import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Join;import javax.persistence.criteria.Predicate;import javax.persistence.criteria.Root;import net.sf.json.JSONObject;import net.sf.json.JsonConfig; @Action("courierAction_pageQuery") public String pageQuery() throws Exception { Pageable pageable = new PageRequest(page-1, rows); final String courierNum = model.getCourierNum(); final String company = model.getCompany(); final String type = model.getType(); final Standard standard = model.getStandard(); //相当于DetchedCriteria对象.通过specification封装过滤条件 Specification<Courier> specification = new Specification<Courier>() { @Override public Predicate toPredicate(Root<Courier> root, CriteriaQuery<?> query, CriteriaBuilder cb) { //root：根实体 query：排序，封装条件 CriteriaBuilder：Predicate断言工厂，产生Predicate对象 //添加过滤条件:添加快递员编号条件 //p1:实体中属性 p2:条件 List<Predicate> list = new ArrayList<>(); if(StringUtils.isNotBlank(courierNum)){ Predicate p1 = cb.equal(root.get("courierNum").as(String.class), courierNum); list.add(p1); } if(StringUtils.isNotBlank(company)){ Predicate p2 = cb.equal(root.get("company").as(String.class), company); list.add(p2); } if(StringUtils.isNotBlank(type)){ Predicate p3 = cb.equal(root.get("type").as(String.class), type); list.add(p3); } //sql : select * from T_COURIER t inner join t_Standard s on t.c_standard_id = s.c_id// where s.c_name = '标准一（100公斤）'; //JPQL: from Courier c inner join c.standard s where s.name = ""; if(standard!=null && StringUtils.isNotBlank(standard.getName())){ //返回关联对象 Join<Object, Object> join = root.join("standard"); Predicate p4 = cb.equal(join.get("name").as(String.class), standard.getName()); list.add(p4); } if(list.size()==0){ return null; } //list集合转为数组 Predicate[] restrictions = new Predicate[list.size()]; restrictions = list.toArray(restrictions); return cb.and(restrictions); } }; Page<Courier> page = courierService.findAll(specification, pageable); Map<String, Object> map = new HashMap<>(); map.put("total", page.getTotalElements()); map.put("rows", page.getContent()); //将fixedares集合属性排除掉，不转json JsonConfig jsonConfig = new JsonConfig(); jsonConfig.setExcludes(new String[]{"fixedAreas"}); String json = JSONObject.fromObject(map, jsonConfig).toString(); ServletActionContext.getResponse().setContentType("text/json;charset=utf-8"); ServletActionContext.getResponse().getWriter().write(json); return NONE; }Dao:public interface CourierDao extends JpaRepository<Courier, Integer>, JpaSpecificationExecutor<Courier> {}

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助~如果有疑问大家可以留言交流，谢谢大家对的支持!