Spring Cloud框架（原生Hoxton版本与Spring Cloud Alibaba）初级篇 ---- 服务调用

逃离我推掉我的手 2023-10-04 19:57 30阅读 0赞

#### 目录 ####

*  一、Ribbon负载均衡服务调用
 *   *  概述
     *  Ribbon负载均衡演示
     *   *  RestTemplate
     *  Ribbon核心组件IRule
     *  Ribbon负载均衡算法
     *   *  原理（RoundRobinRule原理）
         *  源码（RoundRobinRule）
         *  手写负载算法
 *  二、OpenFeign服务接口调用
 *   *  概述
     *  使用步骤
     *  OpenFeign超时控制
     *  OpenFeign日志打印功能

## 一、Ribbon负载均衡服务调用 ##

### 概述 ###

![在这里插入图片描述][e322ee0cc3314e2d89f5cb0d92864630.png]

![在这里插入图片描述][b77d1675df864cada6b95de4b516db0d.png]

![在这里插入图片描述][35cf0e74eab047008cbe160aea01cb6e.png]  
![在这里插入图片描述][784661fee1054dd2996afdaba60a092c.png]  
![在这里插入图片描述][4bd93f5f2bb24b83afe0263616ac50c0.png]

### Ribbon负载均衡演示 ###

Ribbon是客户端（消费者）负载均衡的工具。

![在这里插入图片描述][4415dcb87eef452fb0534f68e6e5fa38.png]  
![在这里插入图片描述][adf1dbc112ed4ee8877ce0906cc28753.png]  
![在这里插入图片描述][222ab6ccf4e04941a37860cedac2d9cd.png]  
Ribbon的POM

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

升级最新版本，eureka自带Ribbon的依赖

![在这里插入图片描述][ed8eae849ca8417288222e59960a3753.png]

#### RestTemplate ####

**@LoadBalanced**注解给RestTemplate开启负载均衡的能力。

官方文档：[https://docs.spring.io/spring-framework/docs/5.2.2.RELEASE/javadoc-api/org/springframework/web/client/RestTemplate.html][https_docs.spring.io_spring-framework_docs_5.2.2.RELEASE_javadoc-api_org_springframework_web_client_RestTemplate.html]

**getForObject/getForEntity方法**

![dfd1d2fb34744845946c21c50af53ccb.png][]  
**测试getForEntity方法**

@GetMapping("/consumer/payment/getForEntity/{id}")
        public CommonResult<Payment> getPayment2(@PathVariable("id") Long id){
        
            ResponseEntity<CommonResult> entity = restTemplate.getForEntity(PAYMENT_URL + "/payment/get/" + id, CommonResult.class);
            if (entity.getStatusCode().is2xxSuccessful()){
        
                return entity.getBody();
            }else {
        
                return new CommonResult<>(444,"操作失败");
            }
        }

重启测试

![在这里插入图片描述][88c3025bed7e4266b5db4e995dd17cce.png]

### Ribbon核心组件IRule ###

IRule:根据特定的算法从服务列表中选取一个要访问的服务。  
IRule接口的实现：

![在这里插入图片描述][190900534ee54bc590a016ae3148ec65.png]

负载均衡常用规则：默认为RoundRobinRule轮询。

![在这里插入图片描述][0097d7bccce24c528aaab57a3e8c5004.png]  
**替换规则**

![在这里插入图片描述][a01d59918fa441c1bc66b41b89950609.png]  
**Ribbon的自定义配置类不可以放在@ComponentScan所扫描的当前包下以及子包下，否则这个自定义配置类就会被所有的Ribbon客户端共享，达不到为指定的Ribbon定制配置，而@SpringBootApplication注解里就有@ComponentScan注解，所以不可以放在主启动类所在的包下。（因为Ribbon是客户端（消费者）这边的，所以Ribbon的自定义配置类是在客户端（消费者）添加，不需要在提供者或注册中心添加）**

1.  重新创建项目包  
    ![在这里插入图片描述][3d5bafe4fd354a009e39dbcbf04907a6.png]
2.  创建MySelfRule规则类

@Configuration
    public class MySelfRule {
        
        
        @Bean
        public IRule myRule(){
        
        	// 随机
            return new RandomRule();
        }
    }

1.  主启动添加`@RibbonClient(name = "CLOUD-PAYMENT-SERVICE", configuration = MySelfRule.class)`，告诉服务用那种负载模式

@SpringBootApplication
    @EnableEurekaClient
    @RibbonClient(name = "CLOUD-PAYMENT-SERVICE", configuration = MySelfRule.class)
    public class OrderMain80 {
        
        public static void main(String[] args) {
        
            SpringApplication.run(OrderMain80.class);
        }
    }

1.  启动测试，浏览器输入`http://localhost/consumer/payment/get/1`，多次刷新实现负载均衡为随机。

### Ribbon负载均衡算法 ###

#### 原理（RoundRobinRule原理） ####

![在这里插入图片描述][372b7b68b97c4fd3a7ecf7b49f494b02.png]

#### 源码（RoundRobinRule） ####

public Server choose(ILoadBalancer lb, Object key) {
        
            if (lb == null) {
        
                log.warn("no load balancer");
                return null;
            }
    
            Server server = null;
            int count = 0;
            while (server == null && count++ < 10) {
        
                List<Server> reachableServers = lb.getReachableServers();
                List<Server> allServers = lb.getAllServers();
                int upCount = reachableServers.size();
                int serverCount = allServers.size();
    
                if ((upCount == 0) || (serverCount == 0)) {
        
                    log.warn("No up servers available from load balancer: " + lb);
                    return null;
                }
    
                int nextServerIndex = incrementAndGetModulo(serverCount);
                server = allServers.get(nextServerIndex);
    
                if (server == null) {
        
                    /* Transient. */
                    Thread.yield();
                    continue;
                }
    
                if (server.isAlive() && (server.isReadyToServe())) {
        
                    return (server);
                }
    
                // Next.
                server = null;
            }
    
            if (count >= 10) {
        
                log.warn("No available alive servers after 10 tries from load balancer: "
                        + lb);
            }
            return server;
        }
    
        /**
         * Inspired by the implementation of {@link AtomicInteger#incrementAndGet()}.
         *
         * @param modulo The modulo to bound the value of the counter.
         * @return The next value.
         */
        private int incrementAndGetModulo(int modulo) {
        
            for (;;) {
        
                int current = nextServerCyclicCounter.get();
                int next = (current + 1) % modulo;
                if (nextServerCyclicCounter.compareAndSet(current, next))
                    return next;
            }
        }

#### 手写负载算法 ####

1.  启动7001、7002 eureka集群
2.  修改8001、8002的controller

@GetMapping(value = "/payment/lb")
        public String getPaymentLB(){
        
            return serverPort;
        }

3.80订单微服务改造

*  去掉ApplicationContextConfig里restTemplate方法上的@LoadBalanced注解。
 *  在springcloud包下新建lb.ILoadBalancer接口（自定义负载均衡机制（面向接口））

public interface ILoadBalancer {
        
        //传入具体实例的集合，返回选中的实例
        ServiceInstance instance(List<ServiceInstance> serviceInstances);
    }

*  在lb包下新建自定义ILoadBalancer接口的实现类

@Component
    public class MyLB implements LoadBalancer {
        
    
        private AtomicInteger atomicInteger = new AtomicInteger(0);
    
        public final int getAndIncrement() {
        
            int current;
            int next;
            // 自旋锁
            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;
        }
    
        @Override
        public ServiceInstance instance(List<ServiceInstance> serviceInstances) {
        
            int index = getAndIncrement() % serviceInstances.size();
    
            return serviceInstances.get(index);
        }
    }

*  修改controller

@Resource
        private RestTemplate restTemplate;
    
        @Resource
        private LoadBalancer loadBalancer;
        
        @GetMapping("/consumer/payment/lb")
        public String getPaymentLB() {
        
            List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
            if (instances == null || instances.size() <= 0){
        
                return null;
            }
            ServiceInstance serviceInstance = loadBalancer.instance(instances);
            URI uri = serviceInstance.getUri();
            return  restTemplate.getForObject(uri+"/payment/lb",String.class);
        }

## 二、OpenFeign服务接口调用 ##

### 概述 ###

官网文档：[https://cloud.spring.io/spring-cloud-static/Hoxton.SR1/reference/htmlsingle/\#spring-cloud-openfeign][https_cloud.spring.io_spring-cloud-static_Hoxton.SR1_reference_htmlsingle_spring-cloud-openfeign]

![在这里插入图片描述][1fdaa64d1c714da6a0701f4a57de0fc5.png]  
**Feign是一个声明式的web服务客户端，让编写web服务客户端变得非常容易，只需创建一个接口并在接口上添加注解即可。**

![在这里插入图片描述][6f74c910c0ca43f984404beafce2be3c.png]

**OpenFeign和Feign的区别**

![在这里插入图片描述][04ace82806f842b99d8e769a9e525e65.png]  
**OpenFeign使用在客户端（消费测）**  
![在这里插入图片描述][e7942b78ca53458f8898000dedada7f7.png]

### 使用步骤 ###

1.  新建模块  
    ![在这里插入图片描述][9345c86c7a6b480a8a25cf00d01d5c7a.png]
2.  改POM

<dependencies>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-openfeign</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
            </dependency>
            
            <dependency>
                <groupId>com.zhao.springcloud</groupId>
                <artifactId>cloud-api-commons</artifactId>
                <version>1.0-SNAPSHOT</version>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-web</artifactId>
            </dependency>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-actuator</artifactId>
            </dependency>
            
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-devtools</artifactId>
                <scope>runtime</scope>
                <optional>true</optional>
            </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>
            </dependency>
        </dependencies>

1.  写YML

server:
      port: 80 
    
    eureka:
      client:
        register-with-eureka: false
        service-url:
          defaultZone: http://eureka7001.com:7001/eureka,http://eureka7002.com:7002/eureka,http://eureka7003.com:7003/eureka

1.  主启动类

@SpringBootApplication
    // 激活开启feign
    @EnableFeignClients
    public class OrderFeign {
        
        public static void main(String[] args) {
        
            SpringApplication.run(OrderFeign.class);
        }
    }

1.  业务类

@Component
    @FeignClient(value = "CLOUD-PAYMENT-SERVICE")
    public interface PaymentFeignService {
        
    
        @GetMapping("/payment/get/{id}")
        public CommonResult getPaymentById(@PathVariable("id") Long id);
    }

1.  编写controller

@RestController
    @Slf4j
    public class OrderFeignController {
        
        @Resource
        private PaymentFeignService paymentFeignService;
        @GetMapping("/consumer/payment/get/{id}")
        public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id){
        
            return paymentFeignService.getPaymentById(id);
        }
    }

7.启动测试  
**自带负载均衡功能**  
![在这里插入图片描述][916afafb750441ed9367d15190344e7c.png]  
![在这里插入图片描述][2eefcf68d70146d0ad8fb893dfb43827.png]  
![在这里插入图片描述][e9349f9e934340ae9fb34d4ad46c3860.png]

### OpenFeign超时控制 ###

**提供者在处理服务时用了3秒，提供者认为花3秒是正常，而消费者只愿意等1秒，1秒后，提供者会没返回数据，消费者就会造成超时调用报错。所以需要双方约定好时间，不使用默认的。**

模拟超时出错的情况

![在这里插入图片描述][11a573c7f6b54da1bdb7f841699dc199.png]

1.  在8001的PaymentController里添加：（模拟服务处理时间长）

@GetMapping("/payment/feign/timeout")
        public String paymentFeignTimeout(){
        
            try{
        
                TimeUnit.SECONDS.sleep(3);
            }catch (InterruptedException e){
        
                e.printStackTrace();
            }
            return serverPort;
        }

1.  在80的PaymentFeignService中添加：

@GetMapping("/payment/feign/timeout")
        public String paymentFeignTimeout();

1.  然后在80的OrderFeignController中添加：

@GetMapping("/consumer/payment/feign/timeout")
        public String paymentFeignTimeout(){
        
            //openFeign-ribbon，客户端一般默认等待1秒
            return paymentFeignService.paymentFeignTimeout();
        }

1.  测试  
    ![在这里插入图片描述][ef9b18174604462897211f503907b436.png]  
    ![在这里插入图片描述][e341578517924d75974dda58c06758b6.png]
2.  YML开启超时时间

#没提示不管它，可以设置
    ribbon:
      #指的是建立连接后从服务器读取到可用资源所用的时间
      ReadTimeout: 5000
      #指的是建立连接使用的时间，适用于网络状况正常的情况下，两端连接所用的时间
      ConnectTimeout: 5000

1.  重新测试  
    ![在这里插入图片描述][1f728b06958e44daa344a4801f4ae10f.png]

### OpenFeign日志打印功能 ###

概述

![在这里插入图片描述][e0dc68c342f44fdab7b112fc84490cf4.png]  
打印级别

![在这里插入图片描述][0b83ac8d8cd64adf9ec9e93ec99cc317.png]  
设置步骤

*  配置日志bean

@Configuration
    public class FeignConfig {
        
        @Bean
        Logger.Level feignLogLevel(){
        
            return Logger.Level.FULL;
        }
    }

*  Yml中开启日志

logging:
      level:
      #feign日志以什么级别监控哪个接口
        com.zhao.springcloud.service.PaymentFeignService: debug

*  测试  
    ![在这里插入图片描述][96db966912cd46f994d2ba49c54ce8fb.png]  
    ![在这里插入图片描述][f9207a42d2ac4c6a891b63db8d95532d.png]

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