简介 lombok是一个编译级别的插件，它可以在项目编译的时候生成一些代码。通俗的说，lombok可以通过注解来标示生成getter settter等代码。
引入 创建gradle项目
1 compile group: 'org.projectlombok', name: 'lombok', version: '1.16.20'
注解 @NonNull
标记字段不可为null
1 2 3 4 5 6 7 @Setter public class Person @NonNull private String name; @NonNull private Integer age; }
对应的字节码文件：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 public class Person @NonNull private String name; @NonNull private Integer age; public Person () } public void setName (@NonNull String name) if (name == null ) { throw new NullPointerException("name" ); } else { this .name = name; } } public void setAge (@NonNull Integer age) if (age == null ) { throw new NullPointerException("age" ); } else { this .age = age; } } }
@Getter/@Setter
自动生成getter和setter方法
1 2 3 4 5 6 public class Person @Getter private String name; @Setter private Integer age; }
对应的字节码文件：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 public class Person private String name; private Integer age; public Person () } public String getName () return this .name; } public void setAge (Integer age) this .age = age; } }
@Cleanup
自动关闭流代码
1 2 @Cleanup InputStream in = new FileInputStream(args[0 ]);
对应的字节码文件：
1 2 3 4 InputStream in = new FileInputStream(args[0 ]); if (Collections.singletonList(in).get(0 ) != null ) { in.close(); }
@AllArgsConstructor/@NoArgsConstructor/@RequiredArgsConstructor
自动生成全参构造函数和无参构造函数
1 2 3 4 5 6 @AllArgsConstructor @NoArgsConstructor public class Person private String name; private Integer age; }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 12 public class Person private String name; private Integer age; public Person (String name, Integer age) this .name = name; this .age = age; } public Person () } }
@Builder
自动生成建造者模式的bean
1 2 3 4 5 @Builder public class Person private String name; private Integer age; }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 public class Person private String name; private Integer age; Person(String name, Integer age) { this .name = name; this .age = age; } public static Person.PersonBuilder builder () { return new Person.PersonBuilder(); } public static class PersonBuilder private String name; private Integer age; PersonBuilder() { } public Person.PersonBuilder name (String name) { this .name = name; return this ; } public Person.PersonBuilder age (Integer age) { this .age = age; return this ; } public Person build () return new Person(this .name, this .age); } public String toString () return "Person.PersonBuilder(name=" + this .name + ", age=" + this .age + ")" ; } } }
@EqualsAndHashCode
自动生成equals和hashcode方法
1 2 3 4 5 @EqualsAndHashCode public class Person private String name; private Integer age; }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 public class Person { private String name; private Integer age; public Person() { } public boolean equals(Object o) { if (o == this) { return true; } else if (!(o instanceof Person)) { return false; } else { Person other = (Person)o; if (!other.canEqual(this)) { return false; } else { Object this$name = this.name; Object other$name = other.name; if (this$name == null) { if (other$name != null) { return false; } } else if (!this$name.equals(other$name)) { return false; } Object this$age = this.age; Object other$age = other.age; if (this$age == null) { if (other$age != null) { return false; } } else if (!this$age.equals(other$age)) { return false; } return true; } } } protected boolean canEqual(Object other) { return other instanceof Person; } public int hashCode() { int PRIME = true; int result = 1; Object $name = this.name; int result = result * 59 + ($name == null ? 43 : $name.hashCode()); Object $age = this.age; result = result * 59 + ($age == null ? 43 : $age.hashCode()); return result; } }
@ToString
自动生成toString()方法
1 2 3 4 5 @ToString public class Person private String name; private Integer age; }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 public class Person private String name; private Integer age; public Person () } public String toString () return "Person(name=" + this .name + ", age=" + this .age + ")" ; } }
@Value
自动生成全参构造函数、Getter方法、equals方法、hashCode法、toString方法
1 2 3 4 5 @Value public class Person private String name; private Integer age; }
注意：@Value不会生成Setter方法
@Synchronized
自动为被标记的方法添加synchronized锁
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 public class SynchronizedExample private final Object readLock = new Object(); @Synchronized public static void hello () System.out.println("world" ); } @Synchronized public int answerToLife () return 42 ; } @Synchronized("readLock") public void foo () System.out.println("bar" ); } }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 public class SynchronizedExample private static final Object $LOCK = new Object[0 ]; private final Object $lock = new Object[0 ]; private final Object readLock = new Object(); public static void hello () synchronized ($LOCK) { System.out.println("world" ); } } public int answerToLife () synchronized ($lock) { return 42 ; } } public void foo () synchronized (readLock) { System.out.println("bar" ); } } }
@Delegate
为标记属性生成委托方法
1 2 3 4 5 6 7 8 9 10 public class DelegateExample public void show () System.out.println("show..." ); } } @AllArgsConstructor public class Demo @Delegate private final DelegateExample delegateExample; }
对应的字节码文件
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 public class DelegateExample public DelegateExample () } public void show () System.out.println("show..." ); } } public class Demo private final DelegateExample delegateExample; public Demo (DelegateExample delegateExample) this .delegateExample = delegateExample; } public void show () this .delegateExample.show(); } }
