见（digitalgd）
一、调用
Specification spec;
PredicateBuilder<HonestTalk> pb = Specifications.<HonestTalk>and()
        .eq(StringUtils.isNotBlank(sponsorOaAccount), "sponsorAccount", sponsorOaAccount)
        .eq(StringUtils.isNotBlank(oaAccount), "oaAccount", oaAccount)
        .eq(status != null, "status", status)
        .predicate(StringUtils.isNotBlank(talkedOaAccount), this.getDetailSpecification(talkedOaAccount));
String currentUserAccount = CurrentUser.getCurrentUser().getUser().getAccount();
if (this.commonService.checkHasRole(currentUserAccount, DataScopeRole.MONITOR.name())) {
    spec = pb.build();
} else {
    spec = pb.build().and(dataScopeConditionGeneratorService.generateDataScopeCondition(currentUserAccount));
}
Page<HonestTalk> honestConversationPage = repository.findAll(spec, PageHelper.generatePageRequest(page, size, sort));

二、定义
     public Specification<HonestTalk> getDetailSpecification(String talkedOaAccount) {
        return (root, criteriaQuery, criteriaBuilder) -> {
            // http://localhost:8080/student?companyName=北京&pageNumber=0&pageSize=5&name=明
            /*
            // 普通的or
            Predicate namePre = criteriaBuilder.like(root.get("name"), "%" + paramRequest.getName() + "%");
            Predicate companyPre = criteriaBuilder.like(root.get("company").get("name"), "%" + paramRequest.getCompanyName() + "%");
            return criteriaBuilder.or(namePre, companyPre);
            */

            // 使用左连接查询
            Join<HonestTalk, HonestTalkDetail> talkDetailJoin = root.join("talkDetails", JoinType.INNER);

//            Predicate namePre = criteriaBuilder.like(root.get("name"), "%" + paramRequest.getName() + "%");
            Predicate detail = criteriaBuilder.equal(talkDetailJoin.get("talkedOaAccount"), talkedOaAccount);

//            return criteriaBuilder.or(namePre, companyPre);
            return detail;

        };
    }

jpa specification 实现外连接