JPA多条件复杂SQL动态分页查询
概述
ORM映射为我们带来便利的同时，也失去了较大灵活性，如果SQL较复杂，要进行动态查询，那必定是一件头疼的事情（也可能是lz还没发现好的方法），记录下自己用的三种复杂查询方式。
环境
springBoot
IDEA2017.3.4
JDK8
pom.xml
4.0.0
org.springframework.boot
spring-boot-starter-parent
2.1.6.RELEASE
com.xmlxy
seasgame
0.0.1-SNAPSHOT
seasgame
Demo project for Spring Boot
1.8
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-test
test
org.springframework.boot
spring-boot-starter-data-jpa
mysql
mysql-connector-java
runtime
org.springframework.boot
spring-boot-devtools
runtime
true
org.projectlombok
lombok
true
org.springframework.boot
spring-boot-starter-data-jpa
io.springfox
springfox-swagger2
2.8.0
io.springfox
springfox-swagger-ui
2.8.0
org.springframework.boot
spring-boot-configuration-processor
true
org.springframework.boot
spring-boot-starter-security
net.sf.json-lib
json-lib
2.2.2
jdk15
com.belerweb
pinyin4j
2.5.1
org.springframework.boot
spring-boot-starter-thymeleaf
javax.servlet
javax.servlet-api
3.1.0
provided
war
org.springframework.boot
spring-boot-maven-plugin
org.apache.maven.plugins
maven-compiler-plugin
1.8
1.8
seasgame
org.apache.maven.plugins
maven-compiler-plugin
2.3.2
${project.build.sourceEncoding}
1.7
1.7
org.apache.maven.plugins
maven-surefire-plugin
true
@Query
当一个SQL较为复杂时，第一个想到的就是原生的SQL语句。如果只是简单的查询，那情况还没这么糟糕
@Query(value = " SELECT IFNULL(sum(right_num),0) sumRight FROM t_record WHERE record_owner_id = ?1 AND responder_no = ?2 ",nativeQuery = true)
Map sumRightNum(int studentId,int responderNo);
但如果需要进行动态查询，或更改，那这个value就变得复杂了。
package com.xmlxy.seasgame.dao;
import com.xmlxy.seasgame.entity.ScoreEntity;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
/**
*
* Description:
* @author hwc
* @date 2019/9/5
* @return
*/
public interface ScoreDao extends CrudRepository
{
/**
*
* Description:
*@param scoreEntity
* @author hwc
* @date 2019/9/6
*/
@Transactional(rollbackFor = Exception.class)
@Modifying
@Query(value = "UPDATE t_score t SET " +
"t.responder_no = CASE WHEN :#{#scoreEntity.responderNo} IS NULL THEN t.responder_no ELSE :#{#scoreEntity.responderNo} END," +
"t.max_level = CASE WHEN :#{#scoreEntity.maxLevel} IS NULL THEN t.max_level ELSE :#{#scoreEntity.maxLevel} END," +
"t.right_num = CASE WHEN :#{#scoreEntity.rightNum} IS NULL THEN t.right_num ELSE :#{#scoreEntity.rightNum} END," +
"t.use_time = CASE WHEN :#{#scoreEntity.userTime} IS NULL THEN t.use_time ELSE :#{#scoreEntity.userTime} END WHERE student_id = :#{#scoreEntity.getStudentId()}",nativeQuery = true)
void updateScore(@Param("scoreEntity") ScoreEntity scoreEntity);
}
JPQL
如果Java代码内发出JPQL查询，就需要利用到EntityManager的响应方法了。一般执行以下流程
获取一个EntityManager实例
调用实例的方法createQuery，创建一个Query实例，如果有需要可以指定检索的最大数量和起始位置
使用Query方法getResultList执行查询，当然更新和删除操作得使用executeUpdate执行
进行一个复杂的动态SQL查询
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public Page getScoreByRank(int gradeId,int classId,Pageable pageable)
{
StringBuilder countSelectSql = new StringBuilder("");
countSelectSql.append(" SELECT COUNT(*) ");
countSelectSql.append(" FROM ");
countSelectSql.append(" t_score s, ");
countSelectSql.append(" t_student st ");
countSelectSql.append(" WHERE ");
countSelectSql.append(" s.student_id = st.student_id ");
StringBuilder selectSql = new StringBuilder();
selectSql.append(" SELECT s.student_id,st.real_name,st.student_class,s.max_level,s.use_time,s.right_num ");
selectSql.append(" FROM t_score s ");
selectSql.append(" JOIN t_student st ON s.student_id = st.student_id ");
selectSql.append(" WHERE 1 = 1 ");
Map params = new HashMap<>();
StringBuilder whereSql = new StringBuilder();
if (gradeId != -1)
{
whereSql.append(" AND st.student_grade = :student_grade ");
params.put("student_grade",gradeId);
}
/**班级ID*/
if (classId != -1)
{
whereSql.append(" AND st.student_class = :classId ");
params.put("classId",classId);
}
String orderSql = " ORDER BY s.max_level DESC,s.use_time,s.right_num ASC ";
String countSql = new StringBuilder().append(countSelectSql).append(whereSql).toString();
Query countQuery = entityManager.createNativeQuery(countSql);
for (Map.Entry entry : params.entrySet())
{
countQuery.setParameter(entry.getKey(),entry.getValue());
}
BigInteger totalCount = (BigInteger)countQuery.getSingleResult();
String querySql = new StringBuilder().append(selectSql).append(whereSql).append(orderSql).toString();
Query query = entityManager.createNativeQuery(querySql,RankEntity.class);
for (Map.Entry entry:params.entrySet())
{
query.setParameter(entry.getKey(),entry.getValue());
}
query.setFirstResult((int) pageable.getOffset());
query.setMaxResults(pageable.getPageSize());
List rankEntities = query.getResultList();
Page page = new PageImpl<>(rankEntities,pageable,totalCount.longValue());
return page;
}
注意：如果没有重新定义Pageable那么pageNumber必须减1，因为是从0开始的。
Criteria
这是一种规范查询是以元模型的概念为基础的，这个元模型可以是实体累，嵌入类，或者映射的父类，简单介绍几个里面用到接口。
CriteraQuery是一个特定的顶层查询对象，里面包含select，from，where，order by等各个部分，然而他只对实体类或嵌入类的标准查询起作用。
Root标准查询的根对象，根定义了实体类型，是你想要查询要获得的结果，也可以添加查询条件，结合实体管理对象得到查询的对象。
CriteriaBuilder接口用来构建CritiaQuery的构建器
StudentEntity类
package com.xmlxy.seasgame.entity;
import io.swagger.annotations.ApiModel;
import lombok.Data;
import javax.persistence.*;
import javax.print.attribute.standard.MediaSize;
import java.io.Serializable;
/**
*
* Description:学生对象
* @param
* @author hwc
* @date 2019/8/8
*/
@Entity
@Table(name = "t_base_student")
@ApiModel
@Data
public class StudentEntity implements Serializable
{
private static final long serialVersionUID = 546L;
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "student_id")
private Integer studentId;
@Column(name = "student_grade")
private Integer studentGrade;
@Column(name = "student_class")
private Integer studentClass;
@Column(name = "address")
private String address;
@Column(name = "telephone")
private Integer telephone;
@Column(name = "real_name")
private String realName;
@Column(name = "id_number")
private String idNumber;
@Column(name = "study_id")
private String studyId;
@Column(name = "is_delete")
private int isDelete;
@Column(name = "uuid")
private String uuid;
}
dao层
public interface StudentDao extends JpaRepository,JpaSpecificationExecutor
{
}
动态查询
public Page getTeacherClassStudent(int pageNumber,int pageSize,int gradeId, int classId,String keyword)
{
pageNumber = pageNumber < 0 ? 0 : pageNumber;
pageSize = pageSize < 0 ? 10 : pageSize;
Specification specification = new Specification()
{
@Override
public Predicate toPredicate(Root root, CriteriaQuery criteriaQuery, CriteriaBuilder criteriaBuilder)
{
//page : 0 开始, limit : 默认为 10
List predicates = new ArrayList<>();
predicates.add(criteriaBuilder.equal(root.get("studentGrade"),gradeId));
predicates.add(criteriaBuilder.equal(root.get("studentClass"),classId));
if (!Constant.isEmptyString(keyword))
{
predicates.add(criteriaBuilder.like(root.get("realName").as(String.class),"%" + keyword + "%"));
}
return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
}
};
/*studentId必须是实体类属性与数据库对应，否则报ropertyReferenceException异常*/
PageRequest page = new PageRequest(pageNumber,pageSize,Sort.Direction.ASC,"studentId");
Page pages = studentDao.findAll(specification,page);
return pages;
}
因为这个项目应用比较简单，所以条件只有一个，如果条件较多，甚至可以定义一个专门的类去接收拼接参数，然后判断，成立就add进去。
转载一篇写得不错的文章：https://blog.csdn.net/u010775025/article/details/80497986https://www.cnblogs.com/dslx/p/11474453.html