Spring Cloud OpenFeign Features
Declarative REST Client: Feign
Feign是一种声明性 Web 服务客户端,它让编写 Web 服务客户端变得更加容易。要使用 Feign,请创建一个界面并对其进行注释。它具有可插拔的注释支持,包括 Feign 注释和 JAX-RS 注释。Feign 还支持可插拔的编码器和解码器。Spring Cloud 为 Spring MVC 注释增加了支持,并用于 Spring Web 中默认使用的相同 HttpMessageConverters
。当使用 Feign 时,Spring Cloud 集成了 Eureka、Spring Cloud CircuitBreaker 以及 Spring Cloud LoadBalancer,以提供负载均衡的 http 客户端。
Feign is a declarative web service client.
It makes writing web service clients easier.
To use Feign create an interface and annotate it.
It has pluggable annotation support including Feign annotations and JAX-RS annotations.
Feign also supports pluggable encoders and decoders.
Spring Cloud adds support for Spring MVC annotations and for using the same HttpMessageConverters
used by default in Spring Web.
Spring Cloud integrates Eureka, Spring Cloud CircuitBreaker, as well as Spring Cloud LoadBalancer to provide a load-balanced http client when using Feign.
How to Include Feign
要将 Feign 包含在你的项目中,请使用组 `org.springframework.cloud`和构件 ID `spring-cloud-starter-openfeign`的启动器。有关使用当前 Spring Cloud 发布版本来设置你的构建系统的详细信息,请参阅 Spring Cloud Project page。
To include Feign in your project use the starter with group org.springframework.cloud
and artifact id spring-cloud-starter-openfeign
. See the Spring Cloud Project page
for details on setting up your build system with the current Spring Cloud Release Train.
Spring Boot 应用示例
Example spring boot app
@SpringBootApplication
@EnableFeignClients
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
@FeignClient("stores")
public interface StoreClient {
@RequestMapping(method = RequestMethod.GET, value = "/stores")
List<Store> getStores();
@GetMapping("/stores")
Page<Store> getStores(Pageable pageable);
@PostMapping(value = "/stores/{storeId}", consumes = "application/json")
Store update(@PathVariable("storeId") Long storeId, Store store);
@DeleteMapping("/stores/{storeId:\\d+}")
void delete(@PathVariable Long storeId);
}
在 `@FeignClient`注释中,字符串值(上方的“stores”)是一个任意客户端名称,用于创建一个 Spring Cloud LoadBalancer client。你还可以使用 `url`属性(绝对值或仅主机名)指定一个 URL。应用程序上下文中 Bean 的名称是接口的全限定名称。为了指定你自己的别名字符串,你可以使用 `@FeignClient`注释的 `qualifiers`值。
In the @FeignClient
annotation the String value ("stores" above) is an arbitrary client name, which is used to create a Spring Cloud LoadBalancer client.
You can also specify a URL using the url
attribute
(absolute value or just a hostname). The name of the bean in the
application context is the fully qualified name of the interface.
To specify your own alias value you can use the qualifiers
value
of the @FeignClient
annotation.
上述负载均衡器客户端需要发现“stores”服务的物理地址。如果你的应用程序是 Eureka 客户端,那么它将在 Eureka 服务注册表中解析服务。如果你不想使用 Eureka,则可以使用 SimpleDiscoveryClient
在外部配置中配置服务器列表。
The load-balancer client above will want to discover the physical addresses
for the "stores" service. If your application is a Eureka client then
it will resolve the service in the Eureka service registry. If you
don’t want to use Eureka, you can configure a list of servers
in your external configuration using SimpleDiscoveryClient
.
Spring Cloud OpenFeign 支持 Spring Cloud LoadBalancer 的阻塞模式中可用的所有功能。你可以在 project documentation中阅读更多相关信息。
Spring Cloud OpenFeign supports all the features available for the blocking mode of Spring Cloud LoadBalancer. You can read more about them in the project documentation.
要使用 |
To use |
Attribute resolution mode
在创建 Feign
客户端 Bean 时,我们会解析通过 @FeignClient
标注传递的值。从 4.x
开始,这些值会急切解析。这对于大多数用例来说都是一个好方法,并且允许 AOT 支持。
While creating Feign
client beans, we resolve the values passed via the @FeignClient
annotation. As of 4.x
, the values are being resolved eagerly. This is a good solution for most use-cases, and it also allows for AOT support.
如果您需要属性延迟解析,请将 spring.cloud.openfeign.lazy-attributes-resolution
属性值设为 true
。
If you need the attributes to be resolved lazily, set the spring.cloud.openfeign.lazy-attributes-resolution
property value to true
.
对于 Spring Cloud Contract 测试集成,应使用延迟属性解析。 |
For Spring Cloud Contract test integration, lazy attribute resolution should be used. |
Overriding Feign Defaults
Spring Cloud 对 Feign 支持中的一个核心概念是已命名客户端。每个 feign 客户端是一个组件集的一部分,这些组件共同在按需联系远程服务器时协同工作,并且该组件集有一个名称,您会使用 @FeignClient
标注将其作为应用程序开发人员提供。Spring Cloud 使用 FeignClientsConfiguration
为每个已命名客户端按需创建一个 ApplicationContext
作为 Ensemble
。这(除其他内容外)包含一个 feign.Decoder
、一个 feign.Encoder
和一个 feign.Contract
。可以使用 @FeignClient
标注的 contextId
属性覆盖该组件集的名称。
A central concept in Spring Cloud’s Feign support is that of the named client. Each feign client is part of an ensemble of components that work together to contact a remote server on demand, and the ensemble has a name that you give it as an application developer using the @FeignClient
annotation. Spring Cloud creates a new ensemble as an
ApplicationContext
on demand for each named client using FeignClientsConfiguration
. This contains (amongst other things) an feign.Decoder
, a feign.Encoder
, and a feign.Contract
.
It is possible to override the name of that ensemble by using the contextId
attribute of the @FeignClient
annotation.
Spring Cloud 允许您通过使用 @FeignClient
声明附加配置(在 FeignClientsConfiguration
中)来完全控制 feign 客户端。示例:
Spring Cloud lets you take full control of the feign client by declaring additional configuration (on top of the FeignClientsConfiguration
) using @FeignClient
. Example:
@FeignClient(name = "stores", configuration = FooConfiguration.class)
public interface StoreClient {
//..
}
在这种情况下,客户端由 FeignClientsConfiguration
中的组件以及 FooConfiguration
中的任何组件构成(后者将覆盖前者)。
In this case the client is composed from the components already in FeignClientsConfiguration
together with any in FooConfiguration
(where the latter will override the former).
|
|
除更改 |
Using |
以前,使用 url
属性不需要 name
属性。现在需要使用 name
。
Previously, using the url
attribute, did not require the name
attribute. Using name
is now required.
name
和 url
属性支持占位符。
Placeholders are supported in the name
and url
attributes.
@FeignClient(name = "${feign.name}", url = "${feign.url}")
public interface StoreClient {
//..
}
Spring Cloud OpenFeign 为 feign 提供以下默认 Bean(BeanType
BeanName:ClassName
):
Spring Cloud OpenFeign provides the following beans by default for feign (BeanType
beanName: ClassName
):
-
Decoder
feignDecoder:ResponseEntityDecoder
(which wraps aSpringDecoder
) -
Encoder
feignEncoder:SpringEncoder
-
Logger
feignLogger:Slf4jLogger
-
MicrometerObservationCapability
micrometerObservationCapability: Iffeign-micrometer
is on the classpath andObservationRegistry
is available -
MicrometerCapability
micrometerCapability: Iffeign-micrometer
is on the classpath,MeterRegistry
is available andObservationRegistry
is not available -
CachingCapability
cachingCapability: If@EnableCaching
annotation is used. Can be disabled viaspring.cloud.openfeign.cache.enabled
. -
Contract
feignContract:SpringMvcContract
-
Feign.Builder
feignBuilder:FeignCircuitBreaker.Builder
-
Client
feignClient: If Spring Cloud LoadBalancer is on the classpath,FeignBlockingLoadBalancerClient
is used. If none of them is on the classpath, the default feign client is used.
|
|
若要使用 OkHttpClient 支持的 Feign 客户端和 Http2Client Feign 客户端,请确保您要使用的客户端在类路径中,并将 spring.cloud.openfeign.okhttp.enabled
或 spring.cloud.openfeign.http2client.enabled
分别设为 true
。
To use OkHttpClient-backed Feign clients and Http2Client Feign clients, make sure that the client you want to use is on the classpath and set spring.cloud.openfeign.okhttp.enabled
or spring.cloud.openfeign.http2client.enabled
to true
respectively.
对于 Apache HttpClient 5 支持的 Feign 客户端,只需确保 HttpClient 5 在类路径中即可,但您仍可以通过将 spring.cloud.openfeign.httpclient.hc5.enabled
设为 false
来禁用它在 Feign 客户端中的使用。使用 Apache HC5 时,您可以通过提供 org.apache.hc.client5.http.impl.classic.CloseableHttpClient
Bean 来自定义 HTTP 客户端。
When it comes to the Apache HttpClient 5-backed Feign clients, it’s enough to ensure HttpClient 5 is on the classpath, but you can still disable its use for Feign Clients by setting spring.cloud.openfeign.httpclient.hc5.enabled
to false
.
You can customize the HTTP client used by providing a bean of either org.apache.hc.client5.http.impl.classic.CloseableHttpClient
when using Apache HC5.
您可以通过设置 spring.cloud.openfeign.httpclient.xxx
属性中的值来进一步自定义 http 客户端。仅带有 httpclient
前缀的那些属性将适用于所有客户端,带有 httpclient.hc5
前缀的那些属性适用于 Apache HttpClient 5,带有 httpclient.okhttp
前缀的那些属性适用于 OkHttpClient,带有 httpclient.http2
前缀的那些属性适用于 Http2Client。您可以在附录中找到可以自定义的完整属性列表。如果您无法使用属性配置 Apache HttpClient 5,则有一个 HttpClientBuilderCustomizer
接口用于以编程方式进行配置。
You can further customise http clients by setting values in the spring.cloud.openfeign.httpclient.xxx
properties. The ones prefixed just with httpclient
will work for all the clients, the ones prefixed with httpclient.hc5
to Apache HttpClient 5, the ones prefixed with httpclient.okhttp
to OkHttpClient and the ones prefixed with httpclient.http2
to Http2Client. You can find a full list of properties you can customise in the appendix.
If you can not configure Apache HttpClient 5 by using properties, there is an HttpClientBuilderCustomizer
interface for programmatic configuration.
从 Spring Cloud OpenFeign 4 开始,不再支持 Feign Apache HttpClient 4。我们建议改用 Apache HttpClient 5。 |
Starting with Spring Cloud OpenFeign 4, the Feign Apache HttpClient 4 is no longer supported. We suggest using Apache HttpClient 5 instead. |
Spring Cloud OpenFeign 不 为 feign 提供以下默认 Bean,但仍从应用程序上下文中查找这些类型的 Bean 以创建 feign 客户端:
Spring Cloud OpenFeign does not provide the following beans by default for feign, but still looks up beans of these types from the application context to create the feign client:
-
Logger.Level
-
Retryer
-
ErrorDecoder
-
Request.Options
-
Collection<RequestInterceptor>
-
SetterFactory
-
QueryMapEncoder
-
Capability
(MicrometerObservationCapability
andCachingCapability
are provided by default)
默认情况下,创建一个 Retryer.NEVER_RETRY
Bean,其类型为 Retryer
,这将禁用重试。请注意,此重试行为与 Feign 默认行为不同,在 Feign 默认行为中,它将自动重试 IOException,将它们视为与网络相关的瞬态异常,以及 ErrorDecoder 引发的任何 RetryableException。
A bean of Retryer.NEVER_RETRY
with the type Retryer
is created by default, which will disable retrying.
Notice this retrying behavior is different from the Feign default one, where it will automatically retry IOExceptions,
treating them as transient network related exceptions, and any RetryableException thrown from an ErrorDecoder.
创建一种类型的一个 Bean,并将其放置在 @FeignClient
配置(例如上面的 FooConfiguration
)中,让您可以覆盖所述的每个 Bean。示例:
Creating a bean of one of those type and placing it in a @FeignClient
configuration (such as FooConfiguration
above) allows you to override each one of the beans described. Example:
@Configuration
public class FooConfiguration {
@Bean
public Contract feignContract() {
return new feign.Contract.Default();
}
@Bean
public BasicAuthRequestInterceptor basicAuthRequestInterceptor() {
return new BasicAuthRequestInterceptor("user", "password");
}
}
这会将 SpringMvcContract
替换为 feign.Contract.Default
,并将 RequestInterceptor
添加到 RequestInterceptor
集合中。
This replaces the SpringMvcContract
with feign.Contract.Default
and adds a RequestInterceptor
to the collection of RequestInterceptor
.
我们还可以使用配置属性配置 @FeignClient
。
@FeignClient
also can be configured using configuration properties.
application.yml
spring:
cloud:
openfeign:
client:
config:
feignName:
url: http://remote-service.com
connectTimeout: 5000
readTimeout: 5000
loggerLevel: full
errorDecoder: com.example.SimpleErrorDecoder
retryer: com.example.SimpleRetryer
defaultQueryParameters:
query: queryValue
defaultRequestHeaders:
header: headerValue
requestInterceptors:
- com.example.FooRequestInterceptor
- com.example.BarRequestInterceptor
responseInterceptor: com.example.BazResponseInterceptor
dismiss404: false
encoder: com.example.SimpleEncoder
decoder: com.example.SimpleDecoder
contract: com.example.SimpleContract
capabilities:
- com.example.FooCapability
- com.example.BarCapability
queryMapEncoder: com.example.SimpleQueryMapEncoder
micrometer.enabled: false
本例中的 feignName
指 @FeignClient
value
,它还与 @FeignClient
name
和 @FeignClient
contextId
构成别名。在负载均衡场景中,它还对应服务器应用程序的 serviceId
,此 serviceId
用于检索实例。指定的解码器、重试器和其他类的指定类必须在 Spring 上下文中有一个 bean 或者有一个默认构造函数。
feignName
in this example refers to @FeignClient
value
, that is also aliased with @FeignClient
name
and @FeignClient
contextId
. In a load-balanced scenario, it also corresponds to the serviceId
of the server app that will be used to retrieve the instances. The specified classes for decoders, retryer and other ones must have a bean in the Spring context or have a default constructor.
可以在 @EnableFeignClients
属性 defaultConfiguration
中指定默认配置,类似于上述所述。不同之处在于,此配置将适用于 所有 Feign 客户端。
Default configurations can be specified in the @EnableFeignClients
attribute defaultConfiguration
in a similar manner as described above. The difference is that this configuration will apply to all feign clients.
如果你更愿意使用配置属性配置所有 @FeignClient
,则可以使用 default
feign 名称创建配置属性。
If you prefer using configuration properties to configure all @FeignClient
, you can create configuration properties with default
feign name.
你可以使用 spring.cloud.openfeign.client.config.feignName.defaultQueryParameters
和 spring.cloud.openfeign.client.config.feignName.defaultRequestHeaders
来指定将随名为 feignName
的客户端的每个请求发送的查询参数和标头。
You can use spring.cloud.openfeign.client.config.feignName.defaultQueryParameters
and spring.cloud.openfeign.client.config.feignName.defaultRequestHeaders
to specify query parameters and headers that will be sent with every request of the client named feignName
.
application.yml
spring:
cloud:
openfeign:
client:
config:
default:
connectTimeout: 5000
readTimeout: 5000
loggerLevel: basic
如果我们同时创建 @Configuration
bean 和配置属性,那么配置属性将获胜。它将覆盖 @Configuration
值。但是,如果你想将优先级更改为 @Configuration
,则可以将 spring.cloud.openfeign.client.default-to-properties
更改为 false
。
If we create both @Configuration
bean and configuration properties, configuration properties will win.
It will override @Configuration
values. But if you want to change the priority to @Configuration
,
you can change spring.cloud.openfeign.client.default-to-properties
to false
.
如果我们要创建具有相同名称或 url 的多个 feign 客户端,以便它们指向同一服务器,但每个客户端具有不同的自定义配置,那么我们必须使用 @FeignClient
的 contextId
属性,以避免这些配置 bean 发生名称冲突。
If we want to create multiple feign clients with the same name or url
so that they would point to the same server but each with a different custom configuration then
we have to use contextId
attribute of the @FeignClient
in order to avoid name
collision of these configuration beans.
@FeignClient(contextId = "fooClient", name = "stores", configuration = FooConfiguration.class)
public interface FooClient {
//..
}
@FeignClient(contextId = "barClient", name = "stores", configuration = BarConfiguration.class)
public interface BarClient {
//..
}
还可以配置 FeignClient 以不从父上下文中继承 bean。你可以通过在 FeignClientConfigurer
bean 中覆盖 inheritParentConfiguration()
并返回 false
来做到这一点:
It is also possible to configure FeignClient not to inherit beans from the parent context.
You can do this by overriding the inheritParentConfiguration()
in a FeignClientConfigurer
bean to return false
:
@Configuration
public class CustomConfiguration {
@Bean
public FeignClientConfigurer feignClientConfigurer() {
return new FeignClientConfigurer() {
@Override
public boolean inheritParentConfiguration() {
return false;
}
};
}
}
默认情况下,Feign 客户端不编码斜杠 |
By default, Feign clients do not encode slash |
SpringEncoder
configuration
在我们提供的 SpringEncoder
中,我们将二进制内容类型的字符集设置为 null
,并将所有其他内容类型的字符集设置为 UTF-8
。
In the SpringEncoder
that we provide, we set null
charset for binary content types and UTF-8
for all the other ones.
你可以通过将 spring.cloud.openfeign.encoder.charset-from-content-type
的值设置为 true
来修改此行为,以便从 Content-Type
标头字符集中派生字符集。
You can modify this behaviour to derive the charset from the Content-Type
header charset instead by setting the value of spring.cloud.openfeign.encoder.charset-from-content-type
to true
.
Timeout Handling
我们可以配置默认客户端和命名客户端上的超时。OpenFeign 使用两个超时参数:
We can configure timeouts on both the default and the named client. OpenFeign works with two timeout parameters:
-
connectTimeout
prevents blocking the caller due to the long server processing time. -
readTimeout
is applied from the time of connection establishment and is triggered when returning the response takes too long.
如果服务器未运行或不可用,则数据包会导致 connection refused。通信以错误消息结束或以失败告终。如果将 |
In case the server is not running or available a packet results in connection refused. The communication ends either with an error message or in a fallback. This can happen before the |
Creating Feign Clients Manually
在某些情况下,可能有必要以不使用上述方法的方式自定义 Feign 客户端。在这种情况下,您可以使用 Feign Builder API 创建客户端。以下是一个示例,它使用相同的界面创建了两个 Feign 客户端,但使用单独的请求拦截器配置了每个客户端。
In some cases it might be necessary to customize your Feign Clients in a way that is not possible using the methods above. In this case you can create Clients using the Feign Builder API. Below is an example which creates two Feign Clients with the same interface but configures each one with a separate request interceptor.
@Import(FeignClientsConfiguration.class)
class FooController {
private FooClient fooClient;
private FooClient adminClient;
@Autowired
public FooController(Client client, Encoder encoder, Decoder decoder, Contract contract, MicrometerObservationCapability micrometerObservationCapability) {
this.fooClient = Feign.builder().client(client)
.encoder(encoder)
.decoder(decoder)
.contract(contract)
.addCapability(micrometerObservationCapability)
.requestInterceptor(new BasicAuthRequestInterceptor("user", "user"))
.target(FooClient.class, "https://PROD-SVC");
this.adminClient = Feign.builder().client(client)
.encoder(encoder)
.decoder(decoder)
.contract(contract)
.addCapability(micrometerObservationCapability)
.requestInterceptor(new BasicAuthRequestInterceptor("admin", "admin"))
.target(FooClient.class, "https://PROD-SVC");
}
}
在上述示例中 |
In the above example |
|
|
Feign |
The Feign |
你还可以使用 Builder
来配置 FeignClient 以不从父上下文中继承 bean。你可以通过在 Builder
上调用 inheritParentContext(false)
来做到这一点。
You can also use the Builder`to configure FeignClient not to inherit beans from the parent context.
You can do this by overriding calling `inheritParentContext(false)
on the Builder
.
Feign Spring Cloud CircuitBreaker Support
如果 Spring Cloud CircuitBreaker 位于类路径中并且 spring.cloud.openfeign.circuitbreaker.enabled=true
,则 Feign 将使用断路器包装所有方法。
If Spring Cloud CircuitBreaker is on the classpath and spring.cloud.openfeign.circuitbreaker.enabled=true
, Feign will wrap all methods with a circuit breaker.
要按客户端禁用 Spring Cloud CircuitBreaker 支持,请创建一个带有“prototype”范围的纯 Feign.Builder
,例如:
To disable Spring Cloud CircuitBreaker support on a per-client basis create a vanilla Feign.Builder
with the "prototype" scope, e.g.:
@Configuration
public class FooConfiguration {
@Bean
@Scope("prototype")
public Feign.Builder feignBuilder() {
return Feign.builder();
}
}
断路器名称遵循以下模式:<feignClientClassName>#<calledMethod>(<parameterTypes>)
。使用具有 FooClient
接口的 @FeignClient
进行调用,且被调用的接口方法没有参数,则断路器名称将为 FooClient#bar()
。
The circuit breaker name follows this pattern <feignClientClassName>#<calledMethod>(<parameterTypes>)
. When calling a @FeignClient
with FooClient
interface and the called interface method that has no parameters is bar
then the circuit breaker name will be FooClient#bar()
.
截至 2020.0.2,断路器名称模式已从 |
As of 2020.0.2, the circuit breaker name pattern has changed from |
通过提供 CircuitBreakerNameResolver
的 bean,你可以更改断路器名称模式。
Providing a bean of CircuitBreakerNameResolver
, you can change the circuit breaker name pattern.
@Configuration
public class FooConfiguration {
@Bean
public CircuitBreakerNameResolver circuitBreakerNameResolver() {
return (String feignClientName, Target<?> target, Method method) -> feignClientName + "_" + method.getName();
}
}
要启用 Spring Cloud CircuitBreaker 组,请将 spring.cloud.openfeign.circuitbreaker.group.enabled
属性设置为 true
(默认为 false
)。
To enable Spring Cloud CircuitBreaker group set the spring.cloud.openfeign.circuitbreaker.group.enabled
property to true
(by default false
).
Configuring CircuitBreakers With Configuration Properties
你可以通过配置属性配置断路器。
You can configure CircuitBreakers via configuration properties.
例如,如果你有这个 Feign 客户端
For example, if you had this Feign client
@FeignClient(url = "http://localhost:8080")
public interface DemoClient {
@GetMapping("demo")
String getDemo();
}
使用配置属性进行配置的方法如下:
You could configure it using configuration properties by doing the following
spring:
cloud:
openfeign:
circuitbreaker:
enabled: true
alphanumeric-ids:
enabled: true
resilience4j:
circuitbreaker:
instances:
DemoClientgetDemo:
minimumNumberOfCalls: 69
timelimiter:
instances:
DemoClientgetDemo:
timeoutDuration: 10s
如果你想切换回 Spring Cloud 2022.0.0 之前使用的断路器名称,你可以将 |
If you want to switch back to the circuit breaker names used prior to Spring Cloud
2022.0.0 you can set |
Feign Spring Cloud CircuitBreaker Fallbacks
Spring Cloud CircuitBreaker 支持回退概念:在服务调用失败或服务熔断时执行的默认代码路径。要针对给定的 @FeignClient
启用回退,请将 fallback
属性设置为实现回退的类名。还需要将你的实现声明为 Spring Bean。
Spring Cloud CircuitBreaker supports the notion of a fallback: a default code path that is executed when the circuit is open or there is an error. To enable fallbacks for a given @FeignClient
set the fallback
attribute to the class name that implements the fallback. You also need to declare your implementation as a Spring bean.
@FeignClient(name = "test", url = "http://localhost:${server.port}/", fallback = Fallback.class)
protected interface TestClient {
@GetMapping("/hello")
Hello getHello();
@GetMapping("/hellonotfound")
String getException();
}
@Component
static class Fallback implements TestClient {
@Override
public Hello getHello() {
throw new NoFallbackAvailableException("Boom!", new RuntimeException());
}
@Override
public String getException() {
return "Fixed response";
}
}
如果需要访问触发回退的原因,可以在 @FeignClient
内使用 fallbackFactory
属性。
If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory
attribute inside @FeignClient
.
@FeignClient(name = "testClientWithFactory", url = "http://localhost:${server.port}/",
fallbackFactory = TestFallbackFactory.class)
protected interface TestClientWithFactory {
@GetMapping("/hello")
Hello getHello();
@GetMapping("/hellonotfound")
String getException();
}
@Component
static class TestFallbackFactory implements FallbackFactory<FallbackWithFactory> {
@Override
public FallbackWithFactory create(Throwable cause) {
return new FallbackWithFactory();
}
}
static class FallbackWithFactory implements TestClientWithFactory {
@Override
public Hello getHello() {
throw new NoFallbackAvailableException("Boom!", new RuntimeException());
}
@Override
public String getException() {
return "Fixed response";
}
}
Feign and @Primary
在将 Feign 与 Spring Cloud CircuitBreaker 回退一起使用时,ApplicationContext
中有多个相同类型的 Bean。由于没有确切的一个 Bean 或被标记为主 Bean 的 Bean,因此会导致 @Autowired
无法使用。为了解决此问题,Spring Cloud OpenFeign 将所有 Feign 实例标记为 @Primary
,以便 Spring Framework 知道注入哪个 Bean。在某些情况下,可能不希望这样做。要关闭此行为,请将 @FeignClient
的 primary
属性设置为 false。
When using Feign with Spring Cloud CircuitBreaker fallbacks, there are multiple beans in the ApplicationContext
of the same type. This will cause @Autowired
to not work because there isn’t exactly one bean, or one marked as primary. To work around this, Spring Cloud OpenFeign marks all Feign instances as @Primary
, so Spring Framework will know which bean to inject. In some cases, this may not be desirable. To turn off this behavior set the primary
attribute of @FeignClient
to false.
@FeignClient(name = "hello", primary = false)
public interface HelloClient {
// methods here
}
Feign Inheritance Support
Feign 通过单继承接口支持样板 API。这使你可以将常见操作分组到方便的基本接口中。
Feign supports boilerplate apis via single-inheritance interfaces. This allows grouping common operations into convenient base interfaces.
public interface UserService {
@GetMapping("/users/{id}")
User getUser(@PathVariable("id") long id);
}
@RestController
public class UserResource implements UserService {
}
package project.user;
@FeignClient("users")
public interface UserClient extends UserService {
}
@FeignClient
接口不应在服务器和客户端之间共享,而且使用 @RequestMapping
在类级别注释 @FeignClient
接口也不再受支持。
@FeignClient
interfaces should not be shared between server and client and annotating @FeignClient
interfaces with @RequestMapping
on class level is no longer supported.
[[feign-request/response-compression]]=== Feign 请求/响应压缩
[[feign-request/response-compression]] === Feign request/response compression
你可以考虑为 Feign 请求启用请求或响应 GZIP 压缩。你可以通过启用以下一个属性来实现此目的:
You may consider enabling the request or response GZIP compression for your Feign requests. You can do this by enabling one of the properties:
spring.cloud.openfeign.compression.request.enabled=true
spring.cloud.openfeign.compression.response.enabled=true
Feign 请求压缩提供的设置与你可以为 Web 服务器设置的设置类似:
Feign request compression gives you settings similar to what you may set for your web server:
spring.cloud.openfeign.compression.request.enabled=true
spring.cloud.openfeign.compression.request.mime-types=text/xml,application/xml,application/json
spring.cloud.openfeign.compression.request.min-request-size=2048
这些属性使你可以有选择地指定压缩的媒体类型和最小请求阈值长度。
These properties allow you to be selective about the compressed media types and minimum request threshold length.
由于 OkHttpClient 使用“透明”压缩,当 |
Since the OkHttpClient uses "transparent" compression, that is disabled if the |
Feign logging
为创建的每个 Feign 客户端都会创建一个日志记录器。默认情况下,日志记录器的名称是用于创建 Feign 客户端的接口的全类名。Feign 日志记录只响应 DEBUG
级别。
A logger is created for each Feign client created. By default, the name of the logger is the full class name of the interface used to create the Feign client. Feign logging only responds to the DEBUG
level.
logging.level.project.user.UserClient: DEBUG
你可以针对每个客户端配置的 Logger.Level
对象会告知 Feign 记录的详细信息。选项包括:
The Logger.Level
object that you may configure per client, tells Feign how much to log. Choices are:
-
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.
例如,下面的示例会将 Logger.Level
设置为 FULL
:
For example, the following would set the Logger.Level
to FULL
:
@Configuration
public class FooConfiguration {
@Bean
Logger.Level feignLoggerLevel() {
return Logger.Level.FULL;
}
}
Feign Capability support
Feign 功能公开了核心 Feign 组件,以便可以修改这些组件。例如,功能可以获取 Client
、_decorate_它,并将装饰后的实例返回给 Feign。Micrometer 的支持就是此功能的出色实际示例。请参阅 Micrometer Support。
The Feign capabilities expose core Feign components so that these components can be modified. For example, the capabilities can take the Client
, decorate it, and give the decorated instance back to Feign.
The support for Micrometer is a good real-life example for this. See Micrometer Support.
创建一或多个 Capability
Bean 并将其置于 @FeignClient
配置中,这样可以注册这些 Bean 并修改所涉及客户端的行为。
Creating one or more Capability
beans and placing them in a @FeignClient
configuration lets you register them and modify the behavior of the involved client.
@Configuration
public class FooConfiguration {
@Bean
Capability customCapability() {
return new CustomCapability();
}
}
Micrometer Support
如果满足以下所有条件,则会创建一个 MicrometerObservationCapability
Bean 并进行注册,以便你的 Feign 客户端可以由 Micrometer 观测:
If all of the following conditions are true, a MicrometerObservationCapability
bean is created and registered so that your Feign client is observable by Micrometer:
-
feign-micrometer
is on the classpath -
A
ObservationRegistry
bean is available -
feign micrometer properties are set to
true
(by default)-
spring.cloud.openfeign.micrometer.enabled=true
(for all clients) -
spring.cloud.openfeign.client.config.feignName.micrometer.enabled=true
(for a single client)
-
如果你的应用程序已经使用了 Micrometer,启用此功能只需将 |
If your application already uses Micrometer, enabling this feature is as simple as putting |
你还可以通过以下方式禁用该功能:
You can also disable the feature by either:
-
excluding
feign-micrometer
from your classpath -
setting one of the feign micrometer properties to
false
-
spring.cloud.openfeign.micrometer.enabled=false
-
spring.cloud.openfeign.client.config.feignName.micrometer.enabled=false
-
|
|
你还可以通过注册自己的 Bean 来自定义 MicrometerObservationCapability
:
You can also customize the MicrometerObservationCapability
by registering your own bean:
@Configuration
public class FooConfiguration {
@Bean
public MicrometerObservationCapability micrometerObservationCapability(ObservationRegistry registry) {
return new MicrometerObservationCapability(registry);
}
}
仍然可以使用 MicrometerCapability
与 Feign(仅指标支持),你需要禁用 Micrometer 支持(spring.cloud.openfeign.micrometer.enabled=false
)并创建一个 MicrometerCapability
Bean:
It is still possible to use MicrometerCapability
with Feign (metrics-only support), you need to disable Micrometer support (spring.cloud.openfeign.micrometer.enabled=false
) and create a MicrometerCapability
bean:
@Configuration
public class FooConfiguration {
@Bean
public MicrometerCapability micrometerCapability(MeterRegistry meterRegistry) {
return new MicrometerCapability(meterRegistry);
}
}
Feign Caching
如果使用了 @EnableCaching
注解,则会创建并注册 CachingCapability
Bean,以便你的 Feign 客户端可以识别其界面上的 @Cache
注解:
If @EnableCaching
annotation is used, a CachingCapability
bean is created and registered so that your Feign client recognizes @Cache*
annotations on its interface:
public interface DemoClient {
@GetMapping("/demo/{filterParam}")
@Cacheable(cacheNames = "demo-cache", key = "#keyParam")
String demoEndpoint(String keyParam, @PathVariable String filterParam);
}
你还可以通过属性 spring.cloud.openfeign.cache.enabled=false
禁用该功能。
You can also disable the feature via property spring.cloud.openfeign.cache.enabled=false
.
Feign @QueryMap support
Spring Cloud OpenFeign 提供等效的 @SpringQueryMap
注释,用于将 POJO 或 Map 参数注释为查询参数映射。
Spring Cloud OpenFeign provides an equivalent @SpringQueryMap
annotation, which
is used to annotate a POJO or Map parameter as a query parameter map.
例如,Params
类定义参数 param1
和 param2
:
For example, the Params
class defines parameters param1
and param2
:
// Params.java
public class Params {
private String param1;
private String param2;
// [Getters and setters omitted for brevity]
}
以下 Feign 客户端使用 @SpringQueryMap
注释,来使用 Params
类:
The following feign client uses the Params
class by using the @SpringQueryMap
annotation:
@FeignClient("demo")
public interface DemoTemplate {
@GetMapping(path = "/demo")
String demoEndpoint(@SpringQueryMap Params params);
}
如果您需要更多控制生成的查询参数映射,则可以实现自定义 QueryMapEncoder
Bean。
If you need more control over the generated query parameter map, you can implement a custom QueryMapEncoder
bean.
HATEOAS support
Spring 提供了一些 API 来创建遵循 HATEOAS原则的 REST 表示: Spring Hateoas和 Spring Data REST。
Spring provides some APIs to create REST representations that follow the HATEOAS principle, Spring Hateoas and Spring Data REST.
如果您的项目使用 org.springframework.boot:spring-boot-starter-hateoas
starter 或 org.springframework.boot:spring-boot-starter-data-rest
starter,则默认启用 Feign HATEOAS 支持。
If your project use the org.springframework.boot:spring-boot-starter-hateoas
starter
or the org.springframework.boot:spring-boot-starter-data-rest
starter, Feign HATEOAS support is enabled by default.
启用 HATEOAS 支持后,允许 Feign 客户端序列化和反序列化 HATEOAS 表示模型: EntityModel、 CollectionModel和 PagedModel。
When HATEOAS support is enabled, Feign clients are allowed to serialize and deserialize HATEOAS representation models: EntityModel, CollectionModel and PagedModel.
@FeignClient("demo")
public interface DemoTemplate {
@GetMapping(path = "/stores")
CollectionModel<Store> getStores();
}
Spring @MatrixVariable Support
Spring Cloud OpenFeign 为 Spring @MatrixVariable
注释提供支持。
Spring Cloud OpenFeign provides support for the Spring @MatrixVariable
annotation.
如果将映射作为方法参数传递,则通过使用 =
连接映射中的键值对来创建 @MatrixVariable
路径段。
If a map is passed as the method argument, the @MatrixVariable
path segment is created by joining key-value pairs from the map with a =
.
如果传递不同的对象,则使用 =
将 @MatrixVariable
注释中提供的 name
(如果已定义)或带注释的变量名称与提供的函数参数连接。
If a different object is passed, either the name
provided in the @MatrixVariable
annotation (if defined) or the annotated variable name is
joined with the provided method argument using =
.
- IMPORTANT
-
Even though, on the server side, Spring does not require the users to name the path segment placeholder same as the matrix variable name, since it would be too ambiguous on the client side, Spring Cloud OpenFeign requires that you add a path segment placeholder with a name matching either the
name
provided in the@MatrixVariable
annotation (if defined) or the annotated variable name.
例如:
For example:
@GetMapping("/objects/links/{matrixVars}")
Map<String, List<String>> getObjects(@MatrixVariable Map<String, List<String>> matrixVars);
请注意,变量名称和路径段占位符都称为 matrixVars
。
Note that both variable name and the path segment placeholder are called matrixVars
.
@FeignClient("demo")
public interface DemoTemplate {
@GetMapping(path = "/stores")
CollectionModel<Store> getStores();
}
Feign CollectionFormat
support
通过提供 @CollectionFormat
注释,我们支持 feign.CollectionFormat
。您可以通过将所需的 feign.CollectionFormat
作为注释值传递,用它注释 Feign 客户端方法(或整个类以影响所有方法)。
We support feign.CollectionFormat
by providing the @CollectionFormat
annotation.
You can annotate a Feign client method (or the whole class to affect all methods) with it by passing the desired feign.CollectionFormat
as annotation value.
在以下示例中,使用 CSV
格式来处理方法,而不是默认的 EXPLODED
格式。
In the following example, the CSV
format is used instead of the default EXPLODED
to process the method.
@FeignClient(name = "demo")
protected interface DemoFeignClient {
@CollectionFormat(feign.CollectionFormat.CSV)
@GetMapping(path = "/test")
ResponseEntity performRequest(String test);
}
Reactive Support
因为 OpenFeign project目前不支持响应式客户端,例如 Spring WebClient,所以 Spring Cloud OpenFeign 也不支持。
As the OpenFeign project does not currently support reactive clients, such as Spring WebClient, neither does Spring Cloud OpenFeign.
由于 Spring Cloud OpenFeign 项目现在被认为已完成功能,因此即使它在上游项目中可用,我们也不计划添加支持。我们建议改为迁移到 Spring Interface Clients。它同时支持阻塞和响应式堆栈。
SinceSpring Cloud OpenFeign project is now considered feature-complete, we’re not planning on adding support even if it becomes available in the upstream project. We suggest migrating over to Spring Interface Clients instead. Both blocking and reactive stacks are supported there.
在完成之前,我们建议针对 Spring WebClient 支持使用 feign-reactive。
Until that is done, we recommend using feign-reactive for Spring WebClient support.
Early Initialization Errors
我们不鼓励在应用程序生命周期的早期阶段(处理配置和初始化 Bean 时)使用 Feign 客户端。不支持在 Bean 初始化期间使用客户端。
We discourage using Feign clients in the early stages of application lifecycle, while processing configurations and initialising beans. Using the clients during bean initialisation is not supported.
同样,根据您使用 Feign 客户端的方式,您在启动应用程序时可能会看到初始化错误。要解决此问题,可以在自动装配客户端时使用 ObjectProvider
。
Similarly, depending on how you are using your Feign clients, you may see initialization errors when starting your application. To work around this problem you can use an ObjectProvider
when autowiring your client.
@Autowired
ObjectProvider<TestFeignClient> testFeignClient;
Spring Data Support
如果类路径中存在 Jackson Databind 和 Spring Data Commons,将自动添加 org.springframework.data.domain.Page
和 org.springframework.data.domain.Sort
的转换器。
If Jackson Databind and Spring Data Commons are on the classpath, converters for org.springframework.data.domain.Page
and org.springframework.data.domain.Sort
will be added automatically.
若要禁用此行为,请设置
To disable this behaviour set
spring.cloud.openfeign.autoconfiguration.jackson.enabled=false
有关详细信息,请参阅 org.springframework.cloud.openfeign.FeignAutoConfiguration.FeignJacksonConfiguration
。
See org.springframework.cloud.openfeign.FeignAutoConfiguration.FeignJacksonConfiguration
for details.
Spring @RefreshScope
Support
如果启用了 Feign 客户端刷新,则会使用以下内容创建每个 Feign 客户端:
If Feign client refresh is enabled, each Feign client is created with:
-
feign.Request.Options
as a refresh-scoped bean. This means properties such asconnectTimeout
andreadTimeout
can be refreshed against any Feign client instance. -
A url wrapped under
org.springframework.cloud.openfeign.RefreshableUrl
. This means the URL of Feign client, if defined withspring.cloud.openfeign.client.config.{feignName}.url
property, can be refreshed against any Feign client instance.
您可以通过 POST /actuator/refresh
刷新这些属性。
You can refresh these properties through POST /actuator/refresh
.
默认禁用 Feign 客户端中的刷新行为。使用以下属性启用刷新行为:
By default, refresh behavior in Feign clients is disabled. Use the following property to enable refresh behavior:
spring.cloud.openfeign.client.refresh-enabled=true
不要使用 |
DO NOT annotate the |
OAuth2 Support
通过将 spring-boot-starter-oauth2-client
依赖项添加到项目并设置以下标记,可以启用 OAuth2 支持:
OAuth2 support can be enabled by adding the spring-boot-starter-oauth2-client
dependency to your project and setting following flag:
spring.cloud.openfeign.oauth2.enabled=true
当将该标记设置为 true 时,如果存在 oauth2 客户端上下文资源详细信息,则会创建一个 OAuth2AccessTokenInterceptor
类 bean。在每个请求之前,拦截器解析所需的访问令牌并将它包含为标头。OAuth2AccessTokenInterceptor
使用 OAuth2AuthorizedClientManager
获取包含 OAuth2AccessToken
的 OAuth2AuthorizedClient
。如果用户使用 spring.cloud.openfeign.oauth2.clientRegistrationId
属性指定了 OAuth2 clientRegistrationId
,则将使用该值来检索令牌。如果未检索令牌或未指定 clientRegistrationId
,则将使用从 url
主机段检索到的 serviceId
。
When the flag is set to true, and the oauth2 client context resource details are present, a bean of class OAuth2AccessTokenInterceptor
is created. Before each request, the interceptor resolves the required access token and includes it as a header.
OAuth2AccessTokenInterceptor
uses the OAuth2AuthorizedClientManager
to get OAuth2AuthorizedClient
that holds an OAuth2AccessToken
. If the user has specified an OAuth2 clientRegistrationId
using the spring.cloud.openfeign.oauth2.clientRegistrationId
property, it will be used to retrieve the token. If the token is not retrieved or the clientRegistrationId
has not been specified, the serviceId
retrieved from the url
host segment will be used.
- TIP
-
Using the
serviceId
as OAuth2 client registrationId is convenient for load-balanced Feign clients. For non-load-balanced ones, the property-basedclientRegistrationId
is a suitable approach. - TIP
-
If you do not want to use the default setup for the
OAuth2AuthorizedClientManager
, you can just instantiate a bean of this type in your configuration.
Transform the load-balanced HTTP request
您可以使用选定的 ServiceInstance
来转换负载均衡的 HTTP 请求。
You can use the selected ServiceInstance
to transform the load-balanced HTTP Request.
对于 Request
,您需要按如下所示实现和定义 LoadBalancerFeignRequestTransformer
:
For Request
, you need to implement and define LoadBalancerFeignRequestTransformer
, as follows:
@Bean
public LoadBalancerFeignRequestTransformer transformer() {
return new LoadBalancerFeignRequestTransformer() {
@Override
public Request transformRequest(Request request, ServiceInstance instance) {
Map<String, Collection<String>> headers = new HashMap<>(request.headers());
headers.put("X-ServiceId", Collections.singletonList(instance.getServiceId()));
headers.put("X-InstanceId", Collections.singletonList(instance.getInstanceId()));
return Request.create(request.httpMethod(), request.url(), headers, request.body(), request.charset(),
request.requestTemplate());
}
};
}
如果定义了多个转换器,则按 Bean 定义的顺序应用它们。或者,您可以使用 LoadBalancerFeignRequestTransformer.DEFAULT_ORDER
来指定顺序。
If multiple transformers are defined, they are applied in the order in which beans are defined.
Alternatively, you can use LoadBalancerFeignRequestTransformer.DEFAULT_ORDER
to specify the order.
X-Forwarded Headers Support
可以通过设置以下标记来启用 X-Forwarded-Host
和 X-Forwarded-Proto
的支持:
X-Forwarded-Host
and X-Forwarded-Proto
support can be enabled by setting following flag:
spring.cloud.loadbalancer.x-forwarded.enabled=true
Supported Ways To Provide URL To A Feign Client
您可以使用以下任何一种方式为 Feign 客户端提供 URL:
You can provide a URL to a Feign client in any of the following ways:
Case | Example | Details |
---|---|---|
The URL is provided in the |
|
The URL is resolved from the |
The URL is provided in the |
|
The URL is resolved from the |
The URL is not provided in the |
|
The URL is resolved from configuration properties, without load-balancing. If
|
The URL is neither provided in the |
|
The URL is resolved from |
AOT and Native Image Support
Spring Cloud OpenFeign 支持 Spring AOT 转换和本地映像,但仅当禁用刷新模式、停用 Feign 客户端刷新(默认设置)和 xref:spring-cloud-openfeign.adoc#attribute-resolution-mode[lazy @FeignClient
属性分辨率(默认设置)时才支持。
Spring Cloud OpenFeign supports Spring AOT transformations and native images, however, only with refresh mode disabled, Feign clients refresh disabled (default setting) and lazy @FeignClient
attribute resolution disabled (default setting).
如果你想在 AOT 或原生镜像模式下运行 Spring Cloud OpenFeign 客户端,请确保将 spring.cloud.refresh.enabled
设置为 false
。
If you want to run Spring Cloud OpenFeign clients in AOT or native image modes, make sure to set spring.cloud.refresh.enabled
to false
.
如果你想在 AOT 或原生镜像模式下运行 Spring Cloud OpenFeign 客户端,请确保未将 |
If you want to run Spring Cloud OpenFeign clients in AOT or native image modes, ensure |
如果你想在 AOT 或原生镜像模式下运行 Spring Cloud OpenFeign 客户端,请确保未将 |
If you want to run Spring Cloud OpenFeign clients in AOT or native image modes, ensure |
不过,如果你通过属性设置 |
However, if you set the |
Configuration properties
要查看所有 Spring Cloud OpenFeign 相关配置属性的列表,请查看 the Appendix page。
To see the list of all Spring Cloud OpenFeign related configuration properties please check the Appendix page.