Springboot如何根据实体类生成数据库表

时间:2022-05-10 00:19:27

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.zzvips.com/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

Springboot如何根据实体类生成数据库表

然后查看数据库中是否生成了对应的表:

Springboot如何根据实体类生成数据库表

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服务器之家。

原文链接:https://blog.csdn.net/qq_41988504/article/details/86073511