Springboot 实体类生成数据库表
JPA:springboot -jpa:数据库的一系列的定义数据持久化的标准的体系
学习的目的是:
利用springboot实现对数据库的操作
第一步:添加springboot-data-jpa和数据库的依赖关系
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
第二步:编写yml文件的配置
server:
port: 8001
spring:
application:
name: jih-manage
datasource:
name: test
url: jdbc:mysql://111.231.231.56/jih
username: root
password: root
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
jpa:
hibernate:
ddl-auto: update
show-sql: true
第三步:实体类中使用的注解
@Entity
实体类的注解@Id
映射到表格中id的属性@Gernertervalue
添加其自增的属性
第四步:启动项目是否生成表格
补充的知识点:
根据实体类生成数据库的表配置文件有俩种方式分别是yml和properties文件进行配置
yml文件:
spring:
datasource:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/facemap
username: root
password: root
jpa:
hibernate:
ddl-auto: update
show-sql: true
properties文件的写法:
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/dbgirl?characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.show-sql= true
spring.jpa.hibernate.ddl-auto=update
spring.jpa.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
spring.jackson.serialization.indent_output=false
有更加详细介绍
参考网址:
//www.jb51.net/article/222622.htm
实体类的写法:
package com.example.demo;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
@Entity //实体类的注解
public class Girl {
@Id //@id注意选择这个javax.persistence
@GeneratedValue
private Integer id;
private String cupSize;
private Integer age;
public Girl() {
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getCupSize() {
return cupSize;
}
public void setCupSize(String cupSize) {
this.cupSize = cupSize;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
第五步:启动项目即可
完成~
springboot继承JPA根据实体类生成数据库中的表
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>
<!--mysql-connection-->
<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
然后查看数据库中是否生成了对应的表:
以上为个人经验,希望能给大家一个参考,也希望大家多多支持编程网。