继承spring-data-jpa 的paSpecificationExecutor实现条件查询

dao:

package com.tensquare.base.dao;
import com.tensquare.base.pojo.Lable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
public interface LableDao extends JpaRepository<Lable,String>, JpaSpecificationExecutor<Lable> {

}

service：

/**
 * 动态条件构建 提取出单独的方法 为了方便调用
 * @param
 * @return
 */
private Specification<Lable> createSpecification(Lable lable) {

    return new Specification<Lable>() {

        @Override
        public Predicate toPredicate(Root<Lable> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
            //用于暂时存放查询条件的集合
            ArrayList<Predicate> list = new ArrayList<>();
            if (lable.getLabelname()!=null&&!"".equals(lable.getLabelname())){
                Predicate predicate = cb.like(root.get("labelname"), "%" + lable.getLabelname() + "%");//where labelname like %xxx%
                list.add(predicate);
            }
            if (lable.getState()!=null&&!"".equals(lable.getState())){
                Predicate predicate = cb.equal(root.get("state"),  lable.getState() );//where state = xxx
                list.add(predicate);
            }
            //最终将查询条件拼好然后return
            Predicate[] predicates = new Predicate[list.size()];
            return cb.and( list.toArray(predicates));//where labelname like %xxx% and state = xxx

        }
    };

}

不分页：

public List<Lable> findSearch(Lable lable) {
    //Spring Data JPA使用JpaSpecificationExecutor构建条件查询
    return lableDao.findAll(createSpecification(lable));
}

分页：
public Page<Lable> pageQuery(int pageNum, int size, Lable lable) {
    //封装分页对象
    Pageable pageable = PageRequest.of(pageNum - 1, size);
    return lableDao.findAll(createSpecification(lable),pageable);
}



controller：

@RequestMapping(value = "/search",method = RequestMethod.POST)
public Result findSearch(@RequestBody Lable lable){
    List<Lable> lables = lableService.findSearch(lable);
    return new Result(true,StatusCode.OK,"查询成功",lables);
}

@RequestMapping(value = "/search/{pageNum}/{size}",method = RequestMethod.POST)
public Result pageQuery(@PathVariable int pageNum,@PathVariable int size,@RequestBody Lable lable){
    Page<Lable> pages = lableService.pageQuery(pageNum,size,lable);
    return new Result(true,StatusCode.OK,"查询成功",new PageResult<Lable>(pages.getTotalElements(),pages.getContent()));
}

原文地址：https://www.cnblogs.com/gdut-lss/p/11520072.html