前言

在开发SpringCloud应用中，Feign作为声明式调用的事实标准极大的简化了Rest远程调用，提供了类本地化的调用方式。服务提供方的接口暴露方式是通过Controller暴露Restful，而在这个Controller的代码现实中大部分都是处理请求然后再调用Service中的方法，是一个比较模板化的功能，但是工作量确不少。本文介绍一种通过动态代理的方式无需Controller直接暴露Restful接口。
本文中使用笔者在Github开源的框架来实现，本文的讲解也在这个框架基础之上来说明
Git路径：https://github.com/leecho/spr...

依赖

     <dependency><groupId>com.github.leecho</groupId><artifactId>spring-cloud-starter-feign-proxy</artifactId><version>{last-version}</version></dependency>

实现

定义Service Interface

首先定义服务接口，使用@FeignClient标示是一个Feign接口，在这个示例Sevice中定义了CURD和文件上传方法，并使用了一些常用参数注解

@Api(tags = "DemoService", description = "Demo Feign Client")
@FeignClient("demo-service")
public interface DemoService {/*** create demo** @param demo* @return*/@ApiOperation(value = "Create demo")@PostMapping(value = "/demo")Demo create(@RequestBody @Valid @ApiParam Demo demo);/*** update demo** @param demo* @return*/@PutMapping(value = "/demo")Demo update(@RequestBody @Valid Demo demo);/*** delete demo** @param id* @return*/@DeleteMapping(value = "/demo/{id}")Demo delete(@PathVariable(name = "id") String id);/*** list demo** @param id* @param headerValue test header value* @return*/@GetMapping(value = "/demo/{id}")Demo get(@PathVariable(name = "id") String id, @RequestHeader(name = "header") String headerValue);/*** list demos** @return*/@GetMapping(value = "/demos")List<Demo> list();/*** upload file** @param file* @return*/@PostMapping(value = "/demo/upload")String upload(@RequestPart(name = "file") MultipartFile file);
}

实现Service

在实现类中简单的实现了CURD和上传文件的方法

@Slf4j
@Primary
@Service
public class DemoServiceImpl implements DemoService {@Overridepublic Demo create(Demo demo) {log.info("Create executed : " + demo);return demo;}@Overridepublic Demo update(Demo demo) {log.info("Update execute :" + demo);return demo;}@Overridepublic Demo delete(String id) {log.info("Delete execute : " + id);return Demo.builder().name("demo-" + id).data("data-" + id).build();}@Overridepublic Demo get(String id, String header) {Demo demo = Demo.builder().name(header).data(header).build();System.out.println("Get execute : " + id + "," + header);return demo;}@Overridepublic List<Demo> list() {System.out.println("List execute");List<Demo> demos = new ArrayList<>();for (int i = 0; i < 5; i++) {Demo demo = Demo.builder().name("demo-" + i).data("data" + i).build();demos.add(demo);}return demos;}@Overridepublic String upload(MultipartFile file) {return file.getOriginalFilename();}
}

动态生成Restful接口的原理是动态生成Controller类实现ServiceInterface，如果真正的实现类会被其他BEAN依赖，需要通过注解@Primary来方式来防止依赖冲突

配置应用

在应用中通过@EnableFeignProxies来标示应用在启动的过程中会扫描所有的FeignClients并暴露Restful接口

@EnableFeignProxies(basePackages = "com.github.leecho")
@ComponentScan("com.github.leecho")
@SpringBootApplication
public class DemoApplication {public static void main(String[] args) {SpringApplication.run(DemoApplication.class, args);}}

测试用例

在测试用例中对Service的接口进行测试

@SpringBootTest
@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
public class DemoApplicationTest {@Autowiredprivate WebApplicationContext context;private MockMvc mvc;@Beforepublic void setUp() {mvc = MockMvcBuilders.webAppContextSetup(context).build();}@Testpublic void create() throws Exception {mvc.perform(MockMvcRequestBuilders.post("/demo").contentType(MediaType.APPLICATION_JSON_UTF8).content(new ObjectMapper().writeValueAsString(Demo.builder().name("create").data("data").build())).accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}@Testpublic void update() throws Exception {mvc.perform(MockMvcRequestBuilders.put("/demo").contentType(MediaType.APPLICATION_JSON_UTF8).content(new ObjectMapper().writeValueAsString(Demo.builder().name("update").data("data").build())).accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}@Testpublic void delete() throws Exception {mvc.perform(MockMvcRequestBuilders.delete("/demo/{id}", "1").contentType(MediaType.APPLICATION_JSON_UTF8).accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}@Testpublic void get() throws Exception {mvc.perform(MockMvcRequestBuilders.get("/demo/{id}", "1").contentType(MediaType.APPLICATION_JSON_UTF8).header("header", "header-value").accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}@Testpublic void list() throws Exception {mvc.perform(MockMvcRequestBuilders.get("/demos").contentType(MediaType.APPLICATION_JSON_UTF8).accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}@Testpublic void upload() throws Exception {mvc.perform(MockMvcRequestBuilders.multipart("/demo/upload").file(new MockMultipartFile("file", "test.txt", ",multipart/form-data", "upload test".getBytes())).accept(MediaType.APPLICATION_JSON)).andExpect(MockMvcResultMatchers.status().isOk()).andDo(MockMvcResultHandlers.print());}
}

在启动日志中也可以看到Restful接口已经暴露成功。

后语

关于这个框架的介绍，后续详细的给大家进行介绍。文中所涉及到的代码也在Git中：spring-cloud-feign-proxy-sample