Getting Started

引导设置一个工作环境的简单方法是通过 start.spring.io 创建一个基于 Spring 的项目，或者在 Spring Tools 中创建一个 Spring 项目。

An easy way to bootstrap setting up a working environment is to create a Spring-based project via start.spring.io or create a Spring project in Spring Tools.

Examples Repository

GitHub spring-data-examples repository 托管了多个示例，您可以下载和试用它们来了解库的工作原理。

The GitHub spring-data-examples repository hosts several examples that you can download and play around with to get a feel for how the library works.

Hello World

让我们从一个简单的实体及其对应的存储库开始：

Let’s start with a simple entity and its corresponding repository:

@Entity
class Person {

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

  // getters and setters omitted for brevity
}

interface PersonRepository extends Repository<Person, Long> {

  Person save(Person person);

  Optional<Person> findById(long id);
}

创建要运行的主应用程序，如下所示：

Create the main application to run, as the following example shows:

@SpringBootApplication
public class DemoApplication {

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

  @Bean
  CommandLineRunner runner(PersonRepository repository) {
    return args -> {

      Person person = new Person();
      person.setName("John");

      repository.save(person);
      Person saved = repository.findById(person.getId()).orElseThrow(NoSuchElementException::new);
    };
  }
}

即使在这么简单的例子中，也有一些值得注意的事情：

Even in this simple example, there are a few notable things to point out:

Repository instances are automatically implemented. When used as parameters of @Bean methods, these will be autowired without further need for annotations.
The basic repository extends Repository. We suggest to consider how much API surface you want to expose towards your application. More complex repository interfaces are ListCrudRepository or JpaRepository.