在JPA的@Query注解中使用limit條件(詳解)

1. 背景介紹

在@Query注解注釋的JPQL語句中寫limit語句是會報錯:unexpected token :limit near line ....

解決方法

将@Query注解中的limit語句去掉，然後傳一個PageRequest.of(offset, limit)

2. 示例代碼：

Controller.java

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping(value = "/misaka")
public class MisakaController {
  @Autowired
  private MisakaService misakaService;

  @RequestMapping(value = "/list")
  public List<Misaka> getBaselineOverview()
  {
    return misakaService.getMisaka();
  }
}           

Service.java

import java.util.List;

public interface MisakaService {
  List<Misaka> getMisaka();
}           

Serviceimpl.java

import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.stereotype.Service;

@Service
public class MisakaServiceImpl implements MisakaService
{
  @Autowired
  private MisakaDao misakaDao;

  @Override
  public List<Misaka> getMisaka()
  {
    Pageable pageable = new PageRequest(1, 2, Direction.ASC, "name");
    Page<Misaka> misakaPage = misakaDao.search(pageable);
    List<Misaka> misakaList = misakaPage.getContent();
    System.out.println(misakaList);
    return misakaList;
  }
}           

Dao.java

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;

public interface MisakaDao extends CrudRepository<Misaka, Long>
{
	@Query("SELECT m FROM Misaka m WHERE m.id>4")
	Page<Misaka> search(Pageable pageable);

	/**
     * 分頁查詢功能
     */
    @Query("SELECT c FROM Misaka c where c.name=?1")
    List<Misaka> findUserByPage(String name, Pageable pageable);

    @Query("SELECT m FROM Misaka m WHERE m.id>4")
    Page<Misaka> findUserByPage2(Pageable pageable);
}           

Model.java

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "t_test")
public class Misaka
{
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;

  @Column(name = "name")
  private String name;

  public Long getId()
  {
    return id;
  }

  public void setId(Long id)
  {
    this.id = id;
  }

  public String getName()
  {
    return name;
  }

  public void setName(String name)
  {
    this.name = name;
  }

  @Override
  public String toString()
  {
    return "Misaka [id=" + id + ", name=" + name + "]";
  }
}           

資料庫t_test

id	name
1	m1
2	m2
3	m3
4	m4
5	m5
6	m6
7	m7
8	m8
9	m9

輸出

Hibernate: select count(misaka0_.id) as col_0_0_ from t_test misaka0_ where misaka0_.id>4

Hibernate: select misaka0_.id as id1_29_, misaka0_.name as name2_29_ from t_test misaka0_ where misaka0_.id>4 order by misaka0_.name asc limit ?, ?

[Misaka [id=7, name=m7], Misaka [id=8, name=m8]]