【Lombok】lombok使用教程

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

     <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.8</version>
    </dependency>

 

编译

     <build>
      <plugins>
          <plugin>
              <groupId>org.projectlombok</groupId>
              <artifactId>lombok-maven-plugin</artifactId>
              <version>1.16.6.1</version>
          </plugin>
      </plugins>
    </build>

 

 

  • 安装插件 

常用注解：

java bean相关

@Setter

  • 功能

    生成setter方法

  • 源码

    @Setter
        public class LombokDemo {

            private Integer id;
            private String name;
        }

 

  • 编译后

  package xyz.mrwood.study.lombok;

  public class LombokDemo {
      private Integer id;
      private String name;

      public LombokDemo() {
      }

      public void setId(Integer id) {
          this.id = id;
      }

      public void setName(String name) {
          this.name = name;
      }
  }

 

@Getter

  • 功能

    生成getter方法

  • 源码

@Getter
public class LombokDemo {

  private Integer id;
  private String name;
}

 

  • 编译后
package xyz.mrwood.study.lombok;

public class LombokDemo {
    private Integer id;
    private String name;

    public LombokDemo() {
    }

    public Integer getId() {
        return this.id;
    }

    public String getName() {
        return this.name;
    }
}

​

@ToString

    • 功能

      生成toString方法

    • 源码

      @ToString
public class LombokDemo {

  private Integer id;
  private String name;
}

 

  • 编译后
  • package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }

  public String toString() {
      return "LombokDemo(id=" + this.id + ", name=" + this.name + ")";
  }
}

@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

    public class LombokDemo {

  @Getter(lazy = true) private final List<Integer> ids = Arrays.asList(1, 2, 3, 4);
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;

public class LombokDemo {
  private final AtomicReference<Object> ids = new AtomicReference();
  private String name;

  public LombokDemo() {
  }

  public List<Integer> getIds() {
      Object value = this.ids.get();
      if(value == null) {
          AtomicReference var2 = this.ids;
          synchronized(this.ids) {
              value = this.ids.get();
              if(value == null) {
                  List actualValue = Arrays.asList(new Integer[]{Integer.valueOf(1), Integer.valueOf(2), Integer.valueOf(3), Integer.valueOf(4)});
                  value = actualValue == null?this.ids:actualValue;
                  this.ids.set(value);
              }
          }
      }

      return (List)((List)(value == this.ids?null:value));
  }
}

@EqualsAndHashCode

  • 功能

    生成equals方法与hashCode方法

  • 源码

@EqualsAndHashCode
public class LombokDemo {

    private Integer id;
    private String name;
}

 

  • 编译后
package xyz.mrwood.study.lombok;

public class LombokDemo {
    private Integer id;
    private String name;

    public LombokDemo() {
    }

    public boolean equals(Object o) {
        if(o == this) {
            return true;
        } else if(!(o instanceof LombokDemo)) {
            return false;
        } else {
            LombokDemo other = (LombokDemo)o;
            if(!other.canEqual(this)) {
                return false;
            } else {
                Integer this$id = this.id;
                Integer other$id = other.id;
                if(this$id == null) {
                    if(other$id != null) {
                        return false;
                    }
                } else if(!this$id.equals(other$id)) {
                    return false;
                }

                String this$name = this.name;
                String other$name = other.name;
                if(this$name == null) {
                    if(other$name != null) {
                        return false;
                    }
                } else if(!this$name.equals(other$name)) {
                    return false;
                }

                return true;
            }
        }
    }

    protected boolean canEqual(Object other) {
        return other instanceof LombokDemo;
    }

    public int hashCode() {
        boolean PRIME = true;
        byte result = 1;
        Integer $id = this.id;
        int result1 = result * 59 + ($id == null?43:$id.hashCode());
        String $name = this.name;
        result1 = result1 * 59 + ($name == null?43:$name.hashCode());
        return result1;
    }
}

​

@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

    @NoArgsConstructor
public class LombokDemo {

  private Integer id;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }
}

@AllArgsConstructor

    • 功能

      添加一个所有参数的构造函数

    • 源码

      @AllArgsConstructor
public class LombokDemo {

  private Integer id;
  private String name;
}
      • 编译后
package xyz.mrwood.study.lombok;

import java.beans.ConstructorProperties;

public class LombokDemo {
  private Integer id;
  private String name;

  @ConstructorProperties({"id", "name"})
  public LombokDemo(Integer id, String name) {
      this.id = id;
      this.name = name;
  }
}
    ​

@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

      @RequiredArgsConstructor
public class LombokDemo {

  @NonNull private Integer id;
  private String name;
}
      • 编译后
package xyz.mrwood.study.lombok;

import java.beans.ConstructorProperties;
import lombok.NonNull;

public class LombokDemo {
  @NonNull
  private Integer id;
  private String name;

  @ConstructorProperties({"id"})
  public LombokDemo(@NonNull Integer id) {
      if(id == null) {
          throw new NullPointerException("id");
      } else {
          this.id = id;
      }
  }
}

​

@Date

  • 功能

    这是一个综合注解了，等于同时使用

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

  • 源码

    @Data
public class LombokDemo {

  @NonNull private Integer id;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }

  public Integer getId() {
      return this.id;
  }

  public String getName() {
      return this.name;
  }

  public void setId(Integer id) {
      this.id = id;
  }

  public void setName(String name) {
      this.name = name;
  }

  public boolean equals(Object o) {
      if(o == this) {
          return true;
      } else if(!(o instanceof LombokDemo)) {
          return false;
      } else {
          LombokDemo other = (LombokDemo)o;
          if(!other.canEqual(this)) {
              return false;
          } else {
              Integer this$id = this.getId();
              Integer other$id = other.getId();
              if(this$id == null) {
                  if(other$id != null) {
                      return false;
                  }
              } else if(!this$id.equals(other$id)) {
                  return false;
              }

              String this$name = this.getName();
              String other$name = other.getName();
              if(this$name == null) {
                  if(other$name != null) {
                      return false;
                  }
              } else if(!this$name.equals(other$name)) {
                  return false;
              }

              return true;
          }
      }
  }

  protected boolean canEqual(Object other) {
      return other instanceof LombokDemo;
  }

  public int hashCode() {
      boolean PRIME = true;
      byte result = 1;
      Integer $id = this.getId();
      int result1 = result * 59 + ($id == null?43:$id.hashCode());
      String $name = this.getName();
      result1 = result1 * 59 + ($name == null?43:$name.hashCode());
      return result1;
  }

  public String toString() {
      return "LombokDemo(id=" + this.getId() + ", name=" + this.getName() + ")";
  }
}

@Value

  • 功能

    不可变类的@Date, 他会默认给属性加上final

  • 源码

    @Value
public class LombokDemo {

  private Integer id;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.beans.ConstructorProperties;

public final class LombokDemo {
  private final Integer id;
  private final String name;

  @ConstructorProperties({"id", "name"})
  public LombokDemo(Integer id, String name) {
      this.id = id;
      this.name = name;
  }

  public Integer getId() {
      return this.id;
  }

  public String getName() {
      return this.name;
  }

  public boolean equals(Object o) {
      if(o == this) {
          return true;
      } else if(!(o instanceof LombokDemo)) {
          return false;
      } else {
          LombokDemo other = (LombokDemo)o;
          Integer this$id = this.getId();
          Integer other$id = other.getId();
          if(this$id == null) {
              if(other$id != null) {
                  return false;
              }
          } else if(!this$id.equals(other$id)) {
              return false;
          }

          String this$name = this.getName();
          String other$name = other.getName();
          if(this$name == null) {
              if(other$name != null) {
                  return false;
              }
          } else if(!this$name.equals(other$name)) {
              return false;
          }

          return true;
      }
  }

  public int hashCode() {
      boolean PRIME = true;
      byte result = 1;
      Integer $id = this.getId();
      int result1 = result * 59 + ($id == null?43:$id.hashCode());
      String $name = this.getName();
      result1 = result1 * 59 + ($name == null?43:$name.hashCode());
      return result1;
  }

  public String toString() {
      return "LombokDemo(id=" + this.getId() + ", name=" + this.getName() + ")";
  }
}

@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

      @Accessors(chain = true)
@Setter
@Getter
public class LombokDemo {

  private Integer id;
  private String name;
}

 

编译后 chain = true

package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }

  public LombokDemo setId(Integer id) {
      this.id = id;
      return this;
  }

  public LombokDemo setName(String name) {
      this.name = name;
      return this;
  }

  public Integer getId() {
      return this.id;
  }

  public String getName() {
      return this.name;
  }
}

  • 源码 fluent = true

    @Accessors(fluent = true)
@Setter
@Getter
public class LombokDemo {

  private Integer id;
  private String name;
}

  • 编译后 fluent = true

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }

  public LombokDemo id(Integer id) {
      this.id = id;
      return this;
  }

  public LombokDemo name(String name) {
      this.name = name;
      return this;
  }

  public Integer id() {
      return this.id;
  }

  public String name() {
      return this.name;
  }
}

  • 源码 prefix = "xxx"

    @Accessors(prefix = "xxx")
@Setter
@Getter
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

  • 编译后 prefix = "xxx"

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }

  public void setId(Integer xxxId) {
      this.xxxId = xxxId;
  }

  public Integer getId() {
      return this.xxxId;
  }
}

其它注解：

日志相关

@Log4j

  • 源码

    @Log4j
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import org.apache.log4j.Logger;

public class LombokDemo {
  private static final Logger log = Logger.getLogger(LombokDemo.class);
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }
}

@CommonsLog

    • 源码

      @CommonsLog
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

 

  • 编译后

    package xyz.mrwood.study.lombok;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class LombokDemo {
  private static final Log log = LogFactory.getLog(LombokDemo.class);
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }
}

@Log

  • 源码

    @Log
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.util.logging.Logger;

public class LombokDemo {
  private static final Logger log = Logger.getLogger(LombokDemo.class.getName());
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }
}

@Log4j2

  • 源码

    @Log4j2
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class LombokDemo {
  private static final Logger log = LogManager.getLogger(LombokDemo.class);
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }
}

@Slf4j

  • 源码

    @Slf4j
public class LombokDemo {

  private Integer xxxId;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LombokDemo {
  private static final Logger log = LoggerFactory.getLogger(LombokDemo.class);
  private Integer xxxId;
  private String name;

  public LombokDemo() {
  }
}

设计模式相关

@Builder

  • 功能

    通过建造者模块来生成bean

  • 源码

    @Builder
public class LombokDemo {

  private Integer id;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  LombokDemo(Integer id, String name) {
      this.id = id;
      this.name = name;
  }

  public static LombokDemo.LombokDemoBuilder builder() {
      return new LombokDemo.LombokDemoBuilder();
  }

  public static class LombokDemoBuilder {
      private Integer id;
      private String name;

      LombokDemoBuilder() {
      }

      public LombokDemo.LombokDemoBuilder id(Integer id) {
          this.id = id;
          return this;
      }

      public LombokDemo.LombokDemoBuilder name(String name) {
          this.name = name;
          return this;
      }

      public LombokDemo build() {
          return new LombokDemo(this.id, this.name);
      }

      public String toString() {
          return "LombokDemo.LombokDemoBuilder(id=" + this.id + ", name=" + this.name + ")";
      }
  }
}

@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

    public class LombokDemo {

  @Delegate
  private Integer id;
  private String name;
}

  • 编译后

    package xyz.mrwood.study.lombok;

public class LombokDemo {
  private Integer id;
  private String name;

  public LombokDemo() {
  }

  public byte byteValue() {
      return this.id.byteValue();
  }

  public short shortValue() {
      return this.id.shortValue();
  }

  public int intValue() {
      return this.id.intValue();
  }

  public long longValue() {
      return this.id.longValue();
  }

  public float floatValue() {
      return this.id.floatValue();
  }

  public double doubleValue() {
      return this.id.doubleValue();
  }

  public int compareTo(Integer arg0) {
      return this.id.compareTo(arg0);
  }
}

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

    public class LombokDemo {

  public void test() throws IOException {

      @Cleanup InputStream inputStream = new FileInputStream("xxx.txt");

  }

}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.Collections;

public class LombokDemo {
  public LombokDemo() {
  }

  public void test() throws IOException {
      FileInputStream inputStream = new FileInputStream("xxx.txt");
      if(Collections.singletonList(inputStream).get(0) != null) {
          inputStream.close();
      }

  }
}

@Synchronized

  • 功能

    给方法加一个同步块

  • 源码

    public class LombokDemo {

  @Synchronized
  public void test() throws IOException {

      System.out.println("test");

  }

}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.io.IOException;

public class LombokDemo {
  private final Object $lock = new Object[0];

  public LombokDemo() {
  }

  public void test() throws IOException {
      Object var1 = this.$lock;
      synchronized(this.$lock) {
          System.out.println("test");
      }
  }
}

@SneakyThrows

  • 功能

    忽略异常

  • 源码

    public class LombokDemo {

  @SneakyThrows
  public void test() {

      String s = new String("test".getBytes(), "utf-8");

  }

}

  • 编译后

    package xyz.mrwood.study.lombok;

import java.io.IOException;

public class LombokDemo {
  private final Object $lock = new Object[0];

  public LombokDemo() {
  }

  public void test() throws IOException {
      Object var1 = this.$lock;
      synchronized(this.$lock) {
          System.out.println("test");
      }
  }
}

@NonNull

  • 功能

    设置不能为空的参数

  • 源码

    public class LombokDemo {

  public void test(@NonNull String val) {

  }
}

  • 编译后

    package xyz.mrwood.study.lombok;

import lombok.NonNull;

public class LombokDemo {
    public LombokDemo() {
    }

    public void test(@NonNull String val) {
        if(val == null) {
            throw new NullPointerException("val");
        }
    }
}

  • @UtilityClass

  • 功能

    把普通类转为工具类

  • 源码

      @UtilityClass
  public class LombokDemo {

      private Integer id = 1;
      private String name = "kiwi";

      public void util(){

          System.out.println("xxx");
      }
  }

  • 编译后

    package xyz.mrwood.study.lombok;

public final class LombokDemo {
  private static Integer id = Integer.valueOf(1);
  private static String name = "kiwi";

  public static void util() {
      System.out.println("xxx");
  }

  private LombokDemo() {
      throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
  }
}

---------------------------------------------------

原文： https://blog.csdn.net/u011719271/article/details/53842420

posted @ 2018-06-16 18:24  舞羊  阅读(255)  评论(0)  编辑  收藏  举报