基于Eureka的远程调用 - Feign Client
基于Eureka的远程调用 - Feign Client
在前面的文章中，我们构建了基于Eureka的RPC，但是获取地址，发起调用，对象转换都是手动完成。本文介绍Spring Cloud体系中专注完成RPC的Feign Client，大大简化PRC使用
本文是在Eureka快速体验基础上构建的，但是如果eureka已经连接好，可以不用关注
添加依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
<version>2.1.1.RELEASE</version>
</dependency>spring-cloud-starter-feign已经停止更新了，请使用spring-cloud-starter-openfeign
定义远程调用接口
- 调用方
HomeRemoteClient
//values是服务提供方在eureka注册的名字，path是该接口中所有请求url的前缀
@FeignClient(value = "tenmao-eureka-provider", path = "/home")
public interface HomeRemoteClient {
//支持无参数调用
@GetMapping("ping")
String ping();
//支持路径参数，URL参数， header以及body
//支持对返回值自动进行HttpMessageConverter
@PutMapping("/{personId}")
WebResult<String> updatePerson(@PathVariable("personId") int personId, @RequestParam("hobby") String hobby, @RequestHeader("Session-Id") String sessionId, @RequestBody Person person);
}- 对应的服务提供方
HomeController在另外一个进程，该进程注册到eureka的名字是tenmao-eureka-provider，与服务调用方中value一致
@Slf4j
@RestController
@RequestMapping("home")
public class HomeController {
@GetMapping("ping")
public String ping() {
return "success";
}
@PutMapping("/{personId:\\d+}")
public WebResult<String> update(@PathVariable int personId, @RequestParam String hobby, @RequestHeader("Session-Id") String sessionId, @RequestBody Person person) {
if (person.getId() != personId) {
return new WebResult<>(400, "id should be the same");
}
log.info("{}", person);
log.info("sessionId: {}", sessionId);
return new WebResult<>(hobby);
}
}使用
@EnableFeignClients
@SpringBootApplication
@EnableEurekaClient
public class EurekaClientApplication {
@Resource
private HomeRemoteClient homeRemoteClient;
public static void main(String[] args) {
SpringApplication.run(EurekaClientApplication.class, args);
}
@Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
return args -> {
String result = homeRemoteClient.ping();
System.out.println(result);
Person tenmao = new Person(100, "tenmao", 20, true);
WebResult<String> webResult = homeRemoteClient.updatePerson(100, "basketball", UUID.randomUUID().toString(), tenmao);
System.out.println(webResult);
};
}
}一些高级配置
详细日志
- 配置类
@Configuration
public class FeignConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
//这里记录所有，根据实际情况选择合适的日志level
return Logger.Level.FULL;
}
}
- 使用上述配置类
```java@FeignClient(value = "tenmao-eureka-provider", configuration = FeignConfiguration.class, path = "/home")
public interface HomeRemoteClient {
@GetMapping("ping")String ping();@PutMapping("/{personId}")WebResult<String> updatePerson(@PathVariable("personId") int personId, @RequestParam("hobby") String hobby, @RequestHeader("Session-Id") String sessionId, @RequestBody Person person);}
- 启动配置(`application.properties`)
```javascriptlogging.level.com.tenmao.eurekaclient.remote=debug
- 日志内容
```javascriptHomeRemoteClient#updatePerson ---> PUT http://tenmao-eureka-provider/home/100?hobby=basketball HTTP/1.1
HomeRemoteClient#updatePerson Session-Id: 34155859-1b70-4104-b17a-b41d4b0010f2
HomeRemoteClient#updatePerson Content-Type: application/json;charset=UTF-8
HomeRemoteClient#updatePerson Content-Length: 87
HomeRemoteClient#updatePerson
HomeRemoteClient#updatePerson {"id":100,"name":"tenmao","age":20,"gender":true,"birthTime":"2019-04-18T18:04:35.915"}
HomeRemoteClient#updatePerson ---> END HTTP (87-byte body)
HomeRemoteClient#updatePerson <--- HTTP/1.1 200 (11ms)
HomeRemoteClient#updatePerson content-type: application/json;charset=UTF-8
HomeRemoteClient#updatePerson date: Thu, 18 Apr 2019 10:07:36 GMT
HomeRemoteClient#updatePerson transfer-encoding: chunked
HomeRemoteClient#updatePerson
HomeRemoteClient#updatePerson {"code":200,"msg":"success","data":"basketball"}
HomeRemoteClient#updatePerson <--- END HTTP (48-byte body)
> 日志显示了非常详细的HTTP协议内容
>
### 自定义HttpMessageConverter
```javascript@Slf4j
@Configuration
public class FeignConfiguration {
private static final Gson GSON;static { final GsonBuilder gsonBuilder = new GsonBuilder(); final DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss"); final DateTimeFormatter dateFmt = DateTimeFormatter.ofPattern("yyyy/MM/dd"); gsonBuilder.registerTypeAdapter(LocalDateTime.class, (JsonSerializer<LocalDateTime>) (localDateTime, type, jsonSerializationContext) -> new JsonPrimitive(localDateTime.format(fmt))); gsonBuilder.registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (jsonElement, type, jsonDeserializationContext) -> { log.info("", jsonElement.getAsString()); return LocalDateTime.parse(jsonElement.getAsString(), fmt); }); gsonBuilder.registerTypeAdapter(LocalDate.class, (JsonSerializer<LocalDate>) (localDate, type, jsonSerializationContext) -> new JsonPrimitive(localDate.format(dateFmt))); gsonBuilder.registerTypeAdapter(LocalDate.class, (JsonDeserializer<LocalDate>) (jsonElement, type, jsonDeserializationContext) -> LocalDate.parse(jsonElement.getAsString(), dateFmt)); gsonBuilder.serializeNulls(); GSON = gsonBuilder.create();}@Beanpublic Encoder feignEncoder(){ HttpMessageConverter jacksonConverter = new GsonHttpMessageConverter(GSON); ObjectFactory<HttpMessageConverters> objectFactory = () -> new HttpMessageConverters(jacksonConverter); return new SpringEncoder(objectFactory);}@Beanpublic Decoder feignDecoder() { HttpMessageConverter jacksonConverter = new GsonHttpMessageConverter(GSON); ObjectFactory<HttpMessageConverters> objectFactory = () -> new HttpMessageConverters(jacksonConverter); return new ResponseEntityDecoder(new SpringDecoder(objectFactory));}@BeanLogger.Level feignLoggerLevel() { //这里记录所有，根据实际情况选择合适的日志level return Logger.Level.FULL;}}