SpringBoot integrates JPA

1. Create a new maven project

2. Add the necessary dependencies

    <!--springboot的必须依赖-->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
    </parent>

    <dependencies>
        <!--启动springmvc的相关配置,springboot的自动配置-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--jpa-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>

3. Create a new springboot startup class

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

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

4. Create a new application.properties in the resources and directory

#Create/update the configuration of the data table
spring.jpa.hibernate.ddl-auto=update
#Database address
spring.datasource.url=jdbc:mysql://localhost:3306/qian?useUnicode=true&characterEncoding=utf-8
#database username
spring.datasource.username=root
#Database password
spring.datasource.password=123

• update: Hibernate changes the database according to the given Entity structure.
• create: the database will be created every time and will not be deleted when it is closed
• none: the default setting of mysql, does not change the data structure
• create-drop: Create a database, but delete it every time the sessionFactory is closed

5. Create a new entity class User

At this time, springboot can already be started, but the data table will not be generated, because the jpa of the entity class has not been configured

First create a new user.java

import org.hibernate.annotations.GenericGenerator;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

/**
 * Created by Andy on 2018/1/20.
 */
//表明这是个需要生成数据表的类
@Entity
public class User {
//    定义主键id
    @Id
//    声明一个策略通用生成器，name为”system-uuid”,策略strategy为”uuid”。
    @GenericGenerator(name = "system-uuid", strategy ="uuid")
//    用generator属性指定要使用的策略生成器。
    @GeneratedValue(generator = "system-uuid")
    private String id;
    private String name;
    private Integer age;
    private Boolean sex;

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Boolean getSex() {
        return sex;
    }

    public void setSex(Boolean sex) {
        this.sex = sex;
    }
}

At this time, when the project is started, a user data table will be generated under the specified location.

6. Implement CRUD

CrudRepository is an interface that provides common methods of adding, deleting, modifying, and checking. It is provided internally by spring, and we only need to call it.

@NoRepositoryBean
public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {
    <S extends T> S save(S var1);

    <S extends T> Iterable<S> save(Iterable<S> var1);

    T findOne(ID var1);

    boolean exists(ID var1);

    Iterable<T> findAll();

    Iterable<T> findAll(Iterable<ID> var1);

    long count();

    void delete(ID var1);

    void delete(T var1);

    void delete(Iterable<? extends T> var1);

    void deleteAll();
}

New UserRepository.java

public  interface UserRepository extends CrudRepository<User, String> {

}

7. Implement controller control

New UserController.java

@RestController
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @RequestMapping("/add")
    public User add(String name){
        User user = new User();
        user.setName(name);
        return userRepository.save(user);
    }

    @RequestMapping("/list")
    public Iterable<User> list(){
        Iterable<User> all = userRepository.findAll();
        return all;
    }
}