mybatis-plus注解实现非主键字段生成uuid

springboot + mybatis-plus架构下：
让非主键字段以注解方式自动生成32位uuid：

1. 自定义注解如下

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.FIELD, ElementType.ANNOTATION_TYPE})
public @interface GenerateUUID {
    String value() default "";
}

2. 在字段上的应用方式

@GenerateUUID
@TableField(fill = FieldFill.INSERT)
private String uuidCode;

其中

@TableField(fill = FieldFill.INSERT)

为mybatis-plus中设置的引用方法。引用方法设置如下：
3. 实现MetaObjectHandler接口，如上注解为insert则走insertFill方法

@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    @Override
    public void insertFill(MetaObject metaObject) {
        Object originalObject = metaObject.getOriginalObject();
        try{
            Class clazz = originalObject.getClass();
            for (Field declaredField : clazz.getDeclaredFields()) {
                declaredField.setAccessible(true);
                if (declaredField.isAnnotationPresent(GenerateUUID.class) && declaredField.get(originalObject) == null){
                    this.setFieldValByName(declaredField.getName(),IdWorker.get32UUID(),metaObject);
                }
            }
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void updateFill(MetaObject metaObject) {
    }
}