Tiven Wang
Wang Tiven July 25, 2017
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Oryx on top of a dune in the NamibRand Nature Reserve, Namibia.

下載本文完整項目代碼 Github

本文在 Spring Boot 構建項目基礎上進行的,如果讀者想要了解 Spring Boot 項目如何創建請參考Try Cloud Foundry 7 - Spring Boot

Spring Web

Setup Spring Web

如果你的Spring Boot項目裡還沒有添加Spring Web依賴,可以添加如下組件:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Build Restful API

使用 @RestController @RequestMapping 可以编写我们的 Restful API。

@RestController
@RequestMapping("/hero")
public class HeroController {

  @Autowired(required = false) HeroRepository heroRepository;

  @RequestMapping("")
  Iterable<Hero> getAll() {
      return heroRepository.findAll();
  }

  @RequestMapping(path="", method=RequestMethod.POST)
  Hero create(@RequestBody Hero hero) {
      return heroRepository.save(hero);
  }

  @RequestMapping("/{id}")
  Hero get(@PathVariable BigInteger id) {
      return heroRepository.findOne(id);
  }

  @RequestMapping(path="/{id}", method=RequestMethod.DELETE)
  void delete(@PathVariable BigInteger id) {
      heroRepository.delete(id);
  }
}

啟動應用程序可訪問鏈接 http://127.0.0.1:8080/hero

Spring Data Commons

如果你的項目使用了 Spring Data framework 的話,參考文檔Spring Data Commons - Reference Documentation - 3.8.2. Web support 配置對 Web 的支持。

如果是註解的方式可以如下配置:

@Configuration
@EnableWebMvc
@EnableSpringDataWebSupport
class WebConfiguration { }

@EnableSpringDataWebSupport 註解會啟動對Restful API的特性的支持。

如果使用了 Spring Boot @EnableAutoConfiguration 自動發現配置功能(@SpringBootApplication包含了@EnableAutoConfiguration),則不需要@EnableSpringDataWebSupport,Spring Boot會自動查找到 SpringDataWebConfiguration 並進行正確的配置。

如果你仍然在使用xml配置方式:

<bean class="org.springframework.data.web.config.SpringDataWebConfiguration" />

<!-- If you're using Spring HATEOAS as well register this one *instead* of the former -->
<bean class="org.springframework.data.web.config.HateoasAwareSpringDataWebConfiguration" />

以上方式中的 Spring HATEOAS 都是在你把 Spring HATEOAS 組件加入項目依賴中自動發現配置的。

Paging and Sorting

把Crud換成PagingAndSortingRepository

public interface HeroRepository extends PagingAndSortingRepository<Hero, BigInteger> {
}

然後 RestController 的 query method 加上參數 Pageable pageable:

@RequestMapping("")
Page<Hero> getAll(Pageable pageable) {
    return heroRepository.findAll(pageable);
}

最終在查詢時使用的參數格式為: http://127.0.0.1:8080/hero?size=2&page=1&sort=name,desc

Spring Data Rest

Spring 提供了更为简便的方式创建 Restful APIs , Spring Data REST is part of the umbrella Spring Data project and makes it easy to build hypermedia-driven REST web services on top of Spring Data repositories.

Basics

Spring data rest configuration with Maven:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>

為 Hero Repository 添加註解 @RepositoryRestResource(collectionResourceRel = "heros", path = "heros"),為了與@RestController說明的 Restful api 區分這裡使用heros作為路徑。

@RepositoryRestResource(collectionResourceRel = "heros", path = "/heros")
public interface HeroRepository  extends CrudRepository<Hero, BigInteger> {
}

啟動應用 mvn spring-boot:run 則可以看到 hero 的 restful apis :

http://127.0.0.1:8080/heros

Spring Data REST uses the HAL format for JSON output. It is flexible and offers a convenient way to supply links adjacent to the data that is served.

More

你的 HeroRespository 也可以继承 PagingAndSortingRepository 或者 MongoRepository之类的,可以提供更为丰富的 Restful 功能。

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