Spring CriteriaBuilder忽略空值

Question

我为我的地理地图创建了一个CriteriaBuilder。但是这些条件不是必需的，并且可以获取空值。如果情况不同，我尝试构建不同的搜索语句，但我认为这不是最佳方法。 如果值是null，是否有更好的方式说我的CriteriaBuilder，在搜索时应忽略此值？

过滤器示例：

UserSpecification specName =
                    new UserSpecification(new SearchCriteria("name", ":", data.getName()));
UserSpecification specEnv =
                    new UserSpecification(new SearchCriteria("env", ":", data.getEnv()));

...

if(data.getEnv().isEmpty()){
    List list = gisMapRepository.findAll(Specification.where(specName));
}

Userspecification.java：

public class UserSpecification implements Specification<GeoMap> {

    private SearchCriteria criteria;
    public UserSpecification(SearchCriteria criteria) {
        this.criteria = criteria;
    }

    @Override
    public Predicate toPredicate
            (Root<GeoMap> root, CriteriaQuery<?> query, CriteriaBuilder builder) {

        if (criteria.getOperation().equalsIgnoreCase(":")) {
            if (root.get(criteria.getKey()).getJavaType() == String.class) {
                return builder.like(
                        root.<String>get(criteria.getKey()), "%" + criteria.getValue() + "%");
            } else {
                return builder.equal(root.get(criteria.getKey()), criteria.getValue());
            }
        }

    ...

Answer 1

public class UserSpecification implements Specification<GeoMap> {

    private SearchCriteria criteria;
    public UserSpecification(SearchCriteria criteria) {
        this.criteria = criteria;
    }

    @Override
    public Predicate toPredicate
            (Root<GeoMap> root, CriteriaQuery<?> query, CriteriaBuilder builder) {

        if (criteria.isEmpty()) return null;

        //.. search something

    }
}

然后

UserSpecification specName =
                    new UserSpecification(new SearchCriteria("name", ":", data.getName()));
UserSpecification specEnv =
                    new UserSpecification(new SearchCriteria("env", ":", data.getEnv()));

...

List list = gisMapRepository.findAll(Specification.where(specName).and(specEnv));