Java使用Gateway自定义负载均衡过滤器

<spring-cloud.version>Greenwich.SR2</spring-cloud.version>
<spring-boot.version>2.1.6.RELEASE</spring-boot.version>

#网关名
spring.cloud.gateway.routes[0].id=route-my-service-id
#网关uri，lb代表负载均衡，后面是服务名，必须要和微服务名一致，不能错，错了肯定不能路由
spring.cloud.gateway.routes[0].uri=lb://my-service-id
#断言，配置的路径
spring.cloud.gateway.routes[0].predicates[0]=Path=/my-service-id/v3/**
#截取uri前面两个位置的
spring.cloud.gateway.routes[0].filters[0]=StripPrefix=2

/**
 * @author Spencer Gibb
 */
@Configuration
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@EnableConfigurationProperties
@AutoConfigureBefore({ HttpHandlerAutoConfiguration.class,
		WebFluxAutoConfiguration.class })
@AutoConfigureAfter({ GatewayLoadBalancerClientAutoConfiguration.class,
		GatewayClassPathWarningAutoConfiguration.class })
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {

	@Bean
	public StringToZonedDateTimeConverter stringToZonedDateTimeConverter() {
		return new StringToZonedDateTimeConverter();
	}

	@Bean
	public RouteLocatorBuilder routeLocatorBuilder(
			ConfigurableApplicationContext context) {
		return new RouteLocatorBuilder(context);
	}

	@Bean
	@ConditionalOnMissingBean
	public PropertiesRouteDefinitionLocator propertiesRouteDefinitionLocator(
			GatewayProperties properties) {
		return new PropertiesRouteDefinitionLocator(properties);
	}
省略.......

/**
 * @author Spencer Gibb
 */
@Configuration
@ConditionalOnClass({ LoadBalancerClient.class, RibbonAutoConfiguration.class,
		DispatcherHandler.class })
@AutoConfigureAfter(RibbonAutoConfiguration.class)
@EnableConfigurationProperties(LoadBalancerProperties.class)
public class GatewayLoadBalancerClientAutoConfiguration {

	// GlobalFilter beans

	//负载均衡
	@Bean
	@ConditionalOnBean(LoadBalancerClient.class)
	@ConditionalOnMissingBean(LoadBalancerClientFilter.class)
	public LoadBalancerClientFilter loadBalancerClientFilter(LoadBalancerClient client,
			LoadBalancerProperties properties) {
		return new LoadBalancerClientFilter(client, properties);
	}

}

protected ServiceInstance choose(ServerWebExchange exchange) {
		return loadBalancer.choose(
				((URI) exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR)).getHost());
	}

/**
 * @Description 自定义负载均衡
 * @Author Singh
 * @Date 2020-07-02 10:36
 * @Version
 **/
public class CustomLoadBalancerClientFilter extends LoadBalancerClientFilter implements BeanPostProcessor {

  private final DiscoveryClient discoveryClient;

  private final List<IChooseRule> chooseRules;

  public CustomLoadBalancerClientFilter(LoadBalancerClient loadBalancer,
                     LoadBalancerProperties properties,
                     DiscoveryClient discoveryClient) {
    super(loadBalancer, properties);
    this.discoveryClient = discoveryClient;
    this.chooseRules = new ArrayList<>();
    chooseRules.add(new EngineeringChooseRule());
  }

  protected ServiceInstance choose(ServerWebExchange exchange) {
    if(!CollectionUtils.isEmpty(chooseRules)){
      Iterator<IChooseRule> iChooseRuleIterator = chooseRules.iterator();
      while (iChooseRuleIterator.hasNext()){
        IChooseRule chooseRule = iChooseRuleIterator.next();
        ServiceInstance choose = chooseRule.choose(exchange,discoveryClient);
        if(choose != null){
          return choose;
        }
      }
    }
    return loadBalancer.choose(
        ((URI) exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR)).getHost());
  }
}

/**
 * @Description 自定义选择实例规则
 * @Author Singh
 * @Date 2020-07-02 11:03
 * @Version
 **/
public interface IChooseRule {

  /**
   * 返回null那么使用gateway默认的负载均衡策略
   * @param exchange
   * @param discoveryClient
   * @return
   */
  ServiceInstance choose(ServerWebExchange exchange, DiscoveryClient discoveryClient);

}

/**
 * @Description 微服务负载均衡策略
 * @Author Singh
 * @Date 2020-07-02 11:10
 * @Version
 **/
public class EngineeringChooseRule implements IChooseRule {

  @Override
  public ServiceInstance choose(ServerWebExchange exchange, DiscoveryClient discoveryClient) {
    URI originalUrl = (URI) exchange.getAttributes().get(GATEWAY_REQUEST_URL_ATTR);
    String instancesId = originalUrl.getHost();
    if(instancesId.equals("my-service-id")){
      if(originalUrl.getPath().contains("/files/upload")){
        try{
          List<ServiceInstance> instances = discoveryClient.getInstances(instancesId);
          MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
          String uuid = queryParams.get("uuid").get(0);
          int hash = uuid.hashCode() >>> 16 ;
          int index = hash % instances.size();
          return instances.get(index);
        }catch (Exception e){
          //do nothing
        }
      }
    }

    return null;
  }
}

/**
 * @Description
 * @Author Singh
 * @Date 2020-07-01 17:57
 * @Version
 **/
@Configuration
public class GetawayConfig {

//  @Bean
//  public RouteLocator routeLocator(RouteLocatorBuilder builder) {
//    //lb://hjhn-engineering/files/upload
//    return builder.routes()
//        .route(r ->r.path("/**").filters(
//                    f -> f.stripPrefix(2).filters(new EngineeringGatewayFilter())
//                ).uri("lb://hjhn-engineering")
//        ) .build();
//  }

  @Bean
  public LoadBalancerClientFilter loadBalancerClientFilter(LoadBalancerClient client,
                               LoadBalancerProperties properties,
                              DiscoveryClient discoveryClient) {
      return new CustomLoadBalancerClientFilter(client, properties,discoveryClient);
  }

}