Java annotation value use enum name

2023-05-20 208 words One minute - views

Contents

1. Background

Java annotation value must be constant
But some case want to use enum name(eg. spring-cache use enum config cache, operate cache need cache name)

2. Plan

Plan 1: name property + external name interface

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@lombok.Getter
@lombok.AllArgsConstructor
public enum CommonCacheConfig {
    QUOTE_LEVEL(CommonCacheConstant.QUOTE_LEVEL, 2);

    private final String name;

    private final int ttl;
}

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public interface CommonCacheConstant {

    String QUOTE_LEVEL = "QUOTE_LEVEL";

}

Usage：@Cacheable(cacheNames = CommonCacheConstant.QUOTE_LEVEL)

Plan 2: name property + internal name interface

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public enum CommonCacheConfig {
    QUOTE_LEVEL(Constant.QUOTE_LEVEL, 2);

    private final String name;
    private final Integer ttl;

    public interface Constant {
        String QUOTE_LEVEL = "QUOTE_LEVEL";
    }
}

Usage：@Cacheable(cacheNames = CommonCacheConfig.Constant.QUOTE_LEVEL)

Plan 3：Lombok’s FieldNameConstants

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@lombok.Getter
@lombok.AllArgsConstructor
@lombok.experimental.FieldNameConstants(onlyExplicitlyIncluded = true)
public enum CommonCacheConfig {

	@FieldNameConstants.Include QUOTE_LEVEL(2);

	private final Integer ttl;

}

Usage：@Cacheable(cacheNames = CommonCacheConfig.Fields.QUOTE_LEVEL)
Attention: FieldNameConstants’s onlyExplicitlyIncluded must set to true，otherwise generate by property(eg. ttl), and add @FieldNameConstants.Include before enum item.

3. Summary

Use Lombok’s FieldNameConstants auto generate enum name constant, improved maintainability
Refer：java - Use Enum type as a value parameter for @RolesAllowed-Annotation - Stack Overflow

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