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>

idea

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;
      }
  }
}

参考 https://blog.csdn.net/u011719271/article/details/53842420#sneakythrows

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最后编辑时间为: 2018/09/02 23:26

lombok：bean注解1

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

编译

idea

常用注解：

java bean相关

@Setter

@Getter

@ToString

@Getter(lazy = true)

@EqualsAndHashCode

@NoAragsConstructor

@AllArgsConstructor

@RequiredArgsConstructor