JPA

一、依赖：

 

<dependencies>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-data-jpa</artifactId>

    </dependency>

    <dependency>

        <groupId>org.springframework.boot</groupId>

        <artifactId>spring-boot-starter-jdbc</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>

</dependencies>

 

 

二、application.properties配置：

 

spring.datasource.username:root

spring.datasource.password:root

spring.darasource.url: jdbc:mysql://127.0.0.1:3306/databasename?serverTimezone=GMT%2B8

#mysql8.x版本驱动包，要使用以下类作为驱动类，一般都用不到

#spring.darasource.driver-class-name: com.mysql.cj.jdbc.Driver

spring.jpa.hibernate.ddl-auto=update

spring.jpa.show-sql=true

spring.jpa.database-platform=org.hibernate.dialect.MySQL57Dialect

 

 

三、实体类（getset方法和有参无参构造函数都要上）

@Entity //说明 它是和数据表映射的类

@Table(name = "tbl_user") //指定对应映射的表名，省略不写默认表名是类同 user

public class User {

    @Id       //指定主键

    @GeneratedValue(strategy = GenerationType.IDENTITY)

    private Integer id;

    @Column(name = "user_name", length = 5)//与数据表对应的一个字段

    private String username;

    @Column                      //省略不写默认字段名就是属性名

    private String password;

 

四、创建接口UserRepository继承JpaRepository，就会底层实现crud及分页等基本功能

 

public interface UserRepository extends JpaRepository<UserRepository,Integer> {
}

 

五、测试Controller:

 

@RestController

public class UserController {

      @Autowired

      UserRepository userRepository;

      @GetMapping("/user/{id}")

      public User getUserById(@PathVariable("id") Integer id) {

          return userRepository.fifindById(id).get();

}

      @GetMapping("/user")

       public User addUser(User user) {

       return userRepository.save(user);

}

}