什么是Feign？
Feign是一个声明式Web服务客户端。支持可插拔编码器和解码器。Spring Cloud的Feign添加了对Spring MVC注释的支持，并且使用了Spring Web中默认使用的相同HttpMessageConverters。Spring Cloud的Feign将Ribbon和Eureka集成在一起，在使用Feign时提供负载均衡的http客户端。
快速开始
这个案例依赖Eureka-Server,请准备好server服务。Eureka相关查看Spring-Cloud系列(一) Eureka
添加依赖
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.13.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
<spring-cloud.version>Dalston.SR5</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-feign</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
代码
注解扫描
@EnableEurekaClient
@EnableFeignClients
@SpringBootApplication
public class FeignApplication {
public static void main(String[] args) {
SpringApplication.run(FeignApplication.class, args);
}
}
定义客户端
@FeignClient("eureka-client-one") //必须是你调用服务的名称,即spring.application.name
public interface FeignTestClient {
/**
* Feign默认解析合约是Spring-MVC的注解
* @return
*/
@RequestMapping(method = RequestMethod.GET, value = "/url")
String getUrl();
}
使用
@Autowired
private FeignTestClient feignTestClient;
@GetMapping("/test")
public String testService(){
return feignTestClient.getUrl();
}
application配置
server:
</br> port: 8083
</br>spring:
</br> application:
</br> name: feign-one
</br>eureka:
</br> instance:
</br> prefer-ip-address: true
</br> instanceId: ${spring.application.name}:${vcap.application.instance_id:${spring.application.instance_id:${random.value}}}
</br> client:
</br> serviceUrl:
</br> defaultZone: http://user:Pass123456@localhost:8761/eureka
启动效果
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自定义feignClient和feign日志登等级
配置定义客户端
自定义配置
@Configuration
public class FeignConfiguration {
@Bean
public Contract feignContract() {
return new feign.Contract.Default();
}
}
定义客户端
@FeignClient(name = "eureka-client-one",configuration = FeignConfiguration.class)
public interface FeignTestClient {
@RequestLine("GET /url") //根据配置现在Feign支持的是原生注解
String getUrl();
}
注意！Feign的客户端的自定义和Ribbon类似，配置类不能放在启动类的平级和子目录下。否则会覆盖全局配置，正确目录如下:</br>
代码定义客户端
定义客户端
public interface FeignTestClient {
@RequestLine("GET /url")
String getUrl();
}
使用客户端
@RestController
@Import(FeignClientsConfiguration.class)
public class FeignTestContoller {
@GetMapping("/test")
public String testService(){
FeignTestClient feignTestClient = Feign.builder()
.options(new Request.Options(1000, 3500))
.retryer(new Retryer.Default(5000, 5000, 3))
.requestInterceptor(new BasicAuthRequestInterceptor("user", "Pass123456"))
.target(FeignTestClient.class, "http://lodalhost:8080");
return feignTestClient.getUrl();
}
}
Feign提供的配置
Feign提供以下默认配置：
- Decoder feignDecoder: ResponseEntityDecoder (which wraps a SpringDecoder)
- Encoder feignEncoder: SpringEncoder
- Logger feignLogger: Slf4jLogger
- Contract feignContract: SpringMvcContract
- Feign.Builder feignBuilder: HystrixFeign.Builder
- Client feignClient: if Ribbon is enabled it is a LoadBalancerFeignClient, otherwise the default feign client is used.
Feign未提供默认配置：
- Logger.Level
- Retryer
- ErrorDecoder
- Request.Options
- Collection<RequestInterceptor>
- SetterFactory
自定义日志级别
application配置
logging:
</br> level:
</br> com.midai.feign.client.FeignTestClient: DEBUG #Client是用户自定义Clien全称
代码配置
@Configuration
public class FeignConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
Feign的可选日志等级
- NONE, No logging (DEFAULT).
- BASIC, Log only the request method and URL and the response status code and execution time.
- HEADERS, Log the basic information along with request and response headers.
- FULL, Log the headers, body, and metadata for both requests and responses.
Feign其他用法和配置
抽取公用包依赖
UserService.java
public interface UserService {
@RequestMapping(method = RequestMethod.GET, value ="/users/{id}")
User getUser(@PathVariable("id") long id);
}
UserResource.java
@RestController
public class UserResource implements UserService {
}
UserClient.java
@FeignClient("users")
public interface UserClient extends UserService {
}
接口抽取共用，服务提供方直接实现,FeignClient继承提高代码可用性。
Feign请求响应设置
Feign请求响应压缩
feign:
</br> compression:
</br> request:
</br> enabled： true
</br>feign:
</br> compression:
</br> response:
</br> enabled: true
Feign请求设置
feign:
</br> compression:
</br> request:
</br> mime-types: text/xml,application/xml,application/json
</br>feign:
</br> compression:
</br> request:
</br> min-request-size: 2048
