SpringBootJPAjavaBLU111的博客-

SpringBoot_JPA

1. 创建SpringBoot工程：springboot_jpa
   
   

2. 生成项目的pom文件：

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.6.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>springboot_jpa</artifactId> <version>0.0.1-SNAPSHOT</version> <name>springboot_jpa</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions> <exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId> </exclusion> </exclusions> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> 

3. 添加lombok依赖

<dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <scope>provided</scope> </dependency> 

4. 把application.properties改成application.yml，添加配置内容：

#数据库连接 spring: datasource: url: jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8&serverTimezone=GMT%2B8     username: root     password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver   jpa: show-sql: true   #在控制台中打印sql 

5. 数据库表employee表结构和内容：

表结构：

主键id自动递增

表内容：

6. 数据库表department表结构和内容：

表结构：

表内容：

7. Employee实体类

package com.example.demo.entity; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; import lombok.Data; import lombok.ToString; @Data @ToString @NoArgsConstructor @AllArgsConstructor @Entity //告诉JPA这是一个要和数据库表映射的实体类 @Table(name="employee") //用于指定和数据库中的哪个表映射 public class Employee { @Id //标识主键 @GeneratedValue(strategy = GenerationType.IDENTITY) //设置主键增长类型 private Integer id; @Column(name = "last_name") //指定属性和数据库中的哪个字段映射 private String lastName; @Column private String email; @Column private Integer gender; @Column(name = "d_id") private Integer departmentId; } 

8. EmployeeRepository接口

package com.example.demo.repos; import org.springframework.data.jpa.repository.JpaRepository; import com.example.demo.entity.Employee; /**  * 自定义Repository，继承JpaRepository  * 泛型1：要处理的实体类  * 泛型2：主键的类型  *   * @author BLU  */ public interface EmployeeRepository extends JpaRepository<Employee, Integer>{ } 

9. 测试类SpringbootJpaApplicationTests

package com.example.demo; import java.util.Optional; import org.junit.jupiter.api.Test; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import com.example.demo.entity.Employee; import com.example.demo.repos.EmployeeRepository; @SpringBootTest class SpringbootJpaApplicationTests { @Autowired  EmployeeRepository er; @Test public void test_findbyId() {   Optional<Employee> optional = er.findById(3);   System.out.println(optional); } } 

10. 运行test_findbyId()，控制台打印：

Hibernate: select employee0_.id as id1_0_0_, employee0_.d_id as d_id2_0_0_, employee0_.email as email3_0_0_, employee0_.gender as gender4_0_0_, employee0_.last_name as last_nam5_0_0_ from employee employee0_ where employee0_.id=? Optional[Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1)] 

11. 保存单个数据

@Test public void test_save1() {  Employee e = new Employee(null, "amy", "amy@gmail.com", 2, 1);  er.save(e); } 

控制台打印：

Hibernate: insert into employee (d_id, email, gender, last_name) values (?, ?, ?, ?) 

数据库增加了一条记录：

12. 保存多个数据

@Test public void test_save2() {  Employee e1 = new Employee(null, "amy1", "amy@gmail.com", 2, 1);  Employee e2 = new Employee(null, "amy2", "amy@gmail.com", 2, 1);  Employee e3 = new Employee(null, "amy3", "amy@gmail.com", 2, 1);  er.saveAll(Arrays.asList(e1,e2,e3)); } 

控制台打印：

Hibernate: insert into employee (d_id, email, gender, last_name) values (?, ?, ?, ?) Hibernate: insert into employee (d_id, email, gender, last_name) values (?, ?, ?, ?) Hibernate: insert into employee (d_id, email, gender, last_name) values (?, ?, ?, ?) 

数据库增加了3条记录：

13. 修改数据
注：添加和修改调用的都是save方法，区别是添加方法传入的id为空，修改方法传入的id为要修改的记录的id

@Test public void test_modify() {  Employee e = new Employee(1, "zs", "zs@qq.com", 2, 1);  er.save(e); } 

控制台打印：

Hibernate: select employee0_.id as id1_0_0_, employee0_.d_id as d_id2_0_0_, employee0_.email as email3_0_0_, employee0_.gender as gender4_0_0_, employee0_.last_name as last_nam5_0_0_ from employee employee0_ where employee0_.id=? Hibernate: update employee set d_id=?, email=?, gender=?, last_name=? where id=? 

数据库中的第一条记录被修改了：

14. 删除记录

@Test public void test_delete() {  er.deleteById(9); } 

控制台打印：

Hibernate: select employee0_.id as id1_0_0_, employee0_.d_id as d_id2_0_0_, employee0_.email as email3_0_0_, employee0_.gender as gender4_0_0_, employee0_.last_name as last_nam5_0_0_ from employee employee0_ where employee0_.id=? Hibernate: delete from employee where id=? 

数据库中的第9条记录被删除了

15. 查询全部数据

@Test public void test_findAll() {  List<Employee> list = er.findAll(); for(Employee e : list) {   System.out.println(e); } } 

控制台打印：

Hibernate: select employee0_.id as id1_0_, employee0_.d_id as d_id2_0_, employee0_.email as email3_0_, employee0_.gender as gender4_0_, employee0_.last_name as last_nam5_0_ from employee employee0_ Employee(id=1, lastName=zs, email=zs@qq.com, gender=2, departmentId=1) Employee(id=2, lastName=lisi, email=lisi@163.com, gender=1, departmentId=1) Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1) Employee(id=4, lastName=linda, email=linda.qq.com, gender=2, departmentId=1) Employee(id=5, lastName=ruby, email=ruby@qq.com, gender=2, departmentId=1) Employee(id=6, lastName=amy, email=amy@gmail.com, gender=2, departmentId=1) Employee(id=7, lastName=amy1, email=amy@gmail.com, gender=2, departmentId=1) Employee(id=8, lastName=amy2, email=amy@gmail.com, gender=2, departmentId=1) 

16. 查询多个数据

@Test public void test_findAllById() {  List<Employee> list = er.findAllById(Arrays.asList(2,3,4)); for(Employee e : list) {   System.out.println(e); } } 

控制台打印：

Hibernate: select employee0_.id as id1_0_, employee0_.d_id as d_id2_0_, employee0_.email as email3_0_, employee0_.gender as gender4_0_, employee0_.last_name as last_nam5_0_ from employee employee0_ where employee0_.id in (? , ? , ?) Employee(id=2, lastName=lisi, email=lisi@163.com, gender=1, departmentId=1) Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1) Employee(id=4, lastName=linda, email=linda.qq.com, gender=2, departmentId=1) 

17. 分页查询

@Test public void test_page() {  PageRequest pageRequest = PageRequest.of(0, 3);  Page<Employee> page = er.findAll(pageRequest);  System.out.println("totalpages"+page.getTotalPages());  List<Employee> list = page.getContent(); for(Employee e : list) {   System.out.println(e); } } 

控制台打印：

Hibernate: select employee0_.id as id1_0_, employee0_.d_id as d_id2_0_, employee0_.email as email3_0_, employee0_.gender as gender4_0_, employee0_.last_name as last_nam5_0_ from employee employee0_ limit ? Hibernate: select count(employee0_.id) as col_0_0_ from employee employee0_ totalpages3 Employee(id=1, lastName=zs, email=zs@qq.com, gender=2, departmentId=1) Employee(id=2, lastName=lisi, email=lisi@163.com, gender=1, departmentId=1) Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1) 

18. 排序查询（按id和gender逆序排序）
    注：这里Order要导入的包为：import org.springframework.data.domain.Sort.Order;

@Test public void test_sort() {  Order o_id = new Order(Direction.DESC,"id");  Order o_gender = new Order(Direction.DESC,"gender");  Sort sort = Sort.by(o_id,o_gender);  List<Employee> list = er.findAll(sort); for(Employee e : list) {   System.out.println(e); } } 

控制台打印：

Hibernate: select employee0_.id as id1_0_, employee0_.d_id as d_id2_0_, employee0_.email as email3_0_, employee0_.gender as gender4_0_, employee0_.last_name as last_nam5_0_ from employee employee0_ order by employee0_.id desc, employee0_.gender desc Employee(id=8, lastName=amy2, email=amy@gmail.com, gender=2, departmentId=1) Employee(id=7, lastName=amy1, email=amy@gmail.com, gender=2, departmentId=1) Employee(id=6, lastName=amy, email=amy@gmail.com, gender=2, departmentId=1) Employee(id=5, lastName=ruby, email=ruby@qq.com, gender=2, departmentId=1) Employee(id=4, lastName=linda, email=linda.qq.com, gender=2, departmentId=1) Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1) Employee(id=2, lastName=lisi, email=lisi@163.com, gender=1, departmentId=1) Employee(id=1, lastName=zs, email=zs@qq.com, gender=2, departmentId=1) 

19. 自定义接口EmployeeDao继承Repository

package com.example.demo.repos; import org.springframework.data.repository.Repository; import com.example.demo.entity.Employee; /**  * 自定义Repository，继承JpaRepository  * 泛型1：要处理的实体类  * 泛型2：主键的类型  *   * @author BLU  */ public interface EmployeeDao extends Repository<Employee, Integer>{ } 

20. 在测试类中注入EmployeeDao

@Autowired EmployeeDao eDao; 

21. 在EmployeeDao接口中添加方法：

//根据id查询 Employee findById(Integer id); //根据lastName查询 Employee findByLastName(String uname); 

22. findById测试方法：

@Test public void test_eDao_findById() {  Employee e = eDao.findById(3);  System.out.println(e); } 

控制台打印：

Hibernate: select employee0_.id as id1_0_0_, employee0_.d_id as d_id2_0_0_, employee0_.email as email3_0_0_, employee0_.gender as gender4_0_0_, employee0_.last_name as last_nam5_0_0_ from employee employee0_ where employee0_.id=? Employee(id=3, lastName=BLU, email=blu@qq.com, gender=1, departmentId=1) 

23. findByLastName方法：

@Test public void test_eDao_findByLastName() {  Employee e = eDao.findByLastName("linda");  System.out.println(e); } 

控制台打印：

Hibernate: select employee0_.id as id1_0_, employee0_.d_id as d_id2_0_, employee0_.email as email3_0_, employee0_.gender as gender4_0_, employee0_.last_name as last_nam5_0_ from employee employee0_ where employee0_.last_name=? Employee(id=4, lastName=linda, email=linda.qq.com, gender=2, departmentId=1) 

24. 符合SpringData方法定义规范的写法示例：

findByLastName ...where x.lastname = ?1  findByLastnameAndFirstname ...where x.lastname = ?1 and x.firstname = ?2  findByLastnameOrFirstname ...where x.lastname = ?1 or x.firstname = ?2   findByIdBetween ...where x.id between ?1 and ?2  findByAgeLessThan ...where x.age < ?1  findByAgeLessThanEqual ...where x.age <= ?1  findByAgeGreaterThan ...where x.age > ?1  findByAgeGreaterThanEqual ...where x.age >= ?1  findByAgeIsNull ...where x.age is null  findByAgeIsNotNull ...where x.age not null  findByLastNameLike ...where x.lastname like ?1  findByLastNameNotLike ...where x.lastname not like ?1  findByAgeOrderByLastnameDesc ...where x.age = ?1 order by x.lastname desc  findByLastNameNot ...where x.lastname <> ?1  findByAgeIn ...where x.age in ?1  findByAgeNotIn ...where x.age not in ?1  findByActiveTrue ...where x.active = true  findByActiveFalse ...where x.active = false