Specification查询

1. //查询条件List
2. List<Predicate> predicateList = new ArrayList<Predicate>();
4. Specification specification = new Specification() {
5. @Override
6. public Predicate toPredicate(Root root, CriteriaQuery criteriaQuery, CriteriaBuilder criteriaBuilder) {
7. //root即是Join<>内部第一个泛型的类型，意思就是用SkuProduct与Picture通过SkuProduct的pictures左联
8. Join<SkuProduct,Picture> skuProductPictureJoin = root.join( "pictures",JoinType.INNER);
9. //添加第1个查询条件：SkuProduct的code等于skuProduct.getCode()，然后将这个criteriaBuilder的条件添加到predicateList
10. predicateList.add(criteriaBuilder.equal(root.get( "code"),skuProduct.getCode()));
11. //添加第2个条件
12. predicateList.add(criteriaBuilder.notEqual(skuProductPictureJoin.get( "pictureType"), 0));
13. //返回
14. return criteriaBuilder.and(predicateList.toArray( new Predicate[predicateList.size()]));
15. }
16. };
18. // 重要说明：Specification不支持右连接！
19. //Specification specification = new Specification() {
20. // @Override
21. // public Predicate toPredicate(Root root, CriteriaQuery criteriaQuery, CriteriaBuilder criteriaBuilder) {
22. // Join<Picture,SkuProduct> skuProductPictureJoin = root.join("pictures",JoinType.RIGHT);
23. // predicateList.add(criteriaBuilder.notEqual(root.get("pictureType"),0));
24. // predicateList.add(criteriaBuilder.equal(skuProductPictureJoin.get("code"),skuProduct.getCode()));
25. // return criteriaBuilder.and(predicateList.toArray(new Predicate[predicateList.size()]));
26. // }
27. //};
29. List<SkuProduct> results = skuProductRepository.findAll(specification);
30. if(results!= null){
31. results.stream().forEach(result->{
32. System.out.println(result);
33. });
34. }

转自： https://blog.youkuaiyun.com/trusause/article/details/78672595