简介

大部分项目中都必不可少的包含数据库实体(Entity)、数据载体(dto,dataObject),而这两部分都包含着大量的没有业务逻辑的setter、getter、空参构造，同时我们一般要复写类的toString(),equals(),hashCode()方法(贫血模型)。这些工作都是重复性的工作，作为程序员，懒是必备素质之一，这些工作肯定已经有大牛封装好了处理方法,这就是lombok。

idea 安装插件，支持lombok

lombok是在编译阶段才生成相应的代码体，所以在项目中直接调用setter，getter,constructor会报错，这时候可以在IDE安装相应的插件支持lombok。这里介绍idea插件安装，eclipse请自行百度。

安装方法

  1. 进入设置页面(windows:setting,Mac:Preferences)
  2. 点击Plugin
  3. Browse repositories
  4. 搜索lombok
  5. 点击Install
  6. 安装完毕后开启注解权限才能正常使用: 
    • –>setting
    • –>Build,Execution,Deployment
    • –>Compiler
    • –>Annontation Processors
    • –>勾选Enable annotation processing
    • –> Apply
  7. 重启Idea

引入方法

gradle

  1. // https://mvnrepository.com/artifact/org.projectlombok/lombok
  2. compile group: 'org.projectlombok', name: 'lombok', version: '1.16.16'

maven

  1. <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
  2. <dependency>
  3.     <groupId>org.projectlombok</groupId>
  4.     <artifactId>lombok</artifactId>
  5.     <version>1.16.16</version>
  6. </dependency>

常用方法

@Setter

生成setter方法,final变量不包含

  1. //原始类
  2. @Setter
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "type";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     public TestEntity() {
  18.     }
  19.  
  20.     public void setName(String name) {
  21.         this.name = name;
  22.     }
  23.  
  24.     public void setAge(Integer age) {
  25.         this.age = age;
  26.     }
  27. }

@Getter

生成getter方法,final变量不包含

  1. //原始类
  2. @Getter
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     public TestEntity() {
  18.     }
  19.  
  20.     public String getName() {
  21.         return this.name;
  22.     }
  23.  
  24.     public Integer getAge() {
  25.         return this.age;
  26.     }
  27.  
  28.     public String getType() {
  29.         this.getClass();
  30.         return "person";
  31.     }
  32. }

@NoArgsConstructor

生成空参构造

  1. //原始类
  2. @NoArgsConstructor
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     public TestEntity() {
  18.     }
  19. }

@AllArgsConstructor

生成全部参数构造

  1. //原始类
  2. @AllArgsConstructor
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     @ConstructorProperties({"name", "age"})
  18.     public TestEntity(String name, Integer age) {
  19.         this.name = name;
  20.         this.age = age;
  21.     }
  22. }

@RequiredArgsConstructor

将标记为@NoNull的属性生成一个构造器

如果运行中标记为@NoNull的属性为null,会抛出空指针异常。

  1. //原始类
  2. @RequiredArgsConstructor
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.     @NonNull
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     @NonNull
  15.     private Integer age;
  16.     private final String type = "person";
  17.  
  18.     @ConstructorProperties({"age"})
  19.     public TestEntity(@NonNull Integer age) {
  20.         if(age == null) {
  21.             throw new NullPointerException("age");
  22.         } else {
  23.             this.age = age;
  24.         }
  25.     }
  26. }

@ToString

生成所有属性的toString()方法

  1. //原始类
  2. @ToString
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     public TestEntity() {
  18.     }
  19.  
  20.     public String toString() {
  21.         StringBuilder var10000 = (new StringBuilder()).append("TestEntity(name=").append(this.name).append(", age=").append(this.age).append(", type=");
  22.         this.getClass();
  23.         return var10000.append("person").append(")").toString();
  24.     }
  25. }

@EqualsAndHashCode

生成equals()方法和hashCode方法

  1. //原始类
  2. @EqualsAndHashCode
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     public TestEntity() {
  18.     }
  19.  
  20.     public boolean equals(Object o) {
  21.         if(o == this) {
  22.             return true;
  23.         } else if(!(o instanceof TestEntity)) {
  24.             return false;
  25.         } else {
  26.             TestEntity other = (TestEntity)o;
  27.             if(!other.canEqual(this)) {
  28.                 return false;
  29.             } else {
  30.                 label47: {
  31.                     String this$name = this.name;
  32.                     String other$name = other.name;
  33.                     if(this$name == null) {
  34.                         if(other$name == null) {
  35.                             break label47;
  36.                         }
  37.                     } else if(this$name.equals(other$name)) {
  38.                         break label47;
  39.                     }
  40.  
  41.                     return false;
  42.                 }
  43.  
  44.                 Integer this$age = this.age;
  45.                 Integer other$age = other.age;
  46.                 if(this$age == null) {
  47.                     if(other$age != null) {
  48.                         return false;
  49.                     }
  50.                 } else if(!this$age.equals(other$age)) {
  51.                     return false;
  52.                 }
  53.  
  54.                 this.getClass();
  55.                 String this$type = "person";
  56.                 other.getClass();
  57.                 String other$type = "person";
  58.                 if(this$type == null) {
  59.                     if(other$type != null) {
  60.                         return false;
  61.                     }
  62.                 } else if(!this$type.equals(other$type)) {
  63.                     return false;
  64.                 }
  65.  
  66.                 return true;
  67.             }
  68.         }
  69.     }
  70.  
  71.     protected boolean canEqual(Object other) {
  72.         return other instanceof TestEntity;
  73.     }
  74.  
  75.     public int hashCode() {
  76.         boolean PRIME = true;
  77.         byte result = 1;
  78.         String $name = this.name;
  79.         int result1 = result * 59 + ($name == null?43:$name.hashCode());
  80.         Integer $age = this.age;
  81.         result1 = result1 * 59 + ($age == null?43:$age.hashCode());
  82.         this.getClass();
  83.         String $type = "person";
  84.         result1 = result1 * 59 + ($type == null?43:$type.hashCode());
  85.         return result1;
  86.     }
  87. }

@Data(常用)

@Data直接修饰POJO or beans， getter所有的变量，setter所有不为final的变量。如果你不需要默认的生成方式，直接填写你需要的annotation的就可以了。默认生成的所有的annotation都是public的，如果需要不同权限修饰符可以使用AccessLevel.NONE选项。当然@Data 也可以使用staticConstructor选项生成一个静态方法。

=@Setter+@Getter+@EqualsAndHashCode+@NoArgsConstructor

  1. //原始类
  2. @Data
  3. public class TestEntity {
  4.     @Setter(AccessLevel.PRIVATE)
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12.  
  13. public class TestEntity {
  14.     private String name;
  15.     private Integer age;
  16.     private final String type = "person";
  17.  
  18.     public TestEntity() {
  19.     }
  20.  
  21.     public String getName() {
  22.         return this.name;
  23.     }
  24.  
  25.     public Integer getAge() {
  26.         return this.age;
  27.     }
  28.  
  29.     public String getType() {
  30.         this.getClass();
  31.         return "person";
  32.     }
  33.  
  34.     public void setAge(Integer age) {
  35.         this.age = age;
  36.     }
  37.  
  38.     public boolean equals(Object o) {
  39.         if(o == this) {
  40.             return true;
  41.         } else if(!(o instanceof TestEntity)) {
  42.             return false;
  43.         } else {
  44.             TestEntity other = (TestEntity)o;
  45.             if(!other.canEqual(this)) {
  46.                 return false;
  47.             } else {
  48.                 label47: {
  49.                     String this$name = this.getName();
  50.                     String other$name = other.getName();
  51.                     if(this$name == null) {
  52.                         if(other$name == null) {
  53.                             break label47;
  54.                         }
  55.                     } else if(this$name.equals(other$name)) {
  56.                         break label47;
  57.                     }
  58.  
  59.                     return false;
  60.                 }
  61.  
  62.                 Integer this$age = this.getAge();
  63.                 Integer other$age = other.getAge();
  64.                 if(this$age == null) {
  65.                     if(other$age != null) {
  66.                         return false;
  67.                     }
  68.                 } else if(!this$age.equals(other$age)) {
  69.                     return false;
  70.                 }
  71.  
  72.                 String this$type = this.getType();
  73.                 String other$type = other.getType();
  74.                 if(this$type == null) {
  75.                     if(other$type != null) {
  76.                         return false;
  77.                     }
  78.                 } else if(!this$type.equals(other$type)) {
  79.                     return false;
  80.                 }
  81.  
  82.                 return true;
  83.             }
  84.         }
  85.     }
  86.  
  87.     protected boolean canEqual(Object other) {
  88.         return other instanceof TestEntity;
  89.     }
  90.  
  91.     public int hashCode() {
  92.         boolean PRIME = true;
  93.         byte result = 1;
  94.         String $name = this.getName();
  95.         int result1 = result * 59 + ($name == null?43:$name.hashCode());
  96.         Integer $age = this.getAge();
  97.         result1 = result1 * 59 + ($age == null?43:$age.hashCode());
  98.         String $type = this.getType();
  99.         result1 = result1 * 59 + ($type == null?43:$type.hashCode());
  100.         return result1;
  101.     }
  102.  
  103.     public String toString() {
  104.         return "TestEntity(name=" + this.getName() + ", age=" + this.getAge() + ", type=" + this.getType() + ")";
  105.     }
  106.  
  107.     private void setName(String name) {
  108.         this.name = name;
  109.     }
  110. }
  111.

@Builder

构造Builder模式的结构。通过内部类Builder()进行构建对象。

  1. //原始类
  2. @Builder
  3. public class TestEntity {
  4.  
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public class TestEntity {
  13.     private String name;
  14.     private Integer age;
  15.     private final String type = "person";
  16.  
  17.     @ConstructorProperties({"name", "age"})
  18.     TestEntity(String name, Integer age) {
  19.         this.name = name;
  20.         this.age = age;
  21.     }
  22.  
  23.     public static TestEntity.TestEntityBuilder builder() {
  24.         return new TestEntity.TestEntityBuilder();
  25.     }
  26.  
  27.     public static class TestEntityBuilder {
  28.         private String name;
  29.         private Integer age;
  30.  
  31.         TestEntityBuilder() {
  32.         }
  33.  
  34.         public TestEntity.TestEntityBuilder name(String name) {
  35.             this.name = name;
  36.             return this;
  37.         }
  38.  
  39.         public TestEntity.TestEntityBuilder age(Integer age) {
  40.             this.age = age;
  41.             return this;
  42.         }
  43.  
  44.         public TestEntity build() {
  45.             return new TestEntity(this.name, this.age);
  46.         }
  47.  
  48.         public String toString() {
  49.             return "TestEntity.TestEntityBuilder(name=" + this.name + ", age=" + this.age + ")";
  50.         }
  51.     }
  52. }
  53.  
  54. //Builder模式使用方法
  55. @Test
  56. public  void test(){
  57.     TestEntity testEntity = TestEntity.builder()
  58.                     .name("java")
  59.                     .age(18)
  60.                     .build();
  61. }

@Value

与@Data相对应的@Value， 两个annotation的主要区别就是如果变量不加@NonFinal ，@Value会给所有的弄成final的。当然如果是final的话，就没有set方法了。

  1. //原始类
  2. @Value
  3. public class TestEntity {
  4.     @Setter(AccessLevel.PRIVATE)
  5.     private String name;
  6.  
  7.     private Integer age;
  8.  
  9.     private final String type = "person";
  10. }
  11. //反编译的类
  12. public final class TestEntity {
  13.     private final String name;
  14.     private final Integer age;
  15.     private final String type = "person";
  16.  
  17.     @ConstructorProperties({"name", "age"})
  18.     public TestEntity(String name, Integer age) {
  19.         this.name = name;
  20.         this.age = age;
  21.     }
  22.  
  23.     public String getName() {
  24.         return this.name;
  25.     }
  26.  
  27.     public Integer getAge() {
  28.         return this.age;
  29.     }
  30.  
  31.     public String getType() {
  32.         this.getClass();
  33.         return "person";
  34.     }
  35.  
  36.     public boolean equals(Object o) {
  37.         if(o == this) {
  38.             return true;
  39.         } else if(!(o instanceof TestEntity)) {
  40.             return false;
  41.         } else {
  42.             TestEntity other;
  43.             label44: {
  44.                 other = (TestEntity)o;
  45.                 String this$name = this.getName();
  46.                 String other$name = other.getName();
  47.                 if(this$name == null) {
  48.                     if(other$name == null) {
  49.                         break label44;
  50.                     }
  51.                 } else if(this$name.equals(other$name)) {
  52.                     break label44;
  53.                 }
  54.  
  55.                 return false;
  56.             }
  57.  
  58.             Integer this$age = this.getAge();
  59.             Integer other$age = other.getAge();
  60.             if(this$age == null) {
  61.                 if(other$age != null) {
  62.                     return false;
  63.                 }
  64.             } else if(!this$age.equals(other$age)) {
  65.                 return false;
  66.             }
  67.  
  68.             String this$type = this.getType();
  69.             String other$type = other.getType();
  70.             if(this$type == null) {
  71.                 if(other$type != null) {
  72.                     return false;
  73.                 }
  74.             } else if(!this$type.equals(other$type)) {
  75.                 return false;
  76.             }
  77.  
  78.             return true;
  79.         }
  80.     }
  81.  
  82.     public int hashCode() {
  83.         boolean PRIME = true;
  84.         byte result = 1;
  85.         String $name = this.getName();
  86.         int result1 = result * 59 + ($name == null?43:$name.hashCode());
  87.         Integer $age = this.getAge();
  88.         result1 = result1 * 59 + ($age == null?43:$age.hashCode());
  89.         String $type = this.getType();
  90.         result1 = result1 * 59 + ($type == null?43:$type.hashCode());
  91.         return result1;
  92.     }
  93.  
  94.     public String toString() {
  95.         return "TestEntity(name=" + this.getName() + ", age=" + this.getAge() + ", type=" + this.getType() + ")";
  96.     }
  97. }

@Synchronized

同步方法

  1. //原始类
  2. public class TestEntity {
  3.     private String name;
  4.  
  5.     private Integer age;
  6.  
  7.     private final String type = "person";
  8.     @Synchronized
  9.     public void write(){
  10.         //do something
  11.     }
  12. }
  13. //反编译的类
  14. public class TestEntity {
  15.     private final Object $lock = new Object[0];
  16.     private String name;
  17.     private Integer age;
  18.     private final String type = "person";
  19.  
  20.     public TestEntity() {
  21.     }
  22.  
  23.     public void write() {
  24.         Object var1 = this.$lock;
  25.         synchronized(this.$lock) {
  26.             ;
  27.         }
  28.     }
  29. }

@Cleanup @@SneakyThrows

自动调用close方法关闭资源。

  1. //原始类
  2. public class TestEntity {
  3.     private String name;
  4.  
  5.     private Integer age;
  6.  
  7.     private final String type = "person";
  8.  
  9.     @SneakyThrows
  10.     public  void  outputStream(){
  11.          @Cleanup OutputStream outputStream = new FileOutputStream(new File("/Users/hello"));
  12.     }
  13. }
  14. //反编译的类
  15. public class TestEntity {
  16.     private String name;
  17.     private Integer age;
  18.     private final String type = "person";
  19.  
  20.     public TestEntity() {
  21.     }
  22.  
  23.     public void outputStream() {
  24.         try {
  25.             FileOutputStream $ex = new FileOutputStream(new File("/Users/hello"));
  26.             if(Collections.singletonList($ex).get(0) != null) {
  27.                 $ex.close();
  28.             }
  29.  
  30.         } catch (Throwable var2) {
  31.             throw var2;
  32.         }
  33.     }
  34. }

原文链接：https://blog.csdn.net/u013225178/article/details/80721799

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