Lombok

作用：帮使用者提高编码效率，减少重复与冗余的代码

原理：ASM 动态修改class文件

配置

maven

依赖

  1.      <dependency>
  2.         <groupId>org.projectlombok</groupId>
  3.         <artifactId>lombok</artifactId>
  4.         <version>1.16.8</version>
  5.     </dependency>

编译

  1.      <build>
  2.       <plugins>
  3.           <plugin>
  4.               <groupId>org.projectlombok</groupId>
  5.               <artifactId>lombok-maven-plugin</artifactId>
  6.               <version>1.16.6.1</version>
  7.           </plugin>
  8.       </plugins>
  9.     </build>

idea

  • 安装插件
    lombok 基础教程 - 图1

常用注解：

java bean相关

@Setter

  • 功能

生成setter方法

  • 源码
  1.     @Setter
  2.         public class LombokDemo {
  4.             private Integer id;
  5.             private String name;
  6.         }
  • 编译后
  2.   package xyz.mrwood.study.lombok;
  4.   public class LombokDemo {
  5.       private Integer id;
  6.       private String name;
  8.       public LombokDemo() {
  9.       }
  11.       public void setId(Integer id) {
  12.           this.id = id;
  13.       }
  15.       public void setName(String name) {
  16.           this.name = name;
  17.       }
  18.   }

@Getter

  • 功能

生成getter方法

  • 源码
  1. @Getter
  2. public class LombokDemo {
  4.   private Integer id;
  5.   private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public Integer getId() {
  11.         return this.id;
  12.     }
  14.     public String getName() {
  15.         return this.name;
  16.     }
  17. }

@ToString

  • 功能

生成toString方法

  • 源码
  1. @ToString
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public String toString() {
  11.         return "LombokDemo(id=" + this.id + ", name=" + this.name + ")";
  12.     }
  13. }

@Getter(lazy = true)

  • 功能

懒加载属性

  • 注意:

这个与上面@Getter不同，那个是修饰在类上的，也可以修饰在属性上。如果有lazy=true只能修饰在属性，并且还要是private final修饰，限制很大

  • 编码
  1. public class LombokDemo {
  3.     @Getter(lazy = true) private final List<Integer> ids = Arrays.asList(1, 2, 3, 4);
  4.     private String name;
  5. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.util.Arrays;
  4. import java.util.List;
  5. import java.util.concurrent.atomic.AtomicReference;
  7. public class LombokDemo {
  8.     private final AtomicReference<Object> ids = new AtomicReference();
  9.     private String name;
  11.     public LombokDemo() {
  12.     }
  14.     public List<Integer> getIds() {
  15.         Object value = this.ids.get();
  16.         if(value == null) {
  17.             AtomicReference var2 = this.ids;
  18.             synchronized(this.ids) {
  19.                 value = this.ids.get();
  20.                 if(value == null) {
  21.                     List actualValue = Arrays.asList(new Integer[]{Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3), Integer.valueOf(4)});
  22.                     value = actualValue == null?this.ids:actualValue;
  23.                     this.ids.set(value);
  24.                 }
  25.             }
  26.         }
  28.         return (List)((List)(value == this.ids?null:value));
  29.     }
  30. }

@EqualsAndHashCode

  • 功能

生成equals方法与hashCode方法

  • 源码
  1. @EqualsAndHashCode
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public boolean equals(Object o) {
  11.         if(o == this) {
  12.             return true;
  13.         } else if(!(o instanceof LombokDemo)) {
  14.             return false;
  15.         } else {
  16.             LombokDemo other = (LombokDemo)o;
  17.             if(!other.canEqual(this)) {
  18.                 return false;
  19.             } else {
  20.                 Integer this$id = this.id;
  21.                 Integer other$id = other.id;
  22.                 if(this$id == null) {
  23.                     if(other$id != null) {
  24.                         return false;
  25.                     }
  26.                 } else if(!this$id.equals(other$id)) {
  27.                     return false;
  28.                 }
  30.                 String this$name = this.name;
  31.                 String other$name = other.name;
  32.                 if(this$name == null) {
  33.                     if(other$name != null) {
  34.                         return false;
  35.                     }
  36.                 } else if(!this$name.equals(other$name)) {
  37.                     return false;
  38.                 }
  40.                 return true;
  41.             }
  42.         }
  43.     }
  45.     protected boolean canEqual(Object other) {
  46.         return other instanceof LombokDemo;
  47.     }
  49.     public int hashCode() {
  50.         boolean PRIME = true;
  51.         byte result = 1;
  52.         Integer $id = this.id;
  53.         int result1 = result * 59 + ($id == null?43:$id.hashCode());
  54.         String $name = this.name;
  55.         result1 = result1 * 59 + ($name == null?43:$name.hashCode());
  56.         return result1;
  57.     }
  58. }

@NoAragsConstructor

  • 功能

添加一个无参构造函数

  • 注意

这个注解在没有其它有参构造函数的情况下使用意义不大，因为在这种情况下java默认会添加一个无参构造函数

  • 源码
  1. @NoArgsConstructor
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  9. }

@AllArgsConstructor

  • 功能

添加一个所有参数的构造函数

  • 源码
  1. @AllArgsConstructor
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.beans.ConstructorProperties;
  5. public class LombokDemo {
  6.     private Integer id;
  7.     private String name;
  9.     @ConstructorProperties({"id", "name"})
  10.     public LombokDemo(Integer id, String name) {
  11.         this.id = id;
  12.         this.name = name;
  13.     }
  14. }

@RequiredArgsConstructor

  • 功能

生成一个包含必填参数的构造函数

  • 注意

要与@NonNull 搭配使用，该注解修饰的属性就是必填参数

  • 源码
  1. @RequiredArgsConstructor
  2. public class LombokDemo {
  4.     @NonNull private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.beans.ConstructorProperties;
  4. import lombok.NonNull;
  6. public class LombokDemo {
  7.     @NonNull
  8.     private Integer id;
  9.     private String name;
  11.     @ConstructorProperties({"id"})
  12.     public LombokDemo(@NonNull Integer id) {
  13.         if(id == null) {
  14.             throw new NullPointerException("id");
  15.         } else {
  16.             this.id = id;
  17.         }
  18.     }
  19. }

@Data

  • 功能

这是一个综合注解了，等于同时使用

@Getter, @Setter, @ToString, @EqualsAndHashCode,@RequiredArgsConstructor

  • 源码
  1. @Data
  2. public class LombokDemo {
  4.     @NonNull private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public Integer getId() {
  11.         return this.id;
  12.     }
  14.     public String getName() {
  15.         return this.name;
  16.     }
  18.     public void setId(Integer id) {
  19.         this.id = id;
  20.     }
  22.     public void setName(String name) {
  23.         this.name = name;
  24.     }
  26.     public boolean equals(Object o) {
  27.         if(o == this) {
  28.             return true;
  29.         } else if(!(o instanceof LombokDemo)) {
  30.             return false;
  31.         } else {
  32.             LombokDemo other = (LombokDemo)o;
  33.             if(!other.canEqual(this)) {
  34.                 return false;
  35.             } else {
  36.                 Integer this$id = this.getId();
  37.                 Integer other$id = other.getId();
  38.                 if(this$id == null) {
  39.                     if(other$id != null) {
  40.                         return false;
  41.                     }
  42.                 } else if(!this$id.equals(other$id)) {
  43.                     return false;
  44.                 }
  46.                 String this$name = this.getName();
  47.                 String other$name = other.getName();
  48.                 if(this$name == null) {
  49.                     if(other$name != null) {
  50.                         return false;
  51.                     }
  52.                 } else if(!this$name.equals(other$name)) {
  53.                     return false;
  54.                 }
  56.                 return true;
  57.             }
  58.         }
  59.     }
  61.     protected boolean canEqual(Object other) {
  62.         return other instanceof LombokDemo;
  63.     }
  65.     public int hashCode() {
  66.         boolean PRIME = true;
  67.         byte result = 1;
  68.         Integer $id = this.getId();
  69.         int result1 = result * 59 + ($id == null?43:$id.hashCode());
  70.         String $name = this.getName();
  71.         result1 = result1 * 59 + ($name == null?43:$name.hashCode());
  72.         return result1;
  73.     }
  75.     public String toString() {
  76.         return "LombokDemo(id=" + this.getId() + ", name=" + this.getName() + ")";
  77.     }
  78. }

@Value

  • 功能

不可变类的@Data, 他会默认给属性加上final

  • 源码
  1. @Value
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.beans.ConstructorProperties;
  5. public final class LombokDemo {
  6.     private final Integer id;
  7.     private final String name;
  9.     @ConstructorProperties({"id", "name"})
  10.     public LombokDemo(Integer id, String name) {
  11.         this.id = id;
  12.         this.name = name;
  13.     }
  15.     public Integer getId() {
  16.         return this.id;
  17.     }
  19.     public String getName() {
  20.         return this.name;
  21.     }
  23.     public boolean equals(Object o) {
  24.         if(o == this) {
  25.             return true;
  26.         } else if(!(o instanceof LombokDemo)) {
  27.             return false;
  28.         } else {
  29.             LombokDemo other = (LombokDemo)o;
  30.             Integer this$id = this.getId();
  31.             Integer other$id = other.getId();
  32.             if(this$id == null) {
  33.                 if(other$id != null) {
  34.                     return false;
  35.                 }
  36.             } else if(!this$id.equals(other$id)) {
  37.                 return false;
  38.             }
  40.             String this$name = this.getName();
  41.             String other$name = other.getName();
  42.             if(this$name == null) {
  43.                 if(other$name != null) {
  44.                     return false;
  45.                 }
  46.             } else if(!this$name.equals(other$name)) {
  47.                 return false;
  48.             }
  50.             return true;
  51.         }
  52.     }
  54.     public int hashCode() {
  55.         boolean PRIME = true;
  56.         byte result = 1;
  57.         Integer $id = this.getId();
  58.         int result1 = result * 59 + ($id == null?43:$id.hashCode());
  59.         String $name = this.getName();
  60.         result1 = result1 * 59 + ($name == null?43:$name.hashCode());
  61.         return result1;
  62.     }
  64.     public String toString() {
  65.         return "LombokDemo(id=" + this.getId() + ", name=" + this.getName() + ")";
  66.     }
  67. }

@Accessors

  • 功能

这个注解要搭配@Getter与@Setter使用，用来修改默认的setter与getter方法的形式

  • 注意

@Accessors有三个参数可以使用

  1. chain 链式的形式

  2. fluent 流式的形式

  3. prefix 生成指定前缀的属性的getter与setter方法，并且生成的getter与setter方法时会去除前缀

  • 源码 chain = true
  1. @Accessors(chain = true)
  2. @Setter
  3. @Getter
  4. public class LombokDemo {
  6.     private Integer id;
  7.     private String name;
  8. }
  • 编译后 chain = true
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public LombokDemo setId(Integer id) {
  11.         this.id = id;
  12.         return this;
  13.     }
  15.     public LombokDemo setName(String name) {
  16.         this.name = name;
  17.         return this;
  18.     }
  20.     public Integer getId() {
  21.         return this.id;
  22.     }
  24.     public String getName() {
  25.         return this.name;
  26.     }
  27. }
  • 源码 fluent = true
  1. @Accessors(fluent = true)
  2. @Setter
  3. @Getter
  4. public class LombokDemo {
  6.     private Integer id;
  7.     private String name;
  8. }
  • 编译后 fluent = true
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public LombokDemo id(Integer id) {
  11.         this.id = id;
  12.         return this;
  13.     }
  15.     public LombokDemo name(String name) {
  16.         this.name = name;
  17.         return this;
  18.     }
  20.     public Integer id() {
  21.         return this.id;
  22.     }
  24.     public String name() {
  25.         return this.name;
  26.     }
  27. }
  • 源码 prefix = "xxx"
  1. @Accessors(prefix = "xxx")
  2. @Setter
  3. @Getter
  4. public class LombokDemo {
  6.     private Integer xxxId;
  7.     private String name;
  8. }
  • 编译后 prefix = "xxx"
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public void setId(Integer xxxId) {
  11.         this.xxxId = xxxId;
  12.     }
  14.     public Integer getId() {
  15.         return this.xxxId;
  16.     }
  17. }

其它注解：

日志相关

@Log4j

  • 源码
  1. @Log4j
  2. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import org.apache.log4j.Logger;
  5. public class LombokDemo {
  6.     private static final Logger log = Logger.getLogger(LombokDemo.class);
  7.     private Integer xxxId;
  8.     private String name;
  10.     public LombokDemo() {
  11.     }
  12. }

@CommonsLog

  • 源码
  1. @CommonsLog
  2. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import org.apache.commons.logging.Log;
  4. import org.apache.commons.logging.LogFactory;
  6. public class LombokDemo {
  7.     private static final Log log = LogFactory.getLog(LombokDemo.class);
  8.     private Integer xxxId;
  9.     private String name;
  11.     public LombokDemo() {
  12.     }
  13. }

@Log

  • 源码
  1. @Log
  2. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.util.logging.Logger;
  5. public class LombokDemo {
  6.     private static final Logger log = Logger.getLogger(LombokDemo.class.getName());
  7.     private Integer xxxId;
  8.     private String name;
  10.     public LombokDemo() {
  11.     }
  12. }

@Log4j2

  • 源码
  1. @Log4j2
  2. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import org.apache.logging.log4j.LogManager;
  4. import org.apache.logging.log4j.Logger;
  6. public class LombokDemo {
  7.     private static final Logger log = LogManager.getLogger(LombokDemo.class);
  8.     private Integer xxxId;
  9.     private String name;
  11.     public LombokDemo() {
  12.     }
  13. }

@Slf4j

  • 源码
  1. @Slf4j
  2. public class LombokDemo {
  4.     private Integer xxxId;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import org.slf4j.Logger;
  4. import org.slf4j.LoggerFactory;
  6. public class LombokDemo {
  7.     private static final Logger log = LoggerFactory.getLogger(LombokDemo.class);
  8.     private Integer xxxId;
  9.     private String name;
  11.     public LombokDemo() {
  12.     }
  13. }

设计模式相关

@Builder

  • 功能

通过建造者模块来生成bean

  • 源码
  1. @Builder
  2. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     LombokDemo(Integer id, String name) {
  8.         this.id = id;
  9.         this.name = name;
  10.     }
  12.     public static LombokDemo.LombokDemoBuilder builder() {
  13.         return new LombokDemo.LombokDemoBuilder();
  14.     }
  16.     public static class LombokDemoBuilder {
  17.         private Integer id;
  18.         private String name;
  20.         LombokDemoBuilder() {
  21.         }
  23.         public LombokDemo.LombokDemoBuilder id(Integer id) {
  24.             this.id = id;
  25.             return this;
  26.         }
  28.         public LombokDemo.LombokDemoBuilder name(String name) {
  29.             this.name = name;
  30.             return this;
  31.         }
  33.         public LombokDemo build() {
  34.             return new LombokDemo(this.id, this.name);
  35.         }
  37.         public String toString() {
  38.             return "LombokDemo.LombokDemoBuilder(id=" + this.id + ", name=" + this.name + ")";
  39.         }
  40.     }
  41. }

@Delegate

  • 功能

@Delegate注释的属性，会把这个属性对象的公有非静态方法合到当前类

  • 注意

公共 非静态方法

  • 源码
  1. public class LombokDemo {
  3.     @Delegate
  4.     private Integer id;
  5.     private String name;
  6. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public class LombokDemo {
  4.     private Integer id;
  5.     private String name;
  7.     public LombokDemo() {
  8.     }
  10.     public byte byteValue() {
  11.         return this.id.byteValue();
  12.     }
  14.     public short shortValue() {
  15.         return this.id.shortValue();
  16.     }
  18.     public int intValue() {
  19.         return this.id.intValue();
  20.     }
  22.     public long longValue() {
  23.         return this.id.longValue();
  24.     }
  26.     public float floatValue() {
  27.         return this.id.floatValue();
  28.     }
  30.     public double doubleValue() {
  31.         return this.id.doubleValue();
  32.     }
  34.     public int compareTo(Integer arg0) {
  35.         return this.id.compareTo(arg0);
  36.     }
  37. }

工具相关

@Cleanup

  • 功能

关闭流

  • 注意

关闭流的方式有点怪异，而且没有在finally里面关闭，如果出现异常的就不会关闭了

  • 源码
  1. public class LombokDemo {
  3.     public void test() throws IOException {
  5.         @Cleanup InputStream inputStream = new FileInputStream("xxx.txt");
  7.     }
  9. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.io.FileInputStream;
  4. import java.io.IOException;
  5. import java.util.Collections;
  7. public class LombokDemo {
  8.     public LombokDemo() {
  9.     }
  11.     public void test() throws IOException {
  12.         FileInputStream inputStream = new FileInputStream("xxx.txt");
  13.         if(Collections.singletonList(inputStream).get(0) != null) {
  14.             inputStream.close();
  15.         }
  17.     }
  18. }

@Synchronized

  • 功能

给方法加一个同步块

  • 源码
  1. public class LombokDemo {
  3.     @Synchronized
  4.     public void test() throws IOException {
  6.         System.out.println("test");
  8.     }
  10. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.io.IOException;
  5. public class LombokDemo {
  6.     private final Object $lock = new Object[0];
  8.     public LombokDemo() {
  9.     }
  11.     public void test() throws IOException {
  12.         Object var1 = this.$lock;
  13.         synchronized(this.$lock) {
  14.             System.out.println("test");
  15.         }
  16.     }
  17. }

@SneakyThrows

  • 功能

忽略异常

  • 源码
  1. public class LombokDemo {
  3.     @SneakyThrows
  4.     public void test() {
  6.         String s = new String("test".getBytes(), "utf-8");
  8.     }
  10. }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. import java.io.IOException;
  5. public class LombokDemo {
  6.     private final Object $lock = new Object[0];
  8.     public LombokDemo() {
  9.     }
  11.     public void test() throws IOException {
  12.         Object var1 = this.$lock;
  13.         synchronized(this.$lock) {
  14.             System.out.println("test");
  15.         }
  16.     }
  17. }

@NonNull

  • 功能

设置不能为空的参数

  • 源码
  1. public class LombokDemo {
  3.     public void test(@NonNull String val) {
  5.     }
  6. }
  • 编译后
  1.   package xyz.mrwood.study.lombok;
  3.   import lombok.NonNull;
  5.   public class LombokDemo {
  6.       public LombokDemo() {
  7.       }
  9.       public void test(@NonNull String val) {
  10.           if(val == null) {
  11.               throw new NullPointerException("val");
  12.           }
  13.       }
  14.   }

@UtilityClass

  • 功能

把普通类转为工具类

  • 源码
  1.     @UtilityClass
  2.     public class LombokDemo {
  4.         private Integer id = 1;
  5.         private String name = "kiwi";
  7.         public void util(){
  9.             System.out.println("xxx");
  10.         }
  11.     }
  • 编译后
  1. package xyz.mrwood.study.lombok;
  3. public final class LombokDemo {
  4.     private static Integer id = Integer.valueOf(1);
  5.     private static String name = "kiwi";
  7.     public static void util() {
  8.         System.out.println("xxx");
  9.     }
  11.     private LombokDemo() {
  12.         throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
  13.     }
  14. }