Spring Cloud Ribbon

Spring Cloud Ribbon

• 客户端负载均衡组件Ribbon 负载均衡就是当client端发送请求得时候会均衡得分发到每个server端

创建spring-cloud-02-ribbon-eureka 就是个服务端 参考前面得copy过来的

创建spring-cloud-02-ribbon-client1 项目

• 引入pom.xml

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

• UserController

@RestControllerpublic class UserController {    @RequestMapping(value = "/getUser", method = {RequestMethod.GET})    public User getUser(@RequestParam("id") String id) {        System.err.println("client1 GET-------------" + id);        return new User(id, "20", "张三");    }}

• application.properties

spring.application.name=client-serviceserver.port=1003server.context-path=/eureka.client.service-url.defaultZone=http://eureka1:8003/eureka/spring.output.ansi.enabled=always

• copy client1项目一份

创建 spring-cloud-02-ribbon-request

• 引入pom.xml

<dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-ribbon</artifactId></dependency>

• application.properties

spring.application.name=request-serviceserver.context-path=/server.port=1005eureka.client.service-url.defaultZone=http://eureka1:8003/eureka/spring.output.ansi.enabled=always

• 启动所有 request访问http://localhost:1005/get 当请求得次数一样时，会发现分别在client1和client2端会打印出响应得次数，每个都打印出一半

• 这就是负载均衡 Ribbon

在这里在介绍下retry重试机制

spring-cloud-02-ribbon-retry

• pom.xml

<dependency>    <groupId>org.springframework.cloud</groupId>    <artifactId>spring-cloud-starter-eureka</artifactId></dependency><dependency>    <groupId>org.springframework.cloud</groupId>    <artifactId>spring-cloud-starter-ribbon</artifactId></dependency><dependency>    <groupId>org.springframework.cloud</groupId>    <artifactId>spring-cloud-starter-hystrix</artifactId></dependency><dependency>    <groupId>org.springframework.retry</groupId>    <artifactId>spring-retry</artifactId></dependency>

• application.properties配置

spring.application.name=retry-serviceserver.context-path=/server.port=1006eureka.client.service-url.defaultZone=http://eureka1:8003/eureka/#启动重试机制spring.cloud.loadbalancer.retry.enabled=true ##断路器hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds=14000##连接超时时间#client-service.ribbon.ConnectTimeout=1000##处理超时时间#client-service.ribbon.ReadTimeout=1000req.fact.connect-timeout=1000 req.fact.connection-request-timeout=1000req.fact.read-timeout=3000#是否对所有请求都进行重试client-service.ribbon.OKToRetryOnAllOperations=true#重试切换实例得次数client-service.ribbon.MaxAutoRetriesNextServer=1#重试切次数client-service.ribbon.MaxAutoRetries=5

• 注意：

client-service.ribbon.ConnectTimeout=1000client-service.ribbon.ReadTimeout=1000这样配置没起作用  建议使用RestTemplate原始配置hystrix.command.default.execution.isolation.thread.timeoutInMilliseconds：断路器得超时时间需要大于ribbon得超时时间，不然不会发生重试。

• RetryApplication类

@EnableCircuitBreaker //开启断路器@EnableRetry    //启动Retry框架重试机制@EnableDiscoveryClient //我是服务 注册到服务中心上@SpringBootApplicationpublic class RetryApplication {    @Bean    @ConfigurationProperties(prefix = "req.fact")    public HttpComponentsClientHttpRequestFactory httpComponentsClientHttpRequestFactory(){        return new HttpComponentsClientHttpRequestFactory();    }    @Bean    @LoadBalanced    public RestTemplate restTemplate(){        return new RestTemplate(httpComponentsClientHttpRequestFactory());    }    public static void main(String[] args) {        SpringApplication.run(RetryApplication.class, args);    }}

• IndexController类

@RestControllerpublic class IndexController {    @Autowired    RestTemplate restTemplate;    @RequestMapping(value = "/retry", method = {RequestMethod.GET})    @HystrixCommand(fallbackMethod = "retryFailback")    public String retry(){        ResponseEntity<String> response = restTemplate.getForEntity("http://client-service/retry", String.class);        System.err.println("body:" + response.getBody());        return "----- retry ok -----";    }    public String retryFailback(){        System.err.println("-----启动降级策略----");        return "-----启动降级策略----";    }}

• 在spring-cloud-02-ribbon-client1项目得Controller中添加

 @RequestMapping(value = "/retry", method = {RequestMethod.GET})    public String retry() {        System.err.println("client1  1 call-------------");        try {            Thread.sleep(4000);        } catch (InterruptedException e) {            e.printStackTrace();        }        return "client 1";    }

• 在spring-cloud-02-ribbon-client2项目得Controller中添加

 @RequestMapping(value = "/retry", method = {RequestMethod.GET})    public String retry() {        System.err.println("client1  2 call-------------");        return "client 2";    }

• 在启动http://localhost:1006/retry时，通过Ribbon负载均衡会访问client1或者client2项目得retry方法，当访问到client1得retry方法时，配置得读取超时时间为3ms，重试次数为5次，retry方法睡眠为4ms，就是每次访问retry方法时重试，当重试次数6次后，会采用降级策略，因为熔断器配置得为14ms，超过熔断器得时间就会采用降级策略。
• GitHub地址
• hystrix 先入个门
• 下节服务容错保护组件Hystix