } }
30. @SneakyThrows • ྫ֎ͷεϩʔ۟Λࢦఆ͠ͳͯ͘ࡁΉΑ͏ʹͳΔ(Ұ෦ͷྫ֎ ͷΈΛແࢹͱ͍͏ઃఆ΋Մೳ) • ඇνΣοΫྫ֎Ͱϥοϓ͢ΔΘ͚Ͱ͸ͳ͘ɺͦͷ··νΣο Ϋྫ֎͕εϩʔ͞ΕΔͷͰɺͼͬ͘Γͨ͠ • ݁ߏτϦοΩʔͳ࣮૷ʹͳ͍ͬͯͯ໘ന͍ͷͰɺڵຯ͕͋Δ ํ͸ԼهίʔυΛࢀর • https://github.com/rzwitserloot/lombok/blob/master/src/core/ lombok/Lombok.java#L49 • ͜ͷॲཧ͚ͩLombokଆͷϝιουݺͼग़͕͠ೖΔͷͰɺ࣮ ߦ࣌ʹ΋Lombokͷjar͕ඞཁͱͳͬͯ͠·͏
31. @SneakyThrows public class SneakyThrowsExample { @SneakyThrows public static void main(String[] args) { throw new Exception(); } } public class SneakyThrowsExample { public static void main(String[] args) { try { throw new Exception(); } catch (final Throwable $ex) { throw Lombok.sneakyThrow($ex); } } }
32. delombok • delombokΛ࢖͏ͱɺLombokͰੜ੒͞ΕΔ ίʔυͷΠϝʔδΛ֬ೝͰ͖Δ • ಈ࡞ʹٙ໰͕͋Δ৔߹ʹ͸ɺdelombokͰίʔ υͱͯ֬͠ೝ͢Δͱྑ͍ • https://projectlombok.org/features/delombok > java -jar lombok.jar delombok src -d src-delomboked
33. ੜ੒͞ΕͨϝιουʹΞϊςʔ γϣϯΛઃఆ͍ͨ͠ • LombokͰੜ੒͞Εͨϝιου΍ϝιουͷύ ϥϝʔλʹΞϊςʔγϣϯΛ෇༩͍ͨ͠৔߹ ʹ͸ɺonMethd΍onParamΛ࢖͏ • https://projectlombok.org/features/experimental/onX
34. LombokΛקΊΔཧ༝ • هड़͢ΔίʔυྔΛݮΒͤΔ • ίʔυͷهड़ϛεΛ๷͛Δ • ϑΟʔϧυ໊มΘͬͨͷʹɺgetter/setterͷ໊લม͑๨ ΕͨΓͱ͔ɺɺ • όά͕ೖΓࠐΈͮΒ͘ͳΔ • ϑΟʔϧυ͕૿͑ͨ࣌ʹɺequals΍hashCode΁ͷมߋ ͕࿙ΕͨΓͱ͔ɺɺ
35. LombokΛקΊΔཧ༝ • ಋೖ΋؆୯ͳͷͰੵۃతʹ࢖͍͍ͨ • ࣗ෼͸΋͏Lombokແ͠Ͱίʔυॻ͖ͨ͘ແ͍ • ͨͩ͠ɺͳΜͰ΋LombokͰॻ͔ͳ͚Ε͹͍͚ͳ ͍ͱ͍͏Θ͚Ͱ͸ͳ͘ɺLombokͰॻ͍ͨํ͕ྑ ͍ͱࢥ͏΋ͷΛ࢖͑͹ྑ͍ͱࢥ͏ • ݸਓతʹ͸ɺvalͱ@Cleanupɺ@SneakyThrows͸ࠓ· Ͱ࢖ͬͨ͜ͱ͕ͳ͘ɺࠓޙ΋࢖Θͳͦ͏(LombokͰॻ ͘·Ͱ΋ແ͍ؾ͕͢Δ)
36. ऴΘΓʹ • Φϓγϣϯతͳ΋ͷ͸શ෦͸આ໌Ͱ͖͍ͯͳ ͍ͷͰɺLombokͷެࣜαΠτ΋͋Θͤͯ֬͝ ೝΛ • https://projectlombok.org/features/all