spring cloud (四) 请求熔断 feign

1 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>Spring-Cloud-Feign</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>Spring-Cloud-Feign</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</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-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix-dashboard</artifactId>
        </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>

</project>

2 配置文件

spring.application.name=feign-consumer
server.port=4001
eureka.client.serviceUrl.defaultZone=http://localhost:8080/eureka/

3 启动类

@EnableFeignClients

@EnableFeignClients
@SpringCloudApplication
public class SpringCloudFeignApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringCloudFeignApplication.class, args);
    }
}

4 根据服务名称来指定服务提供方

//根据服务名称来指定服务提供方
@FeignClient(name="service-a",fallback=TestServiceAFallBack.class)
public interface TestServiceA {
    // 通过注解指定访问方式，访问路径，访问参数
    @RequestMapping(method = RequestMethod.GET, value = "/getm")
    String getMessage(@RequestParam("message") String message);

}

5 回退类 当service-a  getm不可访问是 会返回已经写好的信息

@Component
public class TestServiceAFallBack implements TestServiceA{

    @Override
    public String getMessage(String message) {
        // TODO Auto-generated method stub
        return "the server is error";
    }
}

6 编写测试类

@RestController
public class TestController {
    @Autowired
    TestServiceA testServiceA;

    @GetMapping("/test")
    public String test(String message) {
        return testServiceA.getMessage(message);
    }

}

7 测试

启动 eureka注册中心  service-a  和feign三个项目

访问  http://127.0.0.1:4001/test?message=123 返回  hello world:123

把服务service-a停掉 再次访问  http://127.0.0.1:4001/test?message=123

返回

the server is error