SpringBoot-36-开发实战JPA的使用(一对多)@OneToMany+@ManyToOne
文章目录
- 1 配置
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- 1.1 pom.xml
- 1.2 application.properties
- 2 示例应用(一对多)
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- 2.1 entity
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- 2.1.1 Employee.java
- 2.1.2 Department.java
- 2.2 dao
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- 2.2.1 EmployeeDao.java
- 2.2.2 DepartmentDao.java
- 2.3 EmployeeDaoTest.java
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- 2.3.1 testAddWithEmp()(继承)
- 2.3.2 testSearch()(继承)
使用@OneToMany + @ManyToOne实现双向关联。可以(单向一对多)，但不推荐。单向@OneToMany会额外生成一个中间连接表(join table)，效率较低。而通过@ManyToOne维护外键更符合常规数据库设计。
1 配置
1.1 pom.xml
<dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>org.springframework</groupId><artifactId>spring-aspects</artifactId></dependency><dependency>