标签:temp eager rand reload protect prope 自带 enabled bsp
经过以上的学习,已经实现了服务的注册和服务发现。当启动某个服务的时候,可以通过HTTP的形式将信息注册到注册中心,并且可以通过SpringCloud提供的工具获取注册中心的服务列表。但是服务之间的调用还存在很多的问题,如何更加方便的调用微服务,多个微服务的提供者如何选择,如何负载均衡等
是 Netflixfa 发布的一个负载均衡器,有助于控制 HTTP 和 TCP客户端行为。在 SpringCloud 中,Eureka一般配合Ribbon进行使用,Ribbon提供了客户端负载均衡的功能,Ribbon利用从Eureka中读取到的服务信息,在调用服务节点提供的服务时,会合理的进行负载。
在SpringCloud中可以将注册中心和Ribbon配合使用,Ribbon自动的从注册中心中获取服务提供者的列表信息,并基于内置的负载均衡算法,请求服务。
架构说明:
Ribbon在工作时分成两步
第一步先选择 EurekaServer ,它优先选择在同一个区域内负载较少的server.
第二步再根据用户指定的策略,在从server取到的服务注册列表中选择一个地址。
其中Ribbon提供了多种策略:比如轮询、随机和根据响应时间加权
(1)服务调用
基于Ribbon实现服务调用, 是通过拉取到的所有服务列表组成(服务名-请求路径的)映射关系。借助RestTemplate 最终进行调用。
(2)负载均衡
当有多个服务提供者时,Ribbon可以根据负载均衡的算法自动的选择需要调用的服务地址
之前写样例时候没有引入spring-cloud-starter-ribbon也可以使用ribbon
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-ribbon</artifactId>
</dependency>
猜测spring-cloud-starter-netflix-eureka-client自带了spring-cloud-starter-ribbon引用
证明如下: 可以看到spring-cloud-starter-netflix-eureka-client 确实引入了Ribbon
服务提供者
cloud-provider-payment-8001
cloud-provider-payment-8002
pom
<!--eureka-client-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</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.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
</dependency>
主启动类
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@MapperScan(basePackages = "com.mine.springcloud.payment.dao")
public class PaymentApplication8001 {
public static void main(String[] args) {
SpringApplication.run(PaymentApplication8001.class, args);
}
}
Controller
@RestController
@Slf4j
public class PaymentController {
@Resource
private PaymentService paymentService;
@Resource
private DiscoveryClient discoveryClient;
@Value(value = "${server.port}")
private Integer serverPort;
@PostMapping(value = "/payment/create")
public CommonResult create(@RequestBody Payment payment) {
int result = paymentService.create(payment);
log.info("*****插入操作返回结果:" + result);
if (result > 0) {
return CommonResult.init(200, "create success");
} else {
return CommonResult.init(500, "create fials");
}
}
@GetMapping(value = "payment/get/{id}")
public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id) {
Payment payment = paymentService.getPaymentById(id);
log.info("*****查询结果:{}", payment);
if (payment != null) {
return CommonResult.init(200, "get success serverPort:" + serverPort, payment);
} else {
return CommonResult.init(404, "get null");
}
}
}
服务消费者
cloud-consumer-order-80
pom
<!--eureka-client-->
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</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>
主启动类
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
public class OrderApplication {
public static void main(String[] args) {
SpringApplication.run(OrderApplication.class, args);
}
}
Controller
@RestController
@Slf4j
public class OrderController {
//private String PAYMENT_URL = "http://localhost:8001/";
private String PAYMENT_SERVICE_URL = "http://CLOUD-PAYMENT-SERVICE";
@Resource
private RestTemplate restTemplate;
@Resource
private DiscoveryClient discoveryClient;
@PostMapping(value = "/consumer/payment/create")
public CommonResult create(Payment payment) {
return restTemplate.postForObject(PAYMENT_SERVICE_URL + "/payment/create", payment, CommonResult.class);
}
@GetMapping(value = "/consumer/payment/get/{id}")
public CommonResult<Payment> getPaymentById(@PathVariable("id") Long id) {
return restTemplate.getForObject(PAYMENT_SERVICE_URL + "/payment/get/" + id, CommonResult.class, id);
}
}
配置Bean
@Configuration
public class ApplicationContextConfig {
@Bean
@LoadBalanced
public RestTemplate restTemplate() {
return new RestTemplate();
}
}
在搭建网站时,如果单节点的 web服务性能和可靠性都无法达到要求;或者是在使用外网服务时,经常担心被人攻破,一不小心就会有打开外网端口的情况,通常这个时候加入负载均衡就能有效解决服务问题
负载均衡是一种基础的网络服务,其原理是通过运行在前面的负载均衡服务,按照指定的负载均衡算法,将流量分配到后端服务集群上,从而为系统提供并行扩展的能力。
负载均衡的应用场景包括流量包、转发规则以及后端服务,由于该服务有内外网个例、健康检查等功能,能够有效提供系统的安全性和可用性。
服务端负载均衡
先发送请求到负载均衡服务器或者软件,然后通过负载均衡算法,在多个服务器之间选择一个进行访问;即在服务器端再进行负载均衡算法分配
客户端负载均衡
客户端会有一个服务器地址列表,在发送请求前通过负载均衡算法选择一个服务器,然后进行访问,这是客户端负载均衡;即在客户端就进行负载均衡算法分配
Ribbon内置了多种负载均衡策略,内部负责复杂均衡的顶级接口为com.netflix.loadbalancer.IRule ,实现方式如下
##需要调用的微服务名称
cloud-order-service:
ribbon:
NFLoadBalancerRuleClassName: com.netflix.loadbalancer.RandomRule
新建包com.mine.springcloud.myrule与主启动类所扫描包区分开
定义负载均衡策略
import com.netflix.loadbalancer.IRule;
import com.netflix.loadbalancer.RandomRule;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class MySelfRule {
@Bean
public IRule myRule() {
return new RandomRule();//定义为随机
}
}
主启动类添加@RibbonClient注解
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
@RibbonClient(name = "CLOUD-PAYMENT-SERVICE", configuration = MySelfRule.class)
public class OrderApplication {
public static void main(String[] args) {
SpringApplication.run(OrderApplication.class, args);
}
}
@Configuration
public class ApplicationContextBean
{
@Bean
//@LoadBalanced
public RestTemplate getRestTemplate()
{
return new RestTemplate();
}
}
@SpringBootApplication
@EnableEurekaClient
@EnableDiscoveryClient
//@RibbonClient(name = "CLOUD-PAYMENT-SERVICE", configuration = MySelfRule.class)
public class OrderApplication {
public static void main(String[] args) {
SpringApplication.run(OrderApplication.class, args);
}
}
package com.mine.springcloud.order.lb;
import org.springframework.cloud.client.ServiceInstance;
import java.util.List;
public interface LoadBalancer {
ServiceInstance instances(List<ServiceInstance> list);
}
package com.mine.springcloud.order.lb;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.stereotype.Component;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
@Component
@Slf4j
public class MyLB implements LoadBalancer {
private AtomicInteger atomicInteger = new AtomicInteger(0);
private Integer getAndIncrement() {
int current;
int next;
do {
current = atomicInteger.get();
next = current >= Integer.MAX_VALUE ? 0 : current + 1;
log.info("next:" + next);
} while (!atomicInteger.compareAndSet(current, next));
return next;
}
@Override
public ServiceInstance instances(List<ServiceInstance> list) {
return list.get(getAndIncrement() % list.size());
}
}
package com.mine.springcloud.order.controller;
import com.mine.springcloud.commons.base.CommonResult;
import com.mine.springcloud.commons.entity.Payment;
import com.mine.springcloud.order.lb.LoadBalancer;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.discovery.DiscoveryClient;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;
import javax.annotation.Resource;
import java.util.List;
@RestController
@Slf4j
public class OrderController {
//private String PAYMENT_URL = "http://localhost:8001/";
private String PAYMENT_SERVICE_URL = "http://CLOUD-PAYMENT-SERVICE";
@Resource
private RestTemplate restTemplate;
@Resource
private LoadBalancer loadBalancer;
@Resource
private DiscoveryClient discoveryClient;
@GetMapping(value = "/consumer/payment/lb")
public CommonResult<Payment> getLB() {
List<ServiceInstance> instances = discoveryClient.getInstances("CLOUD-PAYMENT-SERVICE");
if (instances == null || instances.size() == 0) {
return CommonResult.init(500, "instances is null");
}
ServiceInstance instance = loadBalancer.instances(instances);
return restTemplate.getForObject(instance.getUri() + "/payment/lb", CommonResult.class);
}
}
负载均衡算法:rest接口第几次请求数 % 服务器集群总数量 = 实际调用服务器位置下标 ,每次服务重启动后rest接口计数从1开始。
List
如:
List [0] instances = 127.0.0.1:8002
List [1] instances = 127.0.0.1:8001
8001+ 8002 组合成为集群,它们共计2台机器,集群总数为2, 按照轮询算法原理:
当总请求数为1时: 1 % 2 =1 对应下标位置为1 ,则获得服务地址为127.0.0.1:8001
当总请求数位2时: 2 % 2 =0 对应下标位置为0 ,则获得服务地址为127.0.0.1:8002
当总请求数位3时: 3 % 2 =1 对应下标位置为1 ,则获得服务地址为127.0.0.1:8001
当总请求数位4时: 4 % 2 =0 对应下标位置为0 ,则获得服务地址为127.0.0.1:8002
如此类推......
使用Ribbon完成客户端负载均衡往往是从一个注解开始的
/**
* 基于Ribbon的服务调用与负载均衡
*/
@LoadBalanced
@Bean
public RestTemplate getRestTemplate() {
return new RestTemplate();
}
这个注解的主要作用是什么呢,查看源码
/**
* Annotation to mark a RestTemplate bean to be configured to use a
LoadBalancerClient
* @author Spencer Gibb
*/
@Target({ ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Qualifier
public @interface LoadBalanced {
}
通过注释可以知道@LoadBalanced注解是用来给RestTemplate做标记,方便我们对RestTemplate添加一个LoadBalancerClient,以实现客户端负载均衡。
根据SpringBoot中的自动装配规则可以在 spring-cloud-netflix-ribbon-2.1.0.RELEASE.jar 中可以找到 spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\org.springframew
ork.cloud.netflix.ribbon.RibbonAutoConfiguration
找到自动装配的类RibbonAutoConfiguration
@Configuration
@Conditional({RibbonAutoConfiguration.RibbonClassesConditions.class})
@RibbonClients
@AutoConfigureAfter(name = {"org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration"})
@AutoConfigureBefore({LoadBalancerAutoConfiguration.class,
AsyncLoadBalancerAutoConfiguration.class})
@EnableConfigurationProperties({RibbonEagerLoadProperties.class,
ServerIntrospectorProperties.class})
public class RibbonAutoConfiguration {
@Bean
public SpringClientFactory springClientFactory() {
SpringClientFactory factory = new SpringClientFactory();
factory.setConfigurations(this.configurations);
return factory;
}
@Bean
@ConditionalOnMissingBean({LoadBalancerClient.class})
public LoadBalancerClient loadBalancerClient() {
return new RibbonLoadBalancerClient(this.springClientFactory());
}
//省略
}
通过 RibbonAutoConfiguration 引入了 LoadBalancerAutoConfiguration 配置类
@Configuration
@ConditionalOnClass({RestTemplate.class})
@ConditionalOnBean({LoadBalancerClient.class})
@EnableConfigurationProperties({LoadBalancerRetryProperties.class})
public class LoadBalancerAutoConfiguration {
@LoadBalanced
@Autowired(required = false)
private List<RestTemplate> restTemplates = Collections.emptyList();
@Autowired( required = false)
private List<LoadBalancerRequestTransformer> transformers = Collections.emptyList();
public LoadBalancerAutoConfiguration() {
}
@Bean
public SmartInitializingSingleton
loadBalancedRestTemplateInitializerDeprecated(ObjectProvider<List<RestTemplateCustomizer>> restTemplateCustomizers) {
return () -> {
restTemplateCustomizers.ifAvailable((customizers) -> {
Iterator var2 = this.restTemplates.iterator();
while(var2.hasNext()) {
RestTemplate restTemplate = (RestTemplate)var2.next();
Iterator var4 = customizers.iterator();
while(var4.hasNext()) {
RestTemplateCustomizer customizer =(RestTemplateCustomizer)var4.next();
customizer.customize(restTemplate);
}
}
});
};
}
@Bean
@ConditionalOnMissingBean
public LoadBalancerRequestFactory loadBalancerRequestFactory(LoadBalancerClient loadBalancerClient) {
return new LoadBalancerRequestFactory(loadBalancerClient,this.transformers);
}
@Configuration
@ConditionalOnClass({RetryTemplate.class})
public static class RetryInterceptorAutoConfiguration {
public RetryInterceptorAutoConfiguration() {
}
@Bean
@ConditionalOnMissingBean
public RetryLoadBalancerInterceptor ribbonInterceptor(LoadBalancerClient loadBalancerClient, LoadBalancerRetryProperties properties,LoadBalancerRequestFactory requestFactory, LoadBalancedRetryFactory loadBalancedRetryFactory) {
return new RetryLoadBalancerInterceptor(loadBalancerClient,properties, requestFactory, loadBalancedRetryFactory);
}
@Bean
@ConditionalOnMissingBean
public RestTemplateCustomizer restTemplateCustomizer(RetryLoadBalancerInterceptor loadBalancerInterceptor) {
return (restTemplate) -> {
List<ClientHttpRequestInterceptor> list = new ArrayList(restTemplate.getInterceptors());
list.add(loadBalancerInterceptor);
restTemplate.setInterceptors(list);
};
}
}
@Configuration
@ConditionalOnClass({RetryTemplate.class})
public static class RetryAutoConfiguration {
public RetryAutoConfiguration() {
}
@Bean
@ConditionalOnMissingBean
public LoadBalancedRetryFactory loadBalancedRetryFactory() {
return new LoadBalancedRetryFactory() {
};
}
}
@Configuration
@ConditionalOnMissingClass({"org.springframework.retry.support.RetryTemplate"})
static class LoadBalancerInterceptorConfig {
LoadBalancerInterceptorConfig() {
}
@Bean
public LoadBalancerInterceptor ribbonInterceptor(LoadBalancerClient loadBalancerClient, LoadBalancerRequestFactory requestFactory) {
return new LoadBalancerInterceptor(loadBalancerClient,requestFactory);
}
@Bean
@ConditionalOnMissingBean
public RestTemplateCustomizer restTemplateCustomizer(LoadBalancerInterceptor loadBalancerInterceptor) {
return (restTemplate) -> {
List<ClientHttpRequestInterceptor> list = new ArrayList(restTemplate.getInterceptors());
list.add(loadBalancerInterceptor);
restTemplate.setInterceptors(list);
};
}
}
}
在该自动化配置类中,主要做了下面三件事:
LoadBalancerInterceptor 拦截器。
public class LoadBalancerInterceptor implements ClientHttpRequestInterceptor {
private LoadBalancerClient loadBalancer;
private LoadBalancerRequestFactory requestFactory;
public LoadBalancerInterceptor(LoadBalancerClient loadBalancer, LoadBalancerRequestFactory requestFactory) {
this.loadBalancer = loadBalancer;
this.requestFactory = requestFactory;
}
public LoadBalancerInterceptor(LoadBalancerClient loadBalancer) {
this(loadBalancer, new LoadBalancerRequestFactory(loadBalancer));
}
public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
URI originalUri = request.getURI();
String serviceName = originalUri.getHost();
Assert.state(serviceName != null, "Request URI does not contain a valid hostname: " + originalUri);
return (ClientHttpResponse)this.loadBalancer.execute(serviceName, this.requestFactory.createRequest(request, body, execution));
}
}
通过源码以及之前的自动化配置类,我们可以看到在拦截器中注入了 LoadBalancerClient 的实现。当一个被 @LoadBalanced 注解修饰的 RestTemplate 对象向外发起HTTP请求时,会被LoadBalancerInterceptor 类的 intercept 函数所拦截。由于我们在使用RestTemplate时候采用了服务名作为host,所以直接从 HttpRequest 的URI对象中通过getHost()就可以拿到服务名,然后调用execute 函数去根据服务名来选择实例并发起实际的请求。
分析到这里, LoadBalancerClient 还只是一个抽象的负载均衡器接口,所以我们还需要找到它的具体实现类来进一步分析。通过查看ribbon的源码,我们可以很容易的在org.springframework.cloud.netflix.ribbon 包下找到对应的实现类:RibbonLoadBalancerClient 。
public class RibbonLoadBalancerClient implements LoadBalancerClient {
public ServiceInstance choose(String serviceId) {
Server server = this.getServer(serviceId);
return server == null ? null : new RibbonLoadBalancerClient.RibbonServer(serviceId, server, this.isSecure(server, serviceId), this.serverIntrospector(serviceId).getMetadata(server));
}
public <T> T execute(String serviceId, LoadBalancerRequest<T> request) throws IOException {
ILoadBalancer loadBalancer = this.getLoadBalancer(serviceId);
Server server = this.getServer(loadBalancer);
if (server == null) {
throw new IllegalStateException("No instances available for " + serviceId);
} else {
RibbonLoadBalancerClient.RibbonServer ribbonServer = new RibbonLoadBalancerClient.RibbonServer(serviceId, server, this.isSecure(server, serviceId), this.serverIntrospector(serviceId).getMetadata(server));
return this.execute(serviceId, ribbonServer, request);
}
}
protected Server getServer(String serviceId) {
return this.getServer(this.getLoadBalancer(serviceId));
}
protected Server getServer(ILoadBalancer loadBalancer) {
return loadBalancer == null ? null : loadBalancer.chooseServer("default");
}
protected ILoadBalancer getLoadBalancer(String serviceId) {
return this.clientFactory.getLoadBalancer(serviceId);
}
//省略...
}
从 RibbonLoadBalancerClient 代码可以看出,实际负载均衡的是通过 ILoadBalancer 来实现的
@Bean
@ConditionalOnMissingBean
public ILoadBalancer ribbonLoadBalancer(IClientConfig config, ServerList<Server>serverList, ServerListFilter<Server> serverListFilter, IRule rule, IPing ping,ServerListUpdater serverListUpdater) {
return (ILoadBalancer)(this.propertiesFactory.isSet(ILoadBalancer.class, this.name) ?(ILoadBalancer)this.propertiesFactory.get(ILoadBalancer.class, config, this.name) : new ZoneAwareLoadBalancer(config, rule, ping, serverList, serverListFilter,serverListUpdater));
}
标签:temp eager rand reload protect prope 自带 enabled bsp
原文地址:https://www.cnblogs.com/everyingo/p/14767874.html