springboot继承JPA根据实体类生成数据库中的表

r囧r小猫 2023-07-14 08:20 26阅读 0赞

***首先搭建springboot框架。搭建完成之后：***

### 1. pom中添加的依赖： ###

<dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jdbc</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.mybatis.spring.boot</groupId>
                <artifactId>mybatis-spring-boot-starter</artifactId>
                <version>2.1.1</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-data-jpa</artifactId>
            </dependency>
    
            
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.15</version>
            </dependency>
    
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <optional>true</optional>
            </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>

### 2.  application.yml中配置jpa配置 ###

server:
      port: 8080
    
    spring:
      datasource:
        type: com.zaxxer.hikari.HikariDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://localhost:3306/h5mall?useUnicode=true&characterEncoding=utf-8&useSSL=false
        username: root
        password: 123456
        hikari:
          minimum-idle: 5
          idle-timeout: 180000
          maximum-pool-size: 10
          auto-commit: true
          pool-name: MyHikariCP
          connection-timeout: 30000
      jpa:
        hibernate:
          ddl-auto: update
        show-sql: true

其中jpa下的jpa.hibernate.ddl-auto属性值有如下：

ddl-auto:create   （每次运行该程序，没有表格会新建表格，表内有数据会清空）

ddl-auto:create-drop   （每次程序结束的时候会清空表）

ddl-auto:update   （每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新）

ddl-auto:validate（运行程序会校验数据与数据库的字段类型是否相同，不同会报错）

一般情况下选择update，其他属性值慎用！

### 定义用户实体类，通过注解映射成数据库中的表 ###

import javax.persistence.*;
    
    @Entity
    @Table(name = "user")
    @Data
    public class User {
    
        @Id
        @GeneratedValue
        private Long id;
    
        //name属性为表的字段名。length为字段的长度
        @Column(length = 30, name = "userId")
        private String userId;
    
        @Column(name = "userName", length = 20, columnDefinition="varchar(100) COMMENT '用户名'")
        private String userName;
    
        @Column(name = "phone", length = 20)
        private String phone;
    
        @Column(name = "password", length = 30)
        private String password;
    
        @Column(name = "userRealName", length = 20)
        private String userRealName;
    
        @Column(name = "address", length = 20)
        private String address;
    
    }

### 启动springboot项目： ###

可看到控制台上显示了创建表中的

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NvV2hhdFdvcmxk_size_16_color_FFFFFF_t_70][]

然后查看数据库中是否生成了对应的表：

![20200313231851583.png][]

END!

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1NvV2hhdFdvcmxk_size_16_color_FFFFFF_t_70]: /images/20230529/576cde1381a64dc6ae5ed630f77cdbba.png
[20200313231851583.png]: /images/20230529/6997e47f9ac3449ab9cf97a95872b793.png