从官方文档中去发现变化的点：
官方关于Okhttp from 3.x to 4.x
官方关于Spring-cloud+feign from 2.2.x
官方关于Spring-cloud+feign from 4.1.x
- spring-cloud-openfeign 变化对比
- 如何引入feign?
- 如何加载feign?
- 如何申明一个client？
- 关于load-balancer
- 关于资源加载
- 关于启动默认的httpclient和okhttp的配置
- 关于 SpringEncoder 配置
- 关于熔断的配置
- 关于请求/响应的压缩
- 关于SpringData的支持
- 其他 4.1.x的新特性
- SpringBoot + SpringCloud + Feign + Okhttp 实践示例
spring-cloud-openfeign 变化对比
如何引入feign?
<dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency>
如何加载feign?
通过注解：@EnableFeignClients，开始feign的注入
如何申明一个client？
@FeignClient("stores")
public interface StoreClient {@RequestMapping(method = RequestMethod.GET, value = "/stores")List<Store> getStores();@RequestMapping(method = RequestMethod.GET, value = "/stores")Page<Store> getStores(Pageable pageable);@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")Store update(@PathVariable("storeId") Long storeId, Store store);@RequestMapping(method = RequestMethod.DELETE, value = "/stores/{storeId:\\d+}")void delete(@PathVariable Long storeId);
}
关于load-balancer
2.2.x中
@FeignClient 会创建一个Ribbon load-balancer 或 Spring Cloud LoadBalancer. 取决于spring.cloud.loadbalancer.ribbon.enabled 配置项，如果true则使用Ribbon load-balancer ，如果false则使用Spring Cloud LoadBalancer
4.1.x中
@FeignClient 直接创建一个 Spring Cloud LoadBalancer client
关于资源加载
4.1.x中
@FeignClient 注解被解析的时间更早，便于很多逻辑的处理，如果想要懒加载需要显式指定
spring.cloud.openfeign.lazy-attributes-resolution=true
springcloud 会通过 FeignClientsConfiguration ，将feignclient加入应用上下文
配置包含三部分，一个 feign.Decoder, 一个 feign.Encoder, 和 一个 feign.Contract
可以通过 @FeignClient 的contextId来覆盖这几个默认的
springcloud支持不同的client指定不同配置，@FeignClient(name = "stores", configuration = FooConfiguration.class)
FooConfiguration 不需要用 @Configuration 进行注释，否则他将成为client的默认配置
spring-cloud-starter-openfeign 支持 spring-cloud-starter-loadbalancer，去除了spring-cloud-starter-netflix-ribbon 的默认支持
关于启动默认的httpclient和okhttp的配置
配置项的label上有比较大的区别，从feign的配置迁移到了spring.cloud.openfeign的命名上，主要还是源于feign自身的调整
| 配置项 | 2.2.x | 4.1.x |
|---|---|---|
| ApacheHttpClient | feign.httpclient.enabled=true | spring.cloud.openfeign.httpclient.enabled=true |
| ApacheHC5 | feign.httpclient.hc5.enabled=true | spring.cloud.openfeign.httpclient.hc5.enabled=true |
| OkHttpClient | feign.okhttp.enabled=true | spring.cloud.openfeign.okhttp.enabled=true |
| Http2Client | - | spring.cloud.openfeign.http2client.enabled=true |
从Spring Cloud OpenFeign 4开始，HttpClient 4将不再支持，建议使用HttpClient 5
2.2.x application.yaml 示例：
feign:client:config:feignName:connectTimeout: 5000readTimeout: 5000loggerLevel: fullerrorDecoder: com.example.SimpleErrorDecoderretryer: com.example.SimpleRetryerdefaultQueryParameters:query: queryValuedefaultRequestHeaders:header: headerValuerequestInterceptors:- com.example.FooRequestInterceptor- com.example.BarRequestInterceptordecode404: falseencoder: com.example.SimpleEncoderdecoder: com.example.SimpleDecodercontract: com.example.SimpleContract4.1.x application.yaml 示例：
spring:cloud:openfeign:client:config:feignName:url: http://remote-service.comconnectTimeout: 5000readTimeout: 5000loggerLevel: fullerrorDecoder: com.example.SimpleErrorDecoderretryer: com.example.SimpleRetryerdefaultQueryParameters:query: queryValuedefaultRequestHeaders:header: headerValuerequestInterceptors:- com.example.FooRequestInterceptor- com.example.BarRequestInterceptorresponseInterceptor: com.example.BazResponseInterceptordismiss404: falseencoder: com.example.SimpleEncoderdecoder: com.example.SimpleDecodercontract: com.example.SimpleContractcapabilities:- com.example.FooCapability- com.example.BarCapabilityqueryMapEncoder: com.example.SimpleQueryMapEncodermicrometer.enabled: false
关于 SpringEncoder 配置
| 配置项 | 2.2.x | 4.1.x |
|---|---|---|
| 改变默认utf-8的配置 | feign.encoder.charset-from-content-type=true | spring.cloud.openfeign.encoder.charset-from-content-type=true |
关于熔断的配置
| 配置项 | 2.2.x | 4.1.x |
|---|---|---|
| 熔断 | feign.hystrix.enabled=true | spring.cloud.openfeign.circuitbreaker.enabled=true |
从2020.0.2开始，熔断器的命名规则从 <feignClientName>_<calledMethod> 变为 <feignClientClassName>#<calledMethod>(<parameterTypes>)，比如FooClient#bar()
关于请求/响应的压缩
| 配置项 | 2.2.x | 4.1.x |
|---|---|---|
| 配置压缩 | feign.compression.request.enabled=true feign.compression.response.enabled=true | spring.cloud.openfeign.compression.request.enabled=true spring.cloud.openfeign.compression.response.enabled=true |
4.1.x
由于 OkHttpClient 使用“透明”压缩，如果存在 content-encoding 或 accept-encoding 标头，则禁用该压缩，因此当类路径上存在 feign.okhttp.OkHttpClient 并且 spring.cloud.openfeign.okhttp.enabled 设置为 true 时，我们不会启用压缩
关于SpringData的支持
2.2.x中
feign.autoconfiguration.jackson.enabled=true 开启
4.1.x中
只要Jackson Databind 和 Spring Data Commons 被引入了，就会自动开启，如果想禁用，主动配置 spring.cloud.openfeign.autoconfiguration.jackson.enabled=false
其他 4.1.x的新特性
- 支持Spring @RefreshScope
spring.cloud.openfeign.client.refresh-enabled=true - 支持 OAuth2
spring.cloud.openfeign.oauth2.enabled=true - 转换负载均衡的 HTTP 请求，定义并实现LoadBalancerFeignRequestTransformer
- 支持X-Forwarded Headers
spring.cloud.loadbalancer.x-forwarded.enabled=true
SpringBoot + SpringCloud + Feign + Okhttp 实践示例
基础对象：
public class PostInfo {private Integer id;private Integer userId;private String title;private String body;public Integer getId() {return id;}public void setId(final Integer id) {this.id = id;}public Integer getUserId() {return userId;}public void setUserId(final Integer userId) {this.userId = userId;}public String getTitle() {return title;}public void setTitle(final String title) {this.title = title;}public String getBody() {return body;}public void setBody(final String body) {this.body = body;}@Overridepublic String toString() {return "PostInfo{" +"id=" + id +", userId=" + userId +", title='" + title + '\'' +", body='" + body + '\'' +'}';}
}@FeignClient(value = "jplaceholder", url = "https://jsonplaceholder.typicode.com/")
public interface PostService {@RequestMapping(method = RequestMethod.GET, value = "/posts")List<PostInfo> getPosts();@RequestMapping(method = RequestMethod.GET, value = "/posts/{postId}", produces = "application/json")PostInfo getPostById(@PathVariable("postId") Long postId);@RequestMapping(method = RequestMethod.POST, value = "/posts", produces = "application/json")PostInfo savePost(@RequestBody PostInfo postInfo);@RequestMapping(method = RequestMethod.PATCH, value = "/posts", produces = "application/json")PostInfo updatePost(@RequestBody PostInfo postInfo);@RequestMapping(method = RequestMethod.DELETE, value = "/posts/{postId}", produces = "application/json")void deletePost(@PathVariable("postId") Long postId);
}@RestController
@RequestMapping("/v1")
public class TestController {@Autowiredprivate PostService postService;@GetMapping("/feign/post")public String feignPostRequest(){return postService.getPostById(1L).toString();}
}
差异基本就在配置项上
springboot2.x pom.xml
<properties><java.version>1.8</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>2.3.12.RELEASE</spring-boot.version><spring-cloud.version>Hoxton.SR12</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-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope><exclusions><exclusion><groupId>org.junit.vintage</groupId><artifactId>junit-vintage-engine</artifactId></exclusion></exclusions></dependency><dependency><groupId>io.github.openfeign</groupId><artifactId>feign-okhttp</artifactId><version>10.12</version></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>1.8</source><target>1.8</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.learning.cloudforfeignokhttp3.CloudForFeignOkhttp3Application</mainClass><skip>true</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build>
springboot2.x application.yaml
server:port: 8088
feign:okhttp:enabled: truehttpclient:enabled: false
debug: true
springboot3.x pom.xml
<properties><java.version>17</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>3.2.0</spring-boot.version><spring-cloud.version>2023.0.0</spring-cloud.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-starter-openfeign</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>io.github.openfeign</groupId><artifactId>feign-okhttp</artifactId><version>13.0</version></dependency></dependencies><dependencyManagement><dependencies><dependency><groupId>org.springframework.cloud</groupId><artifactId>spring-cloud-dependencies</artifactId><version>${spring-cloud.version}</version><type>pom</type><scope>import</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope></dependency></dependencies></dependencyManagement><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration><source>17</source><target>17</target><encoding>UTF-8</encoding></configuration></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>${spring-boot.version}</version><configuration><mainClass>com.learning.cloudforfeign4.CloudForFeignOkhttp4Application</mainClass><skip>true</skip></configuration><executions><execution><id>repackage</id><goals><goal>repackage</goal></goals></execution></executions></plugin></plugins></build><repositories><repository><id>spring-milestones</id><name>Spring Milestones</name><url>https://repo.spring.io/milestone</url><snapshots><enabled>false</enabled></snapshots></repository></repositories>
springboot3.x application.yaml
server:port: 8089
spring:cloud:openfeign:okhttp:enabled: truehttpclient:enabled: false
debug: true
