<!--JPA数据库持久化-->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;


@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class Customer {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    private String firstName;
    private String lastName;

    public Customer(String firstName, String lastName){
        this.firstName = firstName;
        this.lastName = lastName;
    }

}

import java.util.List;

import org.springframework.data.repository.CrudRepository;

public interface CustomerRepository extends CrudRepository<Customer, Long> {

    List<Customer> findByLastName(String lastName);

    Customer findById(long id);
}

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;

import java.io.IOException;


@SpringBootApplication
public class DemoApplication {

    private static final Logger log = LoggerFactory.getLogger(DemoApplication.class);


    public static void main(String[] args) throws IOException {

        SpringApplication.run(DemoApplication.class, args);
	}




    @Bean
    public CommandLineRunner demo(CustomerRepository repository) {
        return (args) -> {
            // save a few customers
            repository.save(new Customer("Jack", "Bauer"));
            repository.save(new Customer("Chloe", "O'Brian"));
            repository.save(new Customer("Kim", "Bauer"));
            repository.save(new Customer("David", "Palmer"));
            repository.save(new Customer("Michelle", "Dessler"));

            // fetch all customers
            log.info("Customers found with findAll():");
            log.info("-------------------------------");
            for (Customer customer : repository.findAll()) {
                log.info(customer.toString());
            }
            log.info("");

            // fetch an individual customer by ID
            Customer customer = repository.findById(1L);
            log.info("Customer found with findById(1L):");
            log.info("--------------------------------");
            log.info(customer.toString());
            log.info("");

            // fetch customers by last name
            log.info("Customer found with findByLastName('Bauer'):");
            log.info("--------------------------------------------");
            repository.findByLastName("Bauer").forEach(bauer -> {
                log.info(bauer.toString());
            });
            // for (Customer bauer : repository.findByLastName("Bauer")) {
            // 	log.info(bauer.toString());
            // }
            log.info("");
        };
    }
}