57.SpringBoot学习笔记–SpringData-整合SpringDataJPA
SpringData JPA 简介
参考：
Java Persistence API 2.0 FINAL 官方文档.pdf
整合 SpringData JPA
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>demo.yangxu</groupId>
<artifactId>springboot-05-data-jpa</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot-05-data-jpa</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</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>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
JPA: ORM（Object Relational Mapping）
1、编写一个实体类（Bean）和数据表进行映射，并且配置好映射关系
demo.yangxu.springboot.entity.User
package demo.yangxu.springboot.entity;
import javax.persistence.*;
//使用JPA注解配置映射关系
@Entity //告诉JPA这是一个实体类（和数据表映射的类）
@Table(name = "tbl_user") //@Table来指定和哪个数据表对应;如果省略默认表名就是user；
public class User {
@Id //这是一个主键
@GeneratedValue(strategy = GenerationType.IDENTITY) //自增主键
private Integer id;
@Column(name = "last_name",length = 50) //这是和数据表对应的一个列
private String lastName;
@Column //省略默认列名就是属性名
private String email;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
}
2、编写一个 Dao 接口来操作实体类对应的数据表（Repository）
demo.yangxu.springboot.repository.UserRepository
package demo.yangxu.springboot.repository;
import demo.yangxu.springboot.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
//继承JpaRepository来完成对数据库的操作
public interface UserRepository extends JpaRepository<User,Integer> {
}
3、基本的配置 JpaProperties
application.yml
spring:
datasource:
url: jdbc:mysql://192.168.25.157/jpa
username: root
password: root
driver-class-name: com.mysql.cj.jdbc.Driver
jpa:
hibernate:
# 更新或者创建数据表结构
ddl-auto: update
# 控制台显示SQL
show-sql: true
4、编写 Controller 进行测试
demo.yangxu.springboot.controller.UserController
package demo.yangxu.springboot.controller;
import demo.yangxu.springboot.entity.User;
import demo.yangxu.springboot.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class UserController {
@Autowired
UserRepository userRepository;
@GetMapping("/user/{id}")
public User getUserById(@PathVariable("id") Integer id){
User user = userRepository.findById(id).orElse(null);
return user;
}
@GetMapping("/user")
public User insertUser(User user){
User save = userRepository.save(user);
return save;
}
}
启动控制台后可以看到自动生成的建表语句：
Hibernate: create table tbl_user (id integer not null auto_increment, email varchar(255), last_name varchar(50), primary key (id)) engine=InnoDB
可以访问以下网址测试：
http://localhost:8080/user?lastName=AA&email=AA@163.com
http://localhost:8080/user/1
