使用 spring 启动的弹性 4j 回退中的 NoSuchMethodException

Question

我是这种断路器技术的新手。 我试图用 eureka 服务器实现这项技术，但在这个后备方法点上卡住了。

我的 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.10.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.microservice</groupId>
<artifactId>inventory-client</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>inventory-client</name>
<description>Demo microservice project for Spring Boot</description>

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>Hoxton.SR8</spring-cloud.version>
</properties>

<dependencies>
    <!-- <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency> -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>io.github.resilience4j</groupId>
        <artifactId>resilience4j-spring-boot2</artifactId>
        <version>1.3.1</version>
    </dependency>
    <dependency>
        <groupId>io.github.resilience4j</groupId>
        <artifactId>resilience4j-circuitbreaker</artifactId>
        <version>1.3.1</version>
    </dependency>
    

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </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>
</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>
    </dependencies>
</dependencyManagement>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

我的 application.properties

spring.application.name=inventory-client-app
server.port=8081

spring.cloud.circuitbreaker.resilience4j.enabled=false

resilience4j.circuitbreaker.instances.itemTypesBreaker.registerHealthIndicator=true
resilience4j.circuitbreaker.instances.itemTypesBreaker.slidingWindowSize=10
resilience4j.circuitbreaker.instances.itemTypesBreaker.permittedNumberOfCallsInHalfOpenState=3
resilience4j.circuitbreaker.instances.itemTypesBreaker.slidingWindowType=TIME_BASED
resilience4j.circuitbreaker.instances.itemTypesBreaker.minimumNumberOfCalls=20
resilience4j.circuitbreaker.instances.itemTypesBreaker.waitDurationInOpenState=50s
resilience4j.circuitbreaker.instances.itemTypesBreaker.failureRateThreshold=50
resilience4j.circuitbreaker.instances.itemTypesBreaker.eventConsumerBufferSize=10

我的 controller

import io.github.resilience4j.circuitbreaker.annotation.CircuitBreaker;

@RestController
@RequestMapping("/inventory-client")
public class ItemTypeController {

@Autowired
RestTemplate restTemplate;


@GetMapping("/item-types")
@ResponseStatus(HttpStatus.OK)
@CircuitBreaker(name="itemTypesBreaker",fallbackMethod = "itemTypesFallBack")
public List<ItemType> getAllItemTypes(){
    List<ItemType> itemTypeList = (List<ItemType>) restTemplate.getForObject("http://inventory-catalog-app/inventory-catalog/item-types/", ItemType.class);
    return itemTypeList;
}

private String itemTypesFallBack(Throwable t){

    return "Item Catalog is down";
    
}

}

我无法使用回退方法调用此端点，我还缺少什么其他配置？ . 提前致谢。

Answer 1

我找到了解决方案。 回退方法签名应该是这样的。

private List<ItemType> itemTypesFallBack(Throwable t){
    System.out.println("Item Catalog is down");
    return null;

}

Answer 2

因此，回退方法的文档应该放在相同的 class 中，并且必须具有相同的方法签名，只有一个额外的目标异常参数。

如果您尝试从 NumberFormatException 中恢复，则会调用签名为 String fallback(String parameter, IllegalArgumentException exception)} 的方法。

通常，我使用 RuntimeException 额外参数创建回退方法。 在您的情况下，该方法将如下所示：

private List<ItemType> itemTypesFallBack(RuntimeException e){
   ...
}