Springboot使用Specification连表查询LEFT
作者：互联网
大致目录机构
package com.frank.leftQuery.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
/**
* @author 小石潭记
* @date 2020/12/12 18:32
* @Description: ${todo}
*/
@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "t_student")
public class Student {
@Id
private Long id;
private String name;
private String address;
private String accountNumber;
private String grade;
}
package com.frank.leftQuery.entity;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import javax.persistence.*;
import java.util.List;
/**
* @author 小石潭记
* @date 2020/12/12 18:36
* @Description: ${todo}
*/
@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
@Table(name = "t_teacher")
public class Teacher {
@Id
@GeneratedValue
private Long id;
private String name;
private String address;
private String accountNumber;
// 一个老师下面有很多个学生 根据账号关联的
@OneToMany
// 由于没有使用外键 所以才使用了关联表 关联的列列名必须是两个表名_id
@JoinTable(name = "t_student_t_teacher",
joinColumns = {@JoinColumn(name = "t_teacher_id")},
inverseJoinColumns = {@JoinColumn(name = "t_student_id")})
private List<Student> studentList;
}package com.frank.leftQuery.repository;
import com.frank.leftQuery.entity.Teacher;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.stereotype.Component;
/**
* @author 小石潭记
* @date 2020/12/12 14:21
* @Description: ${todo}
*/
@Component
public interface TeacherRepository extends PagingAndSortingRepository<Teacher, Integer>, JpaSpecificationExecutor<Teacher> {
}
package com.frank.leftQuery.repository;
import com.frank.leftQuery.entity.Student;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.springframework.data.repository.PagingAndSortingRepository;
import org.springframework.stereotype.Component;
/**
* @author 小石潭记
* @date 2020/12/12 14:21
* @Description: ${todo}
*/
@Component
public interface TStudentRepository extends PagingAndSortingRepository<Student, Integer>, JpaSpecificationExecutor<Student> {
}
package com.frank.leftQuery.service;
import com.frank.leftQuery.domain.TeacherRequest;
import com.frank.leftQuery.entity.Teacher;
import com.frank.leftQuery.repository.TeacherRepository;
import com.frank.leftQuery.specification.TeacherSpecification;
import org.apache.commons.lang.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.stereotype.Service;
/**
* @author 小石潭记
* @date 2020/12/12 14:22
* @Description: ${todo}
*/
@Service
public class TeacherService {
@Autowired
private TeacherRepository teacherRepository;
@Autowired
private TeacherSpecification teacherSpecification;
public Page<Teacher> getTeacherList(TeacherRequest request) {
PageRequest pageRequest = PageRequest.of(0, 10);
return teacherRepository.findAll(teacherSpecification.getTeacherSpecification(request), pageRequest);
}
}
package com.frank.leftQuery.specification;
import com.frank.jpaSpecification.entity.PageStudentRequest;
import com.frank.leftQuery.domain.TeacherRequest;
import com.frank.leftQuery.entity.Teacher;
import com.frank.leftQuery.entity.Student;
import org.apache.commons.lang.StringUtils;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Component;
import javax.persistence.criteria.Join;
import javax.persistence.criteria.JoinType;
import javax.persistence.criteria.Predicate;
import java.util.ArrayList;
import java.util.List;
/**
* @author 小石潭记
* @date 2020/12/12 14:27
* @Description: ${todo}
*/
@Component
public class TeacherSpecification {
/**
* root 就是mobile实例 root.get("name") name是属性名 不是数据库字段名
* @param
* @return
* */
public Specification<Teacher> getTeacherSpecification(TeacherRequest request) {
return (root, criteriaQuery, criteriaBuilder) -> {
List<Predicate> predicateList = new ArrayList<>();
// 主表老师的筛选生效的
// 筛选教师名字
if (StringUtils.isNotBlank(request.getName())) {
Predicate teacherPre = criteriaBuilder.equal(root.get("name"), request.getName());
predicateList.add(teacherPre);
}
// 筛选账户号
if (StringUtils.isNotBlank(request.getAccountNumber())) {
Predicate teacherPre = criteriaBuilder.equal(root.get("accountNumber"), request.getAccountNumber());
predicateList.add(teacherPre);
}
// 使用左连接查询
Join<Teacher, Student> teacherJoin = root.join("studentList", JoinType.LEFT);
// todo 关联表 学生表的筛选未生效
if (StringUtils.isNotBlank(request.getAccountNumber())) {
Predicate studentPre = criteriaBuilder.equal(teacherJoin.get("accountNumber"), request.getAccountNumber());
predicateList.add(studentPre);
}
if (StringUtils.isNotBlank(request.getStudentName())) {
Predicate studentPre = criteriaBuilder.equal(teacherJoin.get("name"), request.getStudentName());
predicateList.add(studentPre);
}
if (StringUtils.isNotBlank(request.getGrade())) {
Predicate studentPre = criteriaBuilder.equal(teacherJoin.get("grade"), request.getGrade());
predicateList.add(studentPre);
}
// 去重
criteriaQuery.distinct(true);
return criteriaQuery.where(predicateList.toArray(new Predicate[predicateList.size()])).getRestriction();
};
}
}
package com.frank.leftQuery.domain;
import lombok.Data;
/**
* @author 小石潭记
* @date 2021/4/23 22:49
* @Description: ${todo}
*/
@Data
public class TeacherRequest {
private String name;
private String accountNumber;
private String studentName;
private String grade;
}
package com.frank.leftQuery.controller;
import com.frank.leftQuery.domain.TeacherRequest;
import com.frank.leftQuery.entity.Teacher;
import com.frank.leftQuery.service.TeacherService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* @author 小石潭记
* @date 2020/12/12 19:02
* @Description: ${todo}
*/
@RestController
@RequestMapping("/teacher")
public class TeacherController {
@Autowired
private TeacherService teacherService;
@GetMapping
public Page<Teacher> index(TeacherRequest request) {
return teacherService.getTeacherList(request);
}
}
查询老师
这里会查询出关联表里的所有的学生数据
接下来筛选学生等级为A的却失效了，因为中间表值关联的两个表的id，查询的sql并不会添加学生表的条件。
由于不使用外键（阿里巴巴规范也不推荐使用外键了~~）所以创建了中间表
-- --------------------------------------------------------
-- 主机: 127.0.0.1
-- 服务器版本: 5.6.40 - MySQL Community Server (GPL)
-- 服务器操作系统: Win64
-- HeidiSQL 版本: 8.2.0.4675
-- --------------------------------------------------------
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET NAMES utf8 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
-- 导出 表 test.t_student 结构
CREATE TABLE IF NOT EXISTS `t_student` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL,
`address` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL,
`account_number` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL,
`grade` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL COMMENT '等级',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
-- 正在导出表 test.t_student 的数据：~5 rows (大约)
DELETE FROM `t_student`;
/*!40000 ALTER TABLE `t_student` DISABLE KEYS */;
INSERT INTO `t_student` (`id`, `name`, `address`, `account_number`, `grade`) VALUES
(1, '陈同学', '重庆', '1001', 'A'),
(2, '谭同学', '丰都', '1001', 'B'),
(3, '文同学', '涪陵', '1002', 'A'),
(4, '刘同学', '忠县', '1003', 'C'),
(5, '肖同学', '万州', '1002', 'A');
/*!40000 ALTER TABLE `t_student` ENABLE KEYS */;
-- 导出 表 test.t_student_t_teacher 结构
CREATE TABLE IF NOT EXISTS `t_student_t_teacher` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`t_teacher_id` int(11) NOT NULL,
`t_student_id` int(11) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
-- 正在导出表 test.t_student_t_teacher 的数据：~5 rows (大约)
DELETE FROM `t_student_t_teacher`;
/*!40000 ALTER TABLE `t_student_t_teacher` DISABLE KEYS */;
INSERT INTO `t_student_t_teacher` (`id`, `t_teacher_id`, `t_student_id`) VALUES
(1, 1, 1),
(2, 1, 2),
(3, 2, 3),
(4, 3, 4),
(5, 2, 5);
/*!40000 ALTER TABLE `t_student_t_teacher` ENABLE KEYS */;
-- 导出 表 test.t_teacher 结构
CREATE TABLE IF NOT EXISTS `t_teacher` (
`id` int(11) DEFAULT NULL,
`name` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL,
`address` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL,
`account_number` varchar(50) COLLATE utf8mb4_bin DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;
-- 正在导出表 test.t_teacher 的数据：~3 rows (大约)
DELETE FROM `t_teacher`;
/*!40000 ALTER TABLE `t_teacher` DISABLE KEYS */;
INSERT INTO `t_teacher` (`id`, `name`, `address`, `account_number`) VALUES
(1, '小明老师', '四川', '1001'),
(2, '小蓝老师', '重庆', '1002'),
(3, '小花老师', '北京', '1003');
/*!40000 ALTER TABLE `t_teacher` ENABLE KEYS */;
/*!40101 SET SQL_MODE=IFNULL(@OLD_SQL_MODE, '') */;
/*!40014 SET FOREIGN_KEY_CHECKS=IF(@OLD_FOREIGN_KEY_CHECKS IS NULL, 1, @OLD_FOREIGN_KEY_CHECKS) */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
目前该demo只支持主表的条件过滤，关联表的过滤条件未生效！！！
标签：leftQuery,Springboot,frank,Specification,连表,org,import,com,teacher 来源： https://blog.csdn.net/qq_33371766/article/details/116081587