本篇内容介绍了“spring cloud gateway集成hystrix的方法”的有关知识，在实际案例的操作过程中，不少人都会遇到这样的困境，接下来就让小编带领大家学习一下如何处理这些情况吧！希望大家仔细阅读，能够学有所成！
本文主要研究一下spring cloud gateway如何集成hystrix
<dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-hystrix</artifactId> </dependency>
添加spring-cloud-starter-netflix-hystrix依赖，开启hystrix
hystrix.command.fallbackcmd.execution.isolation.thread.timeoutInMilliseconds: 5000
spring:
cloud:
gateway:
discovery:
locator:
enabled: true
routes:
- id: employee-service
uri: lb://employee-service
predicates:
- Path=/employee/**
filters:
- RewritePath=/employee/(?<path>.*), /$\{path}
- name: Hystrix
args:
name: fallbackcmd
fallbackUri: forward:/fallback首先filter里头配置了name为Hystrix的filter，实际是对应HystrixGatewayFilterFactory
然后指定了hystrix command的名称，及fallbackUri，注意fallbackUri要以forward开头
最后通过hystrix.command.fallbackcmd.execution.isolation.thread.timeoutInMilliseconds指定该command的超时时间
@RestController
@RequestMapping("/fallback")
public class FallbackController {
@RequestMapping("")
public String fallback(){
return "error";
}
}GatewayAutoConfiguration
spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/config/GatewayAutoConfiguration.java
@Configuration
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@EnableConfigurationProperties
@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)
@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {
//......
@Configuration
@ConditionalOnClass({HystrixObservableCommand.class, RxReactiveStreams.class})
protected static class HystrixConfiguration {
@Bean
public HystrixGatewayFilterFactory hystrixGatewayFilterFactory(DispatcherHandler dispatcherHandler) {
return new HystrixGatewayFilterFactory(dispatcherHandler);
}
}
//......
}引入spring-cloud-starter-netflix-hystrix类库，就有HystrixObservableCommand.class, RxReactiveStreams.class，便开启HystrixConfiguration
HystrixGatewayFilterFactory
spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/HystrixGatewayFilterFactory.java
/**
* Depends on `spring-cloud-starter-netflix-hystrix`, {@see http://cloud.spring.io/spring-cloud-netflix/}
* @author Spencer Gibb
*/
public class HystrixGatewayFilterFactory extends AbstractGatewayFilterFactory<HystrixGatewayFilterFactory.Config> {
public static final String FALLBACK_URI = "fallbackUri";
private final DispatcherHandler dispatcherHandler;
public HystrixGatewayFilterFactory(DispatcherHandler dispatcherHandler) {
super(Config.class);
this.dispatcherHandler = dispatcherHandler;
}
@Override
public List<String> shortcutFieldOrder() {
return Arrays.asList(NAME_KEY);
}
public GatewayFilter apply(String routeId, Consumer<Config> consumer) {
Config config = newConfig();
consumer.accept(config);
if (StringUtils.isEmpty(config.getName()) && !StringUtils.isEmpty(routeId)) {
config.setName(routeId);
}
return apply(config);
}
@Override
public GatewayFilter apply(Config config) {
//TODO: if no name is supplied, generate one from command id (useful for default filter)
if (config.setter == null) {
Assert.notNull(config.name, "A name must be supplied for the Hystrix Command Key");
HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey(getClass().getSimpleName());
HystrixCommandKey commandKey = HystrixCommandKey.Factory.asKey(config.name);
config.setter = Setter.withGroupKey(groupKey)
.andCommandKey(commandKey);
}
return (exchange, chain) -> {
RouteHystrixCommand command = new RouteHystrixCommand(config.setter, config.fallbackUri, exchange, chain);
return Mono.create(s -> {
Subscription sub = command.toObservable().subscribe(s::success, s::error, s::success);
s.onCancel(sub::unsubscribe);
}).onErrorResume((Function<Throwable, Mono<Void>>) throwable -> {
if (throwable instanceof HystrixRuntimeException) {
HystrixRuntimeException e = (HystrixRuntimeException) throwable;
if (e.getFailureType() == TIMEOUT) { //TODO: optionally set status
setResponseStatus(exchange, HttpStatus.GATEWAY_TIMEOUT);
return exchange.getResponse().setComplete();
}
}
return Mono.error(throwable);
}).then();
};
}
//......
}这里创建了RouteHystrixCommand，将其转换为Mono，然后在onErrorResume的时候判断如果HystrixRuntimeException的failureType是FailureType.TIMEOUT类型的话，则返回GATEWAY_TIMEOUT(504, "Gateway Timeout")状态码。
RouteHystrixCommand
//TODO: replace with HystrixMonoCommand that we write
private class RouteHystrixCommand extends HystrixObservableCommand<Void> {
private final URI fallbackUri;
private final ServerWebExchange exchange;
private final GatewayFilterChain chain;
RouteHystrixCommand(Setter setter, URI fallbackUri, ServerWebExchange exchange, GatewayFilterChain chain) {
super(setter);
this.fallbackUri = fallbackUri;
this.exchange = exchange;
this.chain = chain;
}
@Override
protected Observable<Void> construct() {
return RxReactiveStreams.toObservable(this.chain.filter(exchange));
}
@Override
protected Observable<Void> resumeWithFallback() {
if (this.fallbackUri == null) {
return super.resumeWithFallback();
}
//TODO: copied from RouteToRequestUrlFilter
URI uri = exchange.getRequest().getURI();
//TODO: assume always?
boolean encoded = containsEncodedParts(uri);
URI requestUrl = UriComponentsBuilder.fromUri(uri)
.host(null)
.port(null)
.uri(this.fallbackUri)
.build(encoded)
.toUri();
exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, requestUrl);
ServerHttpRequest request = this.exchange.getRequest().mutate().uri(requestUrl).build();
ServerWebExchange mutated = exchange.mutate().request(request).build();
return RxReactiveStreams.toObservable(HystrixGatewayFilterFactory.this.dispatcherHandler.handle(mutated));
}
}这里重写了construct方法，RxReactiveStreams.toObservable(this.chain.filter(exchange))，将reactor的Mono转换为rxjava的Observable
这里重写了resumeWithFallback方法，针对有fallbackUri的情况，重新路由到fallbackUri的地址
public static class Config {
private String name;
private Setter setter;
private URI fallbackUri;
public String getName() {
return name;
}
public Config setName(String name) {
this.name = name;
return this;
}
public Config setFallbackUri(String fallbackUri) {
if (fallbackUri != null) {
setFallbackUri(URI.create(fallbackUri));
}
return this;
}
public URI getFallbackUri() {
return fallbackUri;
}
public void setFallbackUri(URI fallbackUri) {
if (fallbackUri != null && !"forward".equals(fallbackUri.getScheme())) {
throw new IllegalArgumentException("Hystrix Filter currently only supports 'forward' URIs, found " + fallbackUri);
}
this.fallbackUri = fallbackUri;
}
public Config setSetter(Setter setter) {
this.setter = setter;
return this;
}
}可以看到Config校验了fallbackUri，如果不为null，则必须以forward开头
spring cloud gateway集成hystrix，分为如下几步：
添加spring-cloud-starter-netflix-hystrix依赖
在对应route的filter添加name为Hystrix的filter，同时指定hystrix command的名称，及其fallbackUri(可选)
指定该hystrix command的超时时间等。
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