openfeign內建sentinel實作服務降級
- 使用openfeign調用服務(不含sentinel)
-
- 代碼
- 測試
- openfeign內建sentinel實作服務降級
-
- 引入sentinel相關環境
- 編寫@FeignClient注解接口的實作類
- 在服務提供者中,人為添加異常代碼,以供測試 / 或者不啟動服務提供者,服務消費者找不到服務提供者,也會報錯,同樣能夠達到測試效果!
- 測試,啟動服務提供者及服務消費者
- 使用openfeign的工廠模式fallbackFactory來實作服務降級
-
- 編寫屬性fallbackFactory配置的類,并實作接口FallbackFactory 《T》
- 在@FeignClient中配置fallbackFacroty屬性=FallbackFactoryConfig .class
- 同樣,編寫類FallbackFactoryConfigImpl實作@FeignClient注解的接口
- 在FallbackFactoryConfig中實作工廠接口FallbackFactory的方法 create
- 測試,浏覽器通路:[http://localhost:8083/another/consumer](http://localhost:8083/another/consumer)
- 另外一種方式擷取異常資訊,其他的沒有變化,隻是直接将方法的實作寫在FallbackFactoryConfig裡面
使用openfeign調用服務(不含sentinel)
代碼
application.properties
server.port=8083
spring.application.name=nacos-consumer02
spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
spring.cloud.nacos.discovery.enabled=true
spring.cloud.nacos.username=nacos
spring.cloud.nacos.password=nacos
#feign.sentinel.enabled=true
#開啟熱部署
#spring.devtools.restart.enabled=true
主啟動類
package com.xl.projects;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.openfeign.EnableFeignClients;
@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
public class NacosConsumer02Application {
public static void main(String[] args) {
SpringApplication.run(NacosConsumer02Application.class, args);
}
}
Controller
package com.xl.projects.controller;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import com.xl.projects.feign.Consumer02Feign;
@RestController
public class Consumer02Controller {
@Resource
private Consumer02Feign consumer02Feign;
@GetMapping("/another/consumer")
public String testInvoke() {
return consumer02Feign.invokeProvider("oooh!~~~,this is another consumer,named consumer02");
}
}
@FeignClient注解的接口
package com.xl.projects.feign;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient(name = "nacos-provider",fallback = FeignFallbackImpl.class)
public interface Consumer02Feign {
/**
* 注意!!!,這裡需要顯示的指定@RquestParam,否者調用的時候會報錯!
*
* @param param
* @return
*/
@GetMapping("/provider/test")
String invokeProvider(@RequestParam String param);
}
以上代碼為服務調用者(消費者)代碼,以下為服務提供者的Controller代碼,其他部分略:
package com.xl.projects.controller;
import java.util.Date;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
/**
* For Test!!!
* @author xl
*
*/
@RestController
public class TestProviderController {
@Value("${spring.application.name}")
private String appName;
/**
* For Test!
* @param param
* @return
*/
@GetMapping("/provider/test")
public String test(String param) {
// throw new RuntimeException("服務端測試異常!");
return new Date().getSeconds()+
", this is provider return msg: current param="+param;
}
@GetMapping("/test")
public String testParam() {
return appName;
}
}
pom.xml 中需添加spring cloud open feign的依賴:
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.xl.projects</groupId>
<artifactId>xl-springcloud-parent-pom</artifactId>
<version>1.0.0</version>
</parent>
<artifactId>xl-nacos-cunsumer02</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<!-- <dependency> -->
<!-- <groupId>com.alibaba.cloud</groupId> -->
<!-- <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId> -->
<!-- </dependency> -->
<!-- <dependency> -->
<!-- <groupId>org.springframework.boot</groupId> -->
<!-- <artifactId>spring-boot-devtools</artifactId> -->
<!-- <scope>test</scope> -->
<!-- </dependency> -->
</dependencies>
</project>
測試
啟動Nacos, 啟動服務提供者項目以及服務消費者項目。浏覽器通路:
http://localhost:8083/another/consumer :
上圖說明使用openfeign調用成功。
在上面@FeignClient注解的接口代碼中,@FeignClient注解有個屬性fallback!這個fallback是幹什麼用的呢?見官網:
https://docs.spring.io/spring-cloud-openfeign/docs/current/reference/html/#spring-cloud-feign-circuitbreaker
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.
大意翻譯 : 當遇到一個錯誤或者熔斷器處于開放狀态,那麼程式就會執行fallback屬性配置的類!
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.
大意翻譯 : fallback配置的類需要實作@FeignClient配置的接口,并且還的是一個Spring bean (類上需要加上@Component注解!)
根據以上翻譯内容,“當程式遇到錯誤時,就會執行fallback配置的類” ,說明fallback可以充當服務降級的作用,那如何通過fallback來實作服務降級呢?
openfeign內建sentinel實作服務降級
可通過openfeign的注解@FeignClient的屬性fallback結合sentinel實作服務降級!
引入sentinel相關環境
引入依賴
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
application.properties中引入配置(啟用):feign.sentinel.enabled=true
server.port=8083
spring.application.name=nacos-consumer02
spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848
spring.cloud.nacos.discovery.enabled=true
spring.cloud.nacos.username=nacos
spring.cloud.nacos.password=nacos
feign.sentinel.enabled=true
#開啟熱部署
#spring.devtools.restart.enabled=true
編寫@FeignClient注解接口的實作類
package com.xl.projects.feign;
import org.springframework.stereotype.Component;
@Component
public class FeignFallbackImpl implements Consumer02Feign {
@Override
public String invokeProvider(String param) {
return ">>>>>>>>>>>>fallback results>>>>>>>>>>>>";
}
}
在服務提供者中,人為添加異常代碼,以供測試 / 或者不啟動服務提供者,服務消費者找不到服務提供者,也會報錯,同樣能夠達到測試效果!
測試,啟動服務提供者及服務消費者
啟動服務消費者時,控制台報錯,啟動失敗!
Caused by: java.lang.IllegalAccessError: class org.springframework.cloud.openfeign.HystrixTargeter$$EnhancerBySpringCGLIB$$29430b6f cannot access its superclass org.springframework.cloud.openfeign.HystrixTargeter
at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_201]
at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[na:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
at org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:535) ~[spring-core-5.2.15.RELEASE.jar:5.2.15.RELEASE]
... 78 common frames omitted
解決:
删除/取消項目熱部署,但,有個問題是熱部署依賴是在父項目的pom中的,直接屏蔽掉,其他子項目都無法使用熱部署的功能了。是以,需要将熱部署的依賴拷貝到本服務消費的pom中,同時将<scope>改為test。因為這樣會覆寫父pom中的依賴,同時scope為test也不會影響正常的編譯階段和運作階段。
修改後 :
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.xl.projects</groupId>
<artifactId>xl-springcloud-parent-pom</artifactId>
<version>1.0.0</version>
</parent>
<artifactId>xl-nacos-cunsumer02</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
</project>
再次啟動,成功!通路位址 :
http://localhost:8083/another/consumer
驗證成功!
使用openfeign的工廠模式fallbackFactory來實作服務降級
形如:
根據@FeignClient的屬性fallback=xxx.class已經可以達到服務降級的目的了,為什麼還需要fallbackFactory呢??
見官網 :
If one needs access to the cause that made the fallback trigger, one can use the fallbackFactory attribute inside @FeignClient
大意翻譯 : 如果想要擷取到觸發fallback的原因(如:異常資訊等),那麼可以通過配置fallbackFactory來擷取。
編寫屬性fallbackFactory配置的類,并實作接口FallbackFactory 《T》
說明 :
-
FallbackFactory的包為:feign.hystrix.FallbackFactory ; 而非org.springframework.cloud.openfeign.FallbackFactory !
-
泛型 T 為 @FeignClient注解的接口類型,也可以是實作接口的類
package com.xl.projects.feign;
import org.springframework.stereotype.Component;
import feign.hystrix.FallbackFactory;
@Component
public class FallbackFactoryConfig implements FallbackFactory<Consumer02Feign> {
@Override
public Consumer02Feign create(Throwable cause) {
FallbackFactoryConfigImpl fallbackFactoryConfigImpl = new FallbackFactoryConfigImpl();
fallbackFactoryConfigImpl.setThrowable(cause);
return fallbackFactoryConfigImpl;
}
/*
@Override
public FallbackFactoryConfigImpl create(Throwable cause) {
FallbackFactoryConfigImpl fallbackFactoryConfigImpl
= new FallbackFactoryConfigImpl() {
@Override
public String invokeProvider(String param) {
System.out.println("調用了實作工廠");
// TODO Auto-generated method stub
return null;
}
@Override
public String test2() {
// TODO Auto-generated method stub
return super.test2();
}
};
return fallbackFactoryConfigImpl;
}
*/
}
在@FeignClient中配置fallbackFacroty屬性=FallbackFactoryConfig .class
package com.xl.projects.feign;
import org.springframework.cloud.openfeign.FeignClient;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
@FeignClient(name = "nacos-provider",fallbackFactory = FallbackFactoryConfig.class)
public interface Consumer02Feign {
/**
* 注意!!!,這裡需要顯示的指定@RquestParam,否者調用的時候會報錯!
*
* @param param
* @return
*/
@GetMapping("/provider/test")
String invokeProvider(@RequestParam String param);
@GetMapping("/test2")
String test2() ;
}
同樣,編寫類FallbackFactoryConfigImpl實作@FeignClient注解的接口
package com.xl.projects.feign;
public class FallbackFactoryConfigImpl implements Consumer02Feign {
private Throwable throwable;
@Override
public String invokeProvider(String param) {
System.out.println("調用了實作接口 :"+ this.getThrowable().getMessage());
return "調用了實作接口 :"+ this.getThrowable().getMessage();
}
@Override
public String test2() {
// TODO Auto-generated method stub
return null;
}
public Throwable getThrowable() {
return throwable;
}
public void setThrowable(Throwable throwable) {
this.throwable = throwable;
}
}
在FallbackFactoryConfig中實作工廠接口FallbackFactory的方法 create
在抛出異常時,上圖建立的fallbackFactoryConfigImpl對象,會去調用自己對應的方法invokeProvider,同時擷取到對應的異常資訊“cause”。
測試,浏覽器通路:http://localhost:8083/another/consumer
controller
package com.xl.projects.controller;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import com.xl.projects.feign.Consumer02Feign;
@RestController
public class Consumer02Controller {
@Resource
private Consumer02Feign consumer02Feign;
@GetMapping("/another/consumer")
public String testInvoke() {
return consumer02Feign.invokeProvider("oooh!~~~,this is another consumer,named consumer02");
}
}
因為,并沒有啟動服務提供者nacos-provider,是以會抛出該異常,同時通過fallbackFactory的方式擷取到了異常資訊,符合預期!!!
另外一種方式擷取異常資訊,其他的沒有變化,隻是直接将方法的實作寫在FallbackFactoryConfig裡面
package com.xl.projects.feign;
import org.springframework.stereotype.Component;
import feign.hystrix.FallbackFactory;
@Component
public class FallbackFactoryConfig implements FallbackFactory<Consumer02Feign> {
// @Override
// public Consumer02Feign create(Throwable cause) {
// FallbackFactoryConfigImpl fallbackFactoryConfigImpl = new FallbackFactoryConfigImpl();
// fallbackFactoryConfigImpl.setThrowable(cause);
// return fallbackFactoryConfigImpl;
// }
@Override
public FallbackFactoryConfigImpl create(Throwable cause) {
FallbackFactoryConfigImpl fallbackFactoryConfigImpl
= new FallbackFactoryConfigImpl() {
@Override
public String invokeProvider(String param) {
System.out.println("調用了實作工廠");
// TODO Auto-generated method stub
return "調用了實作工廠,異常資訊為: " + cause.getMessage();
}
@Override
public String test2() {
// TODO Auto-generated method stub
return super.test2();
}
};
return fallbackFactoryConfigImpl;
}
}
測試結果:
同樣擷取到了異常資訊,說明FallbackFactoryConfig 中方法invokeProvider覆寫了FallbackFactoryConfigImpl 中的方法的實作!