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Java在SpringCloud中自定义Gateway负载均衡策略

一、前言

spring-cloud-starter-netflix-ribbon已经不再更新了，最新版本是2.2.10.RELEASE，最后更新时间是2021年11月18日，详细信息可以看maven官方仓库：org.springframework.cloud/spring-cloud-starter-netflix-ribbon，SpringCloud官方推荐使用spring-cloud-starter-loadbalancer进行负载均衡。

背景：大文件上传做切片文件上传；

流程：将切片文件上传到服务器，然后进行合并任务，合并完成之后上传到对象存储；现在服务搞成多节点以后，网关默认走轮循，但是相同的服务在不同的机器上，这样就会导致切片文件散落在不同的服务器上，会导致文件合并失败；所以根据一个标识去自定义gateway对应服务的负载均衡策略，可以解决这个问题；

我的版本如下：

<spring-boot.version>2.7.3</spring-boot.version>
        <spring-cloud.version>2021.0.4</spring-cloud.version>
        <spring-cloud-alibaba.version>2021.0.4.0</spring-cloud-alibaba.version>

二、参考默认实现

springCloud原生默认的负载均衡策略是这个类：

org.springframework.cloud.loadbalancer.core.RoundRobinLoadBalancer

我们参考这个类实现自己的负载均衡策略即可，RoundRobinLoadBalancer实现了ReactorServiceInstanceLoadBalancer这个接口，实现了choose这个方法，如下图：

在choose方法中调用了processInstanceResponse方法，processInstanceResponse方法中调用了getInstanceResponse方法，所以我们我们可以复制RoundRobinLoadBalancer整个类，只修改getInstanceResponse这个方法里的内容就可以实现自定义负载均衡策略。

三、实现代码

原理：根据请求头当中设备的唯一标识传递到下游，唯一标识做哈希取余，可以指定对应的服务器节点，需要的服务设置自定义负载策略，不需要的服务设置默认的轮循机制即可.我这里是根据单独的接口请求地址去自定义,也可以根据服务名称自定义

package com.wondertek.gateway.loadBalancer;import cn.hutool.core.util.ObjectUtil;
import com.wondertek.web.exception.enums.HttpRequestHeaderEnum;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;
@Slf4j
@Component
public class RequestFilter implements GlobalFilter, Ordered {@Overridepublic int getOrder() {// 应该小于LoadBalancerClientFilter的顺序值return Ordered.HIGHEST_PRECEDENCE;}@Overridepublic Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {ServerHttpRequest request = exchange.getRequest();String clientDeviceUniqueCode = request.getHeaders().getFirst(HttpRequestHeaderEnum.CLIENT_DEVICE_UNIQUE_CODE.getCode());// 存入Reactor上下文String resultCode = clientDeviceUniqueCode;//路径String pathUrl = request.getURI().getPath();/*** ^ 锚点匹配输入字符串的开始位置。*  /(oms-api|unity-api|cloud-api) 匹配以 /oms-api 或 /unity-api 或 /cloud-api 开始的任何字符串。*  replaceFirst() 方法用空字符串替换第一次匹配的内容，也就是我们想要去掉的服务名称。*/String resultPathUrl = pathUrl.replaceFirst("^/(oms-api|unity-api|cloud-api)", "");return chain.filter(exchange).contextWrite(context -> {if (ObjectUtil.isNotEmpty(resultCode) && ObjectUtil.isNotEmpty(resultPathUrl)) {log.info("开始将request中的唯一标识封装到上下游中:{},请求path是:{}", resultCode, resultPathUrl);return context.put("identification", resultCode).put("pathUrl", resultPathUrl);} else {//根据需求进行其他处理return context;}});}
}

package com.wondertek.gateway.loadBalancer;import cn.hutool.core.util.ObjectUtil;
import com.wondertek.center.constants.BusinessCenterApi;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.DefaultResponse;
import org.springframework.cloud.client.loadbalancer.EmptyResponse;
import org.springframework.cloud.client.loadbalancer.Request;
import org.springframework.cloud.client.loadbalancer.Response;
import org.springframework.cloud.loadbalancer.core.NoopServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer;
import org.springframework.cloud.loadbalancer.core.SelectedInstanceCallback;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import reactor.core.publisher.Mono;import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;@Slf4j
public class ClientDeviceUniqueCodeInstanceLoadBalancer implements ReactorServiceInstanceLoadBalancer {private final String serviceId;final AtomicInteger position;private ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;public ClientDeviceUniqueCodeInstanceLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId, AtomicInteger position) {this.serviceId = serviceId;this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;this.position = position;}@Overridepublic Mono<Response<ServiceInstance>> choose(Request request) {//在 choose 方法中，使用 deferContextual 方法来访问上下文并提取客户端标识。这里的 getOrDefault 方法尝试从上下文中获取一个键为 "identification" 的值，如果不存在则返回 "default-identification"return Mono.deferContextual(contextView -> {String identification = contextView.getOrDefault("identification", "");log.info("上下游获取到的identification的值为:{}", identification);String pathUrl = contextView.getOrDefault("pathUrl", "");log.info("上下游获取到的pathUrl的值为:{}", pathUrl);ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);return supplier.get(request).next().map(serviceInstances -> processInstanceResponse(supplier, serviceInstances, identification, pathUrl));});}private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier, List<ServiceInstance> serviceInstances, String identification, String pathUrl) {Response<ServiceInstance> serviceInstanceResponse;//特定接口走自定义负载策略Boolean status = ObjectUtil.isNotEmpty(identification) && ObjectUtil.isNotEmpty(pathUrl) &&(pathUrl.contains(BusinessCenterApi.WEB_UPLOAD_SLICE_FILE) ||pathUrl.contains(BusinessCenterApi.WEB_MERGE_SLICE_FILE) ||pathUrl.contains(BusinessCenterApi.UNITY_UPLOAD_SLICE_FILE) ||pathUrl.contains(BusinessCenterApi.UNITY_MERGE_SLICE_FILE) ||pathUrl.contains(BusinessCenterApi.CLOUD_UPLOAD_SLICE_FILE) ||pathUrl.contains(BusinessCenterApi.CLOUD_MERGE_SLICE_FILE));if (status) {serviceInstanceResponse = this.getIpInstanceResponse(serviceInstances, identification);} else {serviceInstanceResponse = this.getInstanceResponse(serviceInstances);}if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {((SelectedInstanceCallback) supplier).selectedServiceInstance((ServiceInstance) serviceInstanceResponse.getServer());}return serviceInstanceResponse;}private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {if (instances.isEmpty()) {if (log.isWarnEnabled()) {log.warn("No servers available for service: " + this.serviceId);}return new EmptyResponse();} else {//创建一个新的列表以避免在原始列表上排序,避免了修改共享状态可能带来的线程安全问题List<ServiceInstance> sortedInstances = new ArrayList<>(instances);// 现在对新列表进行排序，保持原始列表的顺序不变Collections.sort(sortedInstances, Comparator.comparing(ServiceInstance::getHost));//log.info("获取到的实例个数的值为:{}", sortedInstances.size());sortedInstances.forEach(instance -> log.info("排序后的实例: {},{}", instance.getHost(), instance.getPort()));int pos = Math.abs(this.position.incrementAndGet());//log.info("默认轮循机制,pos递加后的值为:{}", pos);int positionIndex = pos % instances.size();//log.info("取余后的positionIndex的值为:{}", positionIndex);ServiceInstance instance = instances.get(positionIndex);//log.info("instance.getUri()的值为:{}", instance.getUri());log.info("特殊服务,默认轮循机制,routed to instance: {}:{}", instance.getHost(), instance.getPort());return new DefaultResponse(instance);}}private Response<ServiceInstance> getIpInstanceResponse(List<ServiceInstance> instances, String identification) {if (instances.isEmpty()) {log.warn("No servers available for service: " + this.serviceId);return new EmptyResponse();} else {//创建一个新的列表以避免在原始列表上排序,避免了修改共享状态可能带来的线程安全问题List<ServiceInstance> sortedInstances = new ArrayList<>(instances);// 现在对新列表进行排序，保持原始列表的顺序不变Collections.sort(sortedInstances, Comparator.comparing(ServiceInstance::getHost));//log.info("获取到的实例个数的值为:{}", sortedInstances.size());sortedInstances.forEach(instance -> log.info("排序后的实例: {},{}", instance.getHost(), instance.getPort()));//log.info("多个服务实例，使用客户端 identification 地址的哈希值来选择服务实例");// 使用排序后的列表来找到实例int ipHashCode = Math.abs(identification.hashCode());//log.info("identificationHashCode的值为:{}", ipHashCode);int instanceIndex = ipHashCode % sortedInstances.size();//log.info("instanceIndex的值为:{}", instanceIndex);ServiceInstance instanceToReturn = sortedInstances.get(instanceIndex);//log.info("instanceToReturn.getUri()的值为:{}", instanceToReturn.getUri());log.info("特殊服务,自定义identification负载机制,Client identification: {} is routed to instance: {}:{}", identification, instanceToReturn.getHost(), instanceToReturn.getPort());return new DefaultResponse(instanceToReturn);}}}

package com.wondertek.gateway.loadBalancer;import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.cloud.client.ServiceInstance;
import org.springframework.cloud.client.loadbalancer.DefaultResponse;
import org.springframework.cloud.client.loadbalancer.EmptyResponse;
import org.springframework.cloud.client.loadbalancer.Request;
import org.springframework.cloud.client.loadbalancer.Response;
import org.springframework.cloud.loadbalancer.core.NoopServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer;
import org.springframework.cloud.loadbalancer.core.SelectedInstanceCallback;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import reactor.core.publisher.Mono;import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;@Slf4j
public class DefaultInstanceLoadBalancer implements ReactorServiceInstanceLoadBalancer {private final String serviceId;private ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;final AtomicInteger position;public DefaultInstanceLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId, AtomicInteger position) {this.serviceId = serviceId;this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;this.position = position;}@Overridepublic Mono<Response<ServiceInstance>> choose(Request request) {ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);return supplier.get(request).next().map(serviceInstances -> processInstanceResponse(supplier, serviceInstances));}private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier,List<ServiceInstance> serviceInstances) {Response<ServiceInstance> serviceInstanceResponse = getInstanceResponse(serviceInstances);if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {((SelectedInstanceCallback) supplier).selectedServiceInstance(serviceInstanceResponse.getServer());}return serviceInstanceResponse;}private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {if (instances.isEmpty()) {if (log.isWarnEnabled()) {log.warn("No servers available for service: " + serviceId);}return new EmptyResponse();}//创建一个新的列表以避免在原始列表上排序,避免了修改共享状态可能带来的线程安全问题List<ServiceInstance> sortedInstances = new ArrayList<>(instances);// 现在对新列表进行排序，保持原始列表的顺序不变Collections.sort(sortedInstances, Comparator.comparing(ServiceInstance::getHost));//log.info("获取到的实例个数的值为:{}", sortedInstances.size());sortedInstances.forEach(instance -> log.info("排序后的实例: {},{}", instance.getHost(), instance.getPort()));int pos = Math.abs(this.position.incrementAndGet());//log.info("默认轮循机制,pos递加后的值为:{}", pos);int positionIndex = pos % instances.size();//log.info("取余后的positionIndex的值为:{}", positionIndex);ServiceInstance instance = instances.get(positionIndex);//log.info("instance.getUri()的值为:{}", instance.getUri());log.info("默认轮循机制,routed to instance: {}:{}",instance.getHost(), instance.getPort());return new DefaultResponse(instance);}}

package com.wondertek.gateway.loadBalancer;import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClient;
import org.springframework.cloud.loadbalancer.annotation.LoadBalancerClients;
import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer;
import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier;
import org.springframework.cloud.loadbalancer.support.LoadBalancerClientFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;import java.util.concurrent.atomic.AtomicInteger;@Configuration
//单台服务
//@LoadBalancerClient(name = "oms-api", configuration = CustomLoadBalancerConfig.class)
//多台服务
@LoadBalancerClients({@LoadBalancerClient(name = "oms-api", configuration = CustomLoadBalancerConfig.class),@LoadBalancerClient(name = "unity-api", configuration = CustomLoadBalancerConfig.class),@LoadBalancerClient(name = "cloud-api", configuration = CustomLoadBalancerConfig.class),@LoadBalancerClient(name = "open-api", configuration = CustomLoadBalancerConfig.class),@LoadBalancerClient(name = "server-api", configuration = CustomLoadBalancerConfig.class),@LoadBalancerClient(name = "center-service", configuration = CustomLoadBalancerConfig.class),
})
@Slf4j
public class CustomLoadBalancerConfig {// 定义一个Bean来提供AtomicInteger的实例@Beanpublic AtomicInteger positionTracker() {// 这将在应用上下文中只初始化一次return new AtomicInteger(0);}//自定义优先级负载均衡器@Beanpublic ReactorServiceInstanceLoadBalancer customPriorityLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider,Environment environment,AtomicInteger positionTracker) {String serviceId = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);//目的为解决文件上传切片文件分散上传的问题if ("oms-api".equals(serviceId)||"unity-api".equals(serviceId)||"cloud-api".equals(serviceId)){//log.info("服务名称:serviceId:{},走自定义clientDeviceUniqueCode负载模式", serviceId);return new ClientDeviceUniqueCodeInstanceLoadBalancer(serviceInstanceListSupplierProvider, serviceId, positionTracker);}//log.info("服务名称:serviceId:{},走默认负载模式", serviceId);return new DefaultInstanceLoadBalancer(serviceInstanceListSupplierProvider, serviceId,positionTracker);}
}

【SpringCloud系列】开发环境下重写Loadbalancer实现自定义负载均衡