Spring Cloud学习--hystrix断路器服务容错保护

清疚 2022-05-25 20:15 216阅读 0赞

在Spring Cloud Hystrix中实现了线程隔离、断路器等一系列的服务保护功能，它也是基于Netflix的开源框架 Hystrix实现的，该框架目标在于通过控制那些访问远程系统、服务和第三方库的节点，从而对延迟和故障提供更强大的容错能力。Hystrix具备了服务降级、服务熔断、线程隔离、请求缓存、请求合并以及服务监控等强大功能。

接下来我们通过简单的demo示例代码来学习一下spring cloud hystrix相关的知识。

1、pom.xml中引入hystrix断路器相关jar

<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">
    	<parent>
    	    <groupId>org.springframework.boot</groupId>
    	    <artifactId>spring-boot-starter-parent</artifactId>
    	    <version>1.5.10.RELEASE</version>
    	</parent>
    	
    	<dependencyManagement>
    	    <dependencies>
    	        <dependency>
    	            <groupId>org.springframework.cloud</groupId>
    	            <artifactId>spring-cloud-dependencies</artifactId>
    	            <version>Edgware.SR3</version>
    	            <type>pom</type>
    	            <scope>import</scope>
    	        </dependency>
    	    </dependencies>
    	</dependencyManagement>
    	<modelVersion>4.0.0</modelVersion>
    	<groupId>com.tianjunwei</groupId>
    	<artifactId>TJWspringCloud-consumer-hystrix</artifactId>
    	<version>1.0.0-SNAPSHOT</version>
    	<packaging>jar</packaging>
    	<name>TJWspringCloud-consumer</name>
    	<dependencies>
    	    <dependency>
    	        <groupId>org.springframework.cloud</groupId>
    	        <artifactId>spring-cloud-starter-hystrix</artifactId>
    	    </dependency>
    	    <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-eureka</artifactId>
            </dependency>
            <dependency>  
                <groupId>ch.qos.logback</groupId>  
                <artifactId>logback-core</artifactId>  
            </dependency>  
            <dependency>  
                <groupId>ch.qos.logback</groupId>  
                <artifactId>logback-classic</artifactId>  
            </dependency>  
            <dependency>  
                <groupId>ch.qos.logback</groupId>  
                <artifactId>logback-access</artifactId>  
            </dependency>  
    	</dependencies>
    	<build>
    		<resources>
    			<resource>
    				<directory>src/main/java</directory>
    				<includes>
    					<include>**/*.xml</include>
    				</includes>
    			</resource>
    			<resource>
    				<directory>src/test/java</directory>
    				<includes>
    					<include>**/*.xml</include>
    				</includes>
    			</resource>
    			<resource>
    				<directory>src/main/resources</directory>
    				<includes>
    					<include>**/*.*</include>
    				</includes>
    			</resource>
    		</resources>
    		<plugins>  
    			<plugin>
    				<groupId>org.springframework.boot</groupId>
    				<artifactId>spring-boot-maven-plugin</artifactId>
    			</plugin>
    			
    	        <plugin>  
    	            <groupId>org.apache.maven.plugins</groupId>  
    	            <artifactId>maven-compiler-plugin</artifactId>  
    	            <version>2.0.2</version>  
    	            <configuration>  
    	                <source>1.8</source>  
    	                <target>1.8</target>  
    	            </configuration>  
    	        </plugin>  
    	    </plugins>  
    	</build>
    </project>

2、在代码中添加注解@EnableCircuitBreaker表示启用hystrix断路器，通过注解 @HystrixCommand(fallbackMethod = "failback")表示产生异常时调用failback方法

代码示例：

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
    import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
    import org.springframework.cloud.client.loadbalancer.LoadBalanced;
    import org.springframework.cloud.netflix.feign.EnableFeignClients;
    import org.springframework.context.annotation.Bean;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.client.RestTemplate;
    
    import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
    
    @EnableCircuitBreaker
    @EnableFeignClients
    @SpringBootApplication
    @EnableDiscoveryClient
    @RestController
    public class ConsumerApplication {
    	
    	
    	@Bean
        @LoadBalanced
        public RestTemplate restTemplate() {
            return new RestTemplate();
        }
    
    	
        @Autowired
        RestTemplate restTemplate;
    
        @HystrixCommand(fallbackMethod = "failback")
        @RequestMapping(value = "/add", method = RequestMethod.GET)
        public String add() {
            return restTemplate.getForEntity("http://computer-service/add?a=10&b=20", String.class).getBody();
        }
        
        public String failback() {
            return "client failback";
        }
    
        @RequestMapping(value = "/info", method = RequestMethod.GET)
        public String info() {
            return "success";
        }
    	
    	
    	public static void main(String[] args) {
    		SpringApplication.run(ConsumerApplication.class, args);
    	}
    }

当调用http://localhost:2011/add接口，服务提供者不在线时会调用failback方法，返回client failback字符串

![70][]

Spring Cloud Hystrix提供了一个dashboard页面，需要添加相关的jar及相关注解@EnableHystrixDashboard，在pom.xml中添加hystrix dashboard相关的jar

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

重新启动工程访问地址：http://localhost:2011/hystrix

![70 1][]

[70]: /images/20220526/64db26b58a4a4743b1c6f3b64f4e85b0.png
[70 1]: /images/20220526/ab58b3855d3e4d2eba0bdf65bd01af32.png