jpa是持久层框架,前身是hibernate
项目中使用:
(一)、pom.xml引入
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency>
(二)。application.yml文件配置
#环境配置 dev就是新建的application-dev.yml spring: profiles: active: dev jpa: hibernate: # create-drop的话,每次修改字段,就会把表清空 ddl-auto: update
(三)、创建实体类
@Entity public class Banner { // 这是表的主键 @Id private String id; private String name; private String description; private String img; private String title; }
运行项目,就可以在数据库创建实体类对应的表
备注:
有时候会遇到和这个错误
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path
resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed;
nested exception is org.hibernate.AnnotationException: No identifier specified for entity: com.zb.missyou.model.Banner
这是因为没有在实体类中指定主键,就是Banner里的@Id