Lombok 使用小结
Lombok 简介
Lombok 是一种 Java 实用工具，可用来帮助开发人员消除 Java 的冗长，尤其是对于简单的 Java 对象（POJO）。它通过注释实现这一目的。通过在开发环境中实现 Lombok，开发人员可以节省构建诸如 hashCode() 和 equals() 、getter / setter 这样的方法以及以往用来分类各种 accessor 和 mutator 的大量时间。
Lombok 安装
使 IntelliJ IDEA 支持 Lombok 方式如下：
（1）Intellij 设置支持注解处理
点击 File > Settings > Build > Annotation Processors
勾选 Enable annotation processing
（2）安装插件
点击 Settings > Plugins > Browse repositories
查找 Lombok Plugin 并进行安装
重启 IntelliJ IDEA
（3）将 lombok 添加到 pom 文件
org.projectlombok lombok 1.16.8
Lombok 使用
API
Lombok 提供注解 API 来修饰指定的类：
@Getter and @Setter
Lombok 代码：
@Getter @Setter private boolean employed = true;@Setter(AccessLevel.PROTECTED) private String name;
等价于 Java 源码：
private boolean employed = true;private String name;public boolean isEmployed() { return employed;}public void setEmployed(final boolean employed) { this.employed = employed;}protected void setName(final String name) { this.name = name;} @NonNull
Lombok 代码：
@Getter @Setter @NonNullprivate Listmembers;
等价于 Java 源码：
@NonNullprivate Listmembers;public Family(@NonNull final List members) { if (members == null) throw new java.lang.NullPointerException("members"); this.members = members;}@NonNullpublic List getMembers() { return members;}public void setMembers(@NonNull final List members) { if (members == null) throw new java.lang.NullPointerException("members"); this.members = members;}
@ToString
Lombok 代码：
@ToString(callSuper=true,exclude="someExcludedField")public class Foo extends Bar { private boolean someBoolean = true; private String someStringField; private float someExcludedField;} 等价于 Java 源码：
public class Foo extends Bar { private boolean someBoolean = true; private String someStringField; private float someExcludedField; @java.lang.Override public java.lang.String toString() { return "Foo(super=" + super.toString() + ", someBoolean=" + someBoolean + ", someStringField=" + someStringField + ")"; }} @EqualsAndHashCode
Lombok 代码：
@EqualsAndHashCode(callSuper=true,exclude={"address","city","state","zip"})public class Person extends SentientBeing { enum Gender { Male, Female } @NonNull private String name; @NonNull private Gender gender; private String ssn; private String address; private String city; private String state; private String zip;} 等价于 Java 源码：
public class Person extends SentientBeing { enum Gender { /*public static final*/ Male /* = new Gender() */, /*public static final*/ Female /* = new Gender() */; } @NonNull private String name; @NonNull private Gender gender; private String ssn; private String address; private String city; private String state; private String zip; @java.lang.Override public boolean equals(final java.lang.Object o) { if (o == this) return true; if (o == null) return false; if (o.getClass() != this.getClass()) return false; if (!super.equals(o)) return false; final Person other = (Person)o; if (this.name == null ? other.name != null : !this.name.equals(other.name)) return false; if (this.gender == null ? other.gender != null : !this.gender.equals(other.gender)) return false; if (this.ssn == null ? other.ssn != null : !this.ssn.equals(other.ssn)) return false; return true; } @java.lang.Override public int hashCode() { final int PRIME = 31; int result = 1; result = result * PRIME + super.hashCode(); result = result * PRIME + (this.name == null ? 0 : this.name.hashCode()); result = result * PRIME + (this.gender == null ? 0 : this.gender.hashCode()); result = result * PRIME + (this.ssn == null ? 0 : this.ssn.hashCode()); return result; }} @Data
Lombok 代码：
@Data(staticConstructor="of")public class Company { private final Person founder; private String name; private List employees;} 等价于 Java 源码：
public class Company { private final Person founder; private String name; private List employees; private Company(final Person founder) { this.founder = founder; } public static Company of(final Person founder) { return new Company(founder); } public Person getFounder() { return founder; } public String getName() { return name; } public void setName(final String name) { this.name = name; } public List getEmployees() { return employees; } public void setEmployees(final List employees) { this.employees = employees; } @java.lang.Override public boolean equals(final java.lang.Object o) { if (o == this) return true; if (o == null) return false; if (o.getClass() != this.getClass()) return false; final Company other = (Company)o; if (this.founder == null ? other.founder != null : !this.founder.equals(other.founder)) return false; if (this.name == null ? other.name != null : !this.name.equals(other.name)) return false; if (this.employees == null ? other.employees != null : !this.employees.equals(other.employees)) return false; return true; } @java.lang.Override public int hashCode() { final int PRIME = 31; int result = 1; result = result * PRIME + (this.founder == null ? 0 : this.founder.hashCode()); result = result * PRIME + (this.name == null ? 0 : this.name.hashCode()); result = result * PRIME + (this.employees == null ? 0 : this.employees.hashCode()); return result; } @java.lang.Override public java.lang.String toString() { return "Company(founder=" + founder + ", name=" + name + ", employees=" + employees + ")"; }} @Cleanup
Lombok 代码：
public void testCleanUp() { try { @Cleanup ByteArrayOutputStream baos = new ByteArrayOutputStream(); baos.write(new byte[] {'Y','e','s'}); System.out.println(baos.toString()); } catch (IOException e) { e.printStackTrace(); }} 等价于 Java 源码：
public void testCleanUp() { try { ByteArrayOutputStream baos = new ByteArrayOutputStream(); try { baos.write(new byte[]{'Y', 'e', 's'}); System.out.println(baos.toString()); } finally { baos.close(); } } catch (IOException e) { e.printStackTrace(); }} @Synchronized
Lombok 代码：
private DateFormat format = new SimpleDateFormat("MM-dd-YYYY");@Synchronizedpublic String synchronizedFormat(Date date) { return format.format(date);} 等价于 Java 源码：
private final java.lang.Object $lock = new java.lang.Object[0];private DateFormat format = new SimpleDateFormat("MM-dd-YYYY");public String synchronizedFormat(Date date) { synchronized ($lock) { return format.format(date); }} @SneakyThrows
Lombok 代码：
@SneakyThrowspublic void testSneakyThrows() { throw new IllegalAccessException();} 等价于 Java 源码：
public void testSneakyThrows() { try { throw new IllegalAccessException(); } catch (java.lang.Throwable $ex) { throw lombok.Lombok.sneakyThrow($ex); }} 示例
使用 Lombok 定义一个 Java Bean
import lombok.Data;import lombok.ToString;@Data@ToString(exclude = "age")public class Person { private String name; private Integer age; private String sex;} 测试
Person person = new Person();person.setName("张三");person.setAge(20);person.setSex("男");System.out.println(person.toString());// output: Person(name=张三, sex=男) 示例源码
完整示例：
引用和引申
引申
参考