前言：最近项目中经常用到Feign进行服务端之前的调用，因此小小总结一下
1. Feign介绍
Feign是Netflix公司开源的轻量级rest客户端，使用Feign可以非常方便的实现Http 客户端。Spring Cloud引入Feign并且集成了Ribbon实现客户端负载均衡调用。
2. pom.xml
不写入版本号的话会引入和springboot版本号相匹配的版本
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
3. 启动类加入注解 @EnableFeignClients
@SpringBootApplication
@EnableFeignClients // Feign注解
public class TestApplication {
public static void main(String[] args) {
SpringApplication.run(TestApplication.class, args);
}
}
4. 添加Feign配置文件(如果不添加此配置文件会报如下错误)
错误信息： No qualifying bean of type ‘org.springframework.boot.autoconfigure.http.HttpMessag
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.converter.HttpMessageConverter;
import java.util.stream.Collectors;
/**
* feign的http客户端配置
*/
@Configuration
public class FeignConfig {
/**
*No qualifying bean of type ‘org.springframework.boot.autoconfigure.http.HttpMessage
*/
@Bean
@ConditionalOnMissingBean
public HttpMessageConverters messageConverters(ObjectProvider<HttpMessageConverter<?>> converters) {
return new HttpMessageConverters(converters.orderedStream().collect(Collectors.toList()));
}
}
5. 如果需要传递header参数，需要下述配置文件
bootstrap.yml 增加配置
- 设置hystrix的隔离策略
hystrix.command.default.execution.isolation.strategy = SEMAPHORE
import feign.Logger;
import feign.RequestInterceptor;
import feign.RequestTemplate;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* feign的header配置
*/
@Configuration
public class FeignHeaderConfig {
//feign请求转发是需要从原请求头复制的header信息
final String[] copyHeaders = new String[]{"cookie"};
/**
* 重写后feign转发请求会携带原请求的Head信息
*/
private class FeignBasicAuthRequestInterceptor implements RequestInterceptor {
@Override
public void apply(RequestTemplate requestTemplate) {
// SystemConstant.COOKIE="Cookie"
// new DefaultTokenHandler().getTokenInCookie() 为获取到的Cookie信息
/**
spring-boot-starter-webflux 框架走下述方法
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
*/
requestTemplate.header(SystemConstant.COOKIE, new DefaultTokenHandler().getTokenInCookie());
/**
spring-boot-starter-web 框架走下面注释方法
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
*/
/*
ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder
.getRequestAttributes();
if (attributes != null) {
HttpServletRequest request = attributes.getRequest();
Enumeration<String> headerNames = request.getHeaderNames();
if (headerNames != null) {
while (headerNames.hasMoreElements()) {
String name = headerNames.nextElement();
String values = request.getHeader(name);
if (iscopy(name)) {
requestTemplate.header(name, values);
}
}
}
}
*/
}
}
/**
* @param name
* @return
*/
private Boolean iscopy(String name) {
for (String header : copyHeaders) {
if (header.equals(name)) {
return true;
}
}
return false;
}
/**
* feign请求拦截器
*
* @return
*/
@Bean
public RequestInterceptor requestInterceptor() {
return new FeignBasicAuthRequestInterceptor();
}
/**
* 开启feign调用日志打印的debug模式
*
* @return
*/
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
6. 在Feign客户端中配置
- FeignTest.class 客户端调用类
/**
* 发布用户信息查询相关的接口
*/
@FeignClient(value = "base", configuration = FeignHeaderConfig.class, contextId = "FeignTest", fallbackFactory = FeignTestFactory.class)
public interface FeignTest {
/**
* 增量更新用户信息
*
* @param info
*/
@PostMapping("user")
public BaseResponse user(@RequestBody Info info);
}
- FeignTestFactory.class 异常处理的工厂类
/**
* 异常处理的工厂类
*/
@Component
public class FeignTestFactory<T> implements FallbackFactory<T>, LoggerBase {
@Override
public T create(Throwable cause) {
if (cause.getMessage() != null)
error("feign接口调用异常,{}", cause.getMessage());
return (T) new TestFallBackImp(cause.getMessage());
}
}
- TestFallBackImp.class 服务降级处理类
/**
* 服务降级处理类
*/
public class TestFallBackImp implements FeignTest {
String errMsg;
public TestFallBackImp(String errMsg) {
this.errMsg = errMsg;
}
@Override
public BaseResponse user(Info info) {
return new BaseResponse().err(errMsg);
}
}
至此，Feign已经配置好了
其他错误
- The bean 'XXX.FeignClientSpecification', defined in null, could not be registered
原因：2.1.0以上版本的，将不再默认支持 FeignClient 的name属性 的相同名字。
即 ：多个接口上的@FeignClient(“相同服务名”)会报错，overriding is disabled(覆盖 是 禁止的/关闭的)。
可以添加配置
spring.main.allow-bean-definition-overriding=true
阅读源码后，发现也可以把contextId设置成不一样的
