SpringCloud中怎么使用Ribbon和RestTemplate实现服务调用和负载平衡

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SpringCloud 是目前微服务架构领域的翘楚，备受开发者和企业的青睐。

文件目录结构

文件目录结构很重要，特别注意的是rule文件要放在主启动类上一级位置，才能够扫描。

写pom

                            org.springframework.boot            spring-boot-starter-web                                    org.springframework.boot            spring-boot-starter-actuator                                    org.projectlombok            lombok            true                            org.springframework.boot            spring-boot-starter-test            test                                    org.springframework.cloud            spring-cloud-starter-netflix-eureka-client        

因为eureka的依赖已经整合了ribbon的依赖，所以不用额外引入新的东西。

改yml

server:  port: 80spring:  application:    name: cloud-book-consumereureka:  client:    register-with-eureka: false    fetch-registry: true    service-url:      defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka

主启动

@SpringBootApplication@EnableEurekaClient@RibbonClient(name = "CLOUD-BOOK-SERVICE", configuration = LoadBalanceRule.class)   //更换轮询算法public class RestTemplateMain80 {    public static void main(String[] args) {        SpringApplication.run(RestTemplateMain80.class,args);    }}

业务逻辑

rules层

在图示文件目录下新建LoadBalanceRule.class，用于更换负载均衡算法。

@Configurationpublic class LoadBalanceRule {    @Bean    public IRule iRule() {        // 定义为随机        return new RandomRule();    }}

config层

开启restTemplate负载均衡
在config文件夹下创建LoadBalanceConfig.class

@Configurationpublic class LoadBalanceConfig {    @Bean    @LoadBalanced            //开启负载均衡    public RestTemplate getReatTemplate(){        return new RestTemplate();    }}

controller层

新建BookController.class
写业务代码

@RestController@Slf4jpublic class BookController {    @Resource    private RestTemplate restTemplate;    public static final String PAYMENT_URL = "http://CLOUD-BOOK-SERVICE";    @GetMapping(value = "restTemplate/book/getAllBooks")//只要json数据时    public CommonResult getAllBooks(){        return restTemplate.getForObject(PAYMENT_URL+"/book/getAllBooks",CommonResult.class);    }    @GetMapping("restTemplate/book/getAllBooks2")    //需要知道更多数据时，使用getForEntity方法    public CommonResult getAllBooks2(){        ResponseEntity resultResponseEntit = restTemplate.getForEntity(PAYMENT_URL+"/book/getAllBooks",CommonResult.class);        if (resultResponseEntit.getStatusCode().is2xxSuccessful()){            log.info(resultResponseEntit.getStatusCode()+"     "+resultResponseEntit.getHeaders());            return resultResponseEntit.getBody();        }else {            return new CommonResult<>(444,"操作失败");        }    }    @GetMapping(value = "restTemplate/book/index")    public String index() {        return restTemplate.getForObject(PAYMENT_URL+"/book/index",String.class);    }}

使用restTemplate+Ribboin实现服务调用和负载均衡完成。

手写Ribbon负载均衡算法 lb层

1.新建LoadBalancer接口，添加代码

public interface LoadBalancer {    ServiceInstance instances(List serviceInstances);}

2.新建实现类MyLB

@Componentpublic class MyLB implements LoadBalancer {    private AtomicInteger atomicInteger = new AtomicInteger(0);    //求第几次访问  自旋锁思想    public final int getAndIncrement(){        int current;        int next;        do {            current = this.atomicInteger.get();            next = current >=2147483647 ? 0 : current+1;        }while(!this.atomicInteger.compareAndSet(current,next));        System.out.println("***第几次访问next->"+next);        return next;    }    //负载均衡算法,实现roundRobin算法    @Override    public ServiceInstance instances(List serviceInstances) {        int index = getAndIncrement() % serviceInstances.size();        return serviceInstances.get(index);    }}

修改BookController

@RestController@Slf4jpublic class BookController {    @Resource    private RestTemplate restTemplate;    @Resource    private LoadBalancer loadBalancer;    @Resource    private DiscoveryClient discoveryClient;    public static final String PAYMENT_URL = "http://CLOUD-BOOK-SERVICE";    @GetMapping(value = "restTemplate/book/getAllBooks")//只要json数据时    public CommonResult getAllBooks(){        List instances = discoveryClient.getInstances("CLOUD-BOOK-SERVICE");        if (instances == null || instances.size() <= 0){            return null;        }        ServiceInstance serviceInstance = loadBalancer.instances(instances);        URI uri = serviceInstance.getUri();        return restTemplate.getForObject(uri+"/book/getAllBooks",CommonResult.class);    }    @GetMapping(value = "restTemplate/book/index")    public String index() {        List instances = discoveryClient.getInstances("CLOUD-BOOK-SERVICE");        if (instances == null || instances.size() <= 0){            return null;        }        ServiceInstance serviceInstance = loadBalancer.instances(instances);        URI uri = serviceInstance.getUri();        return restTemplate.getForObject(uri+"/book/index",String.class);    }}

修改文件注解

• 删去主启动类的更换负载均衡算法注解

@RibbonClient(name = "CLOUD-BOOK-SERVICE", configuration = LoadBalanceRule.class)

• 删去LoadBalanceConfig中开启负载均衡算法注解

@LoadBalanced

手写Ribbon算法并使用完成

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