一、@EnableFeignClients详解

1、作用

扫描和注册所有使用注解@FeignClient定义的feign客户端

2、源码

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n5" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public @interface EnableFeignClients {
String[] value() default {};
String[] basePackages() default {};
Class<?>[] basePackageClasses() default {};
Class<?>[] defaultConfiguration() default {};
Class<?>[] clients() default {};</pre>

3、属性说明

属性	说明
String[] value()	包路径。比如 com.sbc.service，会扫描这个包路径下带有 @FeignClient 注解的类并处理
String[] basePackages()
Class<?>[] basePackageClasses()	跟 basePackages 作用一致，basePackages 是个 String 数组，而 basePackageClasses 是个 Class 数组，用于扫描这些类对应的 package
Class<?>[] defaultConfiguration()	默认的配置类，对于所有的 Feign Client，这些配置类里的配置都会对它们生效，可以在配置类里构造 feign.codec.Decoder, feign.codec.Encoder 或 feign.Contract 等bean;
Class<?>[] clients()	注解修饰的类集合，如果指定了该属性，那么扫描功能相关的属性就是失效。比如 value、basePackages 和 basePackageClasses

二、@FeignClient

1、作用

创建声明是API接口，该接口是RESTful风格的。Feign被设计成插拔式的，可注入其他组件和Feign一起使用。默认情况下Feign会和Ribbon相结合进行负载均衡

2、源码

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n30" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public @interface FeignClient {
@AliasFor("name")
String value() default "";
@Deprecated
String serviceId() default "";
String contextId() default "";
@AliasFor("value")
String name() default "";
String qualifier() default "";
String url() default "";
boolean decode404() default false;
Class<?>[] configuration() default {};
Class<?> fallback() default void.class;
Class<?> fallbackFactory() default void.class;
String path() default "";
boolean primary() default true;</pre>

3、属性说明

属性	说明
String value()	提供服务的名称
String path()	请求路径,定义当前Feign客服端统一前缀
String name()	跟 value 属性作用一致
String qualifier()	给 FeignClient 设置 @Qualifier 注解
String url()	手动调用url地址,一般用于测试，用于替换服务名。优先级比服务名高。
boolean decode404()	默认是 false，表示对于一个 http status code 为 404 的请求是否需要进行 decode，默认不进行 decode，当成一个异常处理。设置为true之后，遇到 404 的 response 还是会解析 body
Class<?>[] configuration()	对于单个 FeignClient 的配置，而 @EnableFeignClients 里的 defaultConfiguration 属性是作用域全局的，针对所有的 FeignClient
Class<?> fallback()	表示 fallback 类，需要实现 FeignClient 对应的接口，当调用方法发生异常的时候会调用这个 Fallback 类对应的 FeignClient 接口方法
Class<?> fallbackFactory()	表示生产 fallback 类的 Factory，可以实现 feign.hystrix.FallbackFactory 接口，FallbackFactory 内部会针对一个 Throwable 异常返回一个 Fallback 类进行 fallback 操作 ，用于封装通用的容错逻辑,减少重复代码
boolean primary()	默认是 true，表示当前这个 FeignClient 生成的 bean 是否是 primary。

个人建议 编码器，解码器，重试器，调用解析器一般使用默认的就行

三、自定义配置

1、说明

在实际开发中有可能Feign默认配置不能满足需求，这时就需要自定义Feign配置。

按着配置方式来来划分:

• java代码配置

• 配置文件配置

按照作用来说又可以分为:

• 全局配置

• 局部配置(针对单个Feign接口)

配置文件配置格式如下:

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="yml" cid="n83" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">feign:
client:

修改默认配置的名称 默认名default

default-config: default
config:

feign的名称

feign-name:

连接超时时间

connection-timeout: 1000

读取超时时间

read-timeout: 5000

日志配置级别

logger-level: full

错误解码器

error-decoder: com.xxx

重试机制

retryer: feign.Default

自定义拦截器

request-interceptors:

decoder:
encoder:

Spring MVC 注解支持

contract:</pre>

FeignClientConfiguration配置类信息

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n85" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public static class FeignClientConfiguration {
//. 日志级别
private Logger.Level loggerLevel;
//连接超时时间 java.net.HttpURLConnection#getConnectTimeout()，如果使用Hystrix，该配置无效
private Integer connectTimeout;
//读取超时时间 java.net.HttpURLConnection#getReadTimeout()，如果使用Hystrix，该配置无效
private Integer readTimeout;
//重试接口实现类，默认实现 feign.Retryer.Default
private Class<Retryer> retryer;
// 错误编码
private Class<ErrorDecoder> errorDecoder;
// 请求拦截器
private List<Class<RequestInterceptor>> requestInterceptors;
//是否开启404编码
private Boolean decode404;
}</pre>

核心配置

默认的请求connectionTimeout为10s,readTimeout为60s

Java Config配置

全局配置

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n90" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">@SpringBootApplication
@EnableFeignClients(defaultConfiguration = FeignClientsConfiguration.class)
public class NetflixFeignClientApplication {
public static void main(String[] args) {
SpringApplication.run(NetflixFeignClientApplication.class, args);
}
}</pre>

局部配置

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="java" cid="n92" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">@Configuration
public class FeignCustomConfiguration {
}
​
@FeignClient(configuration= FeignCustomConfiguration.class)
public interface FeignUserService {
}</pre>

四、网络请求配置

1、httpclient配置

1、添加依赖

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="xml" cid="n97" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-httpclient</artifactId>
</dependency></pre>

2、配置信息

<pre spellcheck="false" class="md-fences md-end-block ty-contain-cm modeLoaded" lang="yml" cid="n99" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: normal; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">feign:
httpclient:

让feign使用apache httpclient作请求

enabled: true

feign的最大连接数

max-connections: 200

feign单个路径的最大连接数

max-connections-per-route: 50</pre>

2、OkHttp(推荐)

1、添加依赖

<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="xml" cid="n102" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;"><dependency>
<groupId>io.github.openfeign</groupId>
<artifactId>feign-okhttp</artifactId>
</dependency></pre>

2、配置信息

<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="java" cid="n104" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">feign:
httpclient:
enabled: false
okhttp:
enabled: true</pre>

四、Gzip压缩

1、说明

Spring Cloud Feign支持请求和响应Gzip压缩，提供传输效率。只需要在配置文件配置即可

2、配置信息

<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="yml" cid="n109" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">feign:
client:
config:
# 默认全局配置 默认配置名称 default
default:
compression:
request:
# 配置请求支持GZIP压缩，默认为false
enable: true
#配置压缩支持的Mime Type
mime-types: application/json
# 配置压缩数据大小的上下限
min-request-size: 2048
reponse:
#配置响应支持GZIP压缩，默认为false
enable: true</pre>

1、Date类型参数的时差

<pre spellcheck="false" class="md-fences mock-cm md-end-block" lang="java" cid="n111" mdtype="fences" style="box-sizing: border-box; overflow: visible; font-family: Monaco, Consolas, "Andale Mono", "DejaVu Sans Mono", monospace; margin-top: 0px; margin-bottom: 20px; font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; white-space: pre-wrap; background: rgb(51, 51, 51); position: relative !important; padding: 10px 10px 10px 30px; width: inherit; color: rgb(184, 191, 198); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">@Component
public class DateFormatRegister implements FeignFormatterRegistrar{

public DateFormatRegister(){
}

@Override
public void registerFormatters(FormatterRegistry registry) {
registry.addConverter(Date.class, String.class, new Date2StringConverter());
}

private class Date2StringConverter implements Converter<Date,String>{

@Override
public String convert(Date source) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return sdf.format(source);
}

}
}</pre>

参考

https://blog.csdn.net/andy_zhang2007/article/details/86680622#_2