一、Spring-Data-Jpa概念

• JPA(Java Persistence API)定义了一系列对象持久化的标准，目前实现这一规范的产品有Hibernate、TopLink等。
• Spring Data JPA 框架，主要针对的就是 Spring 唯一没有简化到的业务逻辑代码，至此，开发者连仅剩的实现持久层业务逻辑的工作都省了，唯一要做的，就只是声明持久层的接口，其他都交给 Spring Data JPA 来帮你完成！

二、自动生成表

　　2.1　　pom.xml，按代码提示键进入编辑视图选择jpa和mysql

• 就会自动引入依赖

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>

 　　2.2　　配置application.properties

server.port=8088

spring.jpa.show-sql=true

spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/db_boot
spring.datasource.username=root
spring.datasource.password=

spring.jpa.generate-ddl=true

• spring.jpa.generate-ddl=true一定要加

 　　2.3　　编写实体

package com.shyroke.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="t_book")
public class Book {

@Id
@GeneratedValue
private Integer id;

@Column(length=100)
private String bookName;

public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getBookName() {
return bookName;
}
public void setBookName(String bookName) {
this.bookName = bookName;
}

}

 　　2.4　　运行HelloWorldApplication

package com.shyroke;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class HelloWorldApplication {

public static void main(String[] args) {
SpringApplication.run(HelloWorldApplication.class, args);
}
}

• 数据库中自动生成表