jpa的分页和条件查询分页

1.只有排序的分页

  public Page<User> find(Integer page, Integer size) {
        if (null == page) {
            page = 0;
        }
        if (size==0) {
            size = 10;
        }
        PageRequest pageable = PageRequest.of(page-1, size, Sort.Direction.DESC, "id");
        Page<User> users = userDao.findAll(pageable);
        return users;
    }

　2.带有查询条件的分页

 public Page<User> findByPageAndParams(Integer page, Integer size, User param) {
        if (null == page) {
            page = 0;
        }
        if (size == 0) {
            size = 10;
        }
        Pageable pageable = new PageRequest(page - 1, size,Sort.Direction.DESC, "id");  //分页信息
        Specification<User> spec = new Specification<User>(){
            //查询条件构造
            @Override
            public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                Path<String> name = root.get("name");
                Predicate p1 = cb.like(name, "%"+param.getName()+"%");
                Predicate p = cb.and(p1);
                return p;
            }

        };
        Page<User> users = userDao.findAll(spec, pageable);
        return users;
    }

3.dao层需要继承两个文件

public interface UserDao extends JpaSpecificationExecutor<User>,JpaRepository<User,Long> {


    @Query(value = "select * from t_user where name like  %?1%  order by id desc ", nativeQuery = true)
    List<User> getUserByLikeUserName(String userName);

    @Query(value = "select * from t_user where name = ?1", nativeQuery = true)
    List<User> getUserByUserName(String userName);


    @Query(value = "select * from t_user where id = ?1", nativeQuery = true)
    List<User> getUserByUserId(Integer id);


    @Query(value = "select * from t_user order by id  ", nativeQuery = true)
    List<User> getUserList();


    //只有排序的分页查询
    Page<User> findAll(Specification<User> spec, Pageable pageable);



}

　

这样就可以是先分页查询。

package com.example.react.service;

import com.example.react.model.User;
import com.example.react.dao.UserDao;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.*;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;

import javax.persistence.criteria.*;
import java.util.List;
import org.springframework.data.jpa.domain.*;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    public User getOne(long  id) {
        User user = new User();
        user.setId(id);
        Example<User> userExample = Example.of(user);
        return userDao.findOne(userExample).orElse(null);
    }

    @Override
    public List<User> all() {
       return  userDao.findAll();
    }

    @Override
    public Page<User> find(Integer page, Integer size) {
        if (null == page) {
            page = 0;
        }
        if (size==0) {
            size = 10;
        }
        PageRequest pageable = PageRequest.of(page-1, size, Sort.Direction.DESC, "id");
        Page<User> users = userDao.findAll(pageable);
        return users;
    }


    

    @Override
    public Page<User> findByPageAndParams(Integer page, Integer size, User param) {
        if (null == page) {
            page = 0;
        }
        if (size == 0) {
            size = 10;
        }
        Pageable pageable = new PageRequest(page - 1, size,Sort.Direction.DESC, "id");  //分页信息
        Specification<User> spec = new Specification<User>(){
            //查询条件构造
            @Override
            public Predicate toPredicate(Root<User> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
                Path<String> name = root.get("name");
                Predicate p1 = cb.like(name, "%"+param.getName()+"%");
                Predicate p = cb.and(p1);
                return p;
            }

        };
        Page<User> users = userDao.findAll(spec, pageable);
        return users;
    }

}

返回的结果：

{
  "content": [
    {
      "id": 13,
      "name": "孙文",
      "phone": "374771",
      "telPhone": "www"
    },
    {
      "id": 11,
      "name": "张君宝",
      "phone": "122",
      "telPhone": "011112"
    },
    {
      "id": 10,
      "name": "朱熹",
      "phone": "1112",
      "telPhone": "3334"
    },
    {
      "id": 9,
      "name": "朱常洛",
      "phone": " 1992933",
      "telPhone": "234444"
    },
    {
      "id": 8,
      "name": "张珊珊",
      "phone": "18037022643",
      "telPhone": "367742"
    }
  ],
  "pageable": {
    "sort": {
      "sorted": true,
      "unsorted": false
    },
    "offset": 0,
    "pageNumber": 0,
    "pageSize": 5,
    "paged": true,
    "unpaged": false
  },
  "last": false,
  "totalPages": 3,
  "totalElements": 11,
  "size": 5,
  "number": 0,
  "sort": {
    "sorted": true,
    "unsorted": false
  },
  "numberOfElements": 5,
  "first": true
}