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本文主要研究一下spring cloud的DiscoveryClientRouteDefinitionLocator
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 {
//......
@Bean
@ConditionalOnMissingBean
public PropertiesRouteDefinitionLocator propertiesRouteDefinitionLocator(GatewayProperties properties) {
return new PropertiesRouteDefinitionLocator(properties);
}
@Bean
@ConditionalOnMissingBean(RouteDefinitionRepository.class)
public InMemoryRouteDefinitionRepository inMemoryRouteDefinitionRepository() {
return new InMemoryRouteDefinitionRepository();
}
@Bean
@Primary
public RouteDefinitionLocator routeDefinitionLocator(List<RouteDefinitionLocator> routeDefinitionLocators) {
return new CompositeRouteDefinitionLocator(Flux.fromIterable(routeDefinitionLocators));
}
//......
}
这里注册了CompositeRouteDefinitionLocator
GatewayDiscoveryClientAutoConfiguration
spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/discovery/GatewayDiscoveryClientAutoConfiguration.java
@Configuration
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@AutoConfigureBefore(GatewayAutoConfiguration.class)
@ConditionalOnClass({DispatcherHandler.class, DiscoveryClient.class})
@EnableConfigurationProperties
public class GatewayDiscoveryClientAutoConfiguration {
@Bean
@ConditionalOnBean(DiscoveryClient.class)
@ConditionalOnProperty(name = "spring.cloud.gateway.discovery.locator.enabled")
public DiscoveryClientRouteDefinitionLocator discoveryClientRouteDefinitionLocator(
DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
}
@Bean
public DiscoveryLocatorProperties discoveryLocatorProperties() {
DiscoveryLocatorProperties properties = new DiscoveryLocatorProperties();
properties.setPredicates(initPredicates());
properties.setFilters(initFilters());
return properties;
}
public static List<PredicateDefinition> initPredicates() {
ArrayList<PredicateDefinition> definitions = new ArrayList<>();
// TODO: add a predicate that matches the url at /serviceId?
// add a predicate that matches the url at /serviceId/**
PredicateDefinition predicate = new PredicateDefinition();
predicate.setName(normalizeRoutePredicateName(PathRoutePredicateFactory.class));
predicate.addArg(PATTERN_KEY, "'/'+serviceId+'/**'");
definitions.add(predicate);
return definitions;
}
public static List<FilterDefinition> initFilters() {
ArrayList<FilterDefinition> definitions = new ArrayList<>();
// add a filter that removes /serviceId by default
FilterDefinition filter = new FilterDefinition();
filter.setName(normalizeFilterFactoryName(RewritePathGatewayFilterFactory.class));
String regex = "'/' + serviceId + '/(?<remaining>.*)'";
String replacement = "'/${remaining}'";
filter.addArg(REGEXP_KEY, regex);
filter.addArg(REPLACEMENT_KEY, replacement);
definitions.add(filter);
return definitions;
}
}
默认配置了一个根据serviceId进行rewrite的filter
DiscoveryLocatorProperties
spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/discovery/DiscoveryLocatorProperties.java
@ConfigurationProperties("spring.cloud.gateway.discovery.locator")
public class DiscoveryLocatorProperties {
/** Flag that enables DiscoveryClient gateway integration */
private boolean enabled = false;
/**
* The prefix for the routeId, defaults to discoveryClient.getClass().getSimpleName() + "_".
* Service Id will be appended to create the routeId.
*/
private String routeIdPrefix;
/**
* SpEL expression that will evaluate whether to include a service in gateway integration or not,
* defaults to: true
*/
private String includeExpression = "true";
/** SpEL expression that create the uri for each route, defaults to: 'lb://'+serviceId */
private String urlExpression = "'lb://'+serviceId";
/**
* Option to lower case serviceId in predicates and filters, defaults to false.
* Useful with eureka when it automatically uppercases serviceId.
* so MYSERIVCE, would match /myservice/**
*/
private boolean lowerCaseServiceId = false;
private List<PredicateDefinition> predicates = new ArrayList<>();
private List<FilterDefinition> filters = new ArrayList<>();
//......
@Override
public String toString() {
return new ToStringCreator(this)
.append("enabled", enabled)
.append("routeIdPrefix", routeIdPrefix)
.append("includeExpression", includeExpression)
.append("urlExpression", urlExpression)
.append("lowerCaseServiceId", lowerCaseServiceId)
.append("predicates", predicates)
.append("filters", filters)
.toString();
}
}
- 默认lowerCaseServiceId为false,因为eureka默认把serviceId大写
- urlExpression默认为'lb://'+serviceId
DiscoveryClientRouteDefinitionLocator
spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/discovery/DiscoveryClientRouteDefinitionLocator.java
public class DiscoveryClientRouteDefinitionLocator implements RouteDefinitionLocator {
private final DiscoveryClient discoveryClient;
private final DiscoveryLocatorProperties properties;
private final String routeIdPrefix;
public DiscoveryClientRouteDefinitionLocator(DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
this.discoveryClient = discoveryClient;
this.properties = properties;
if (StringUtils.hasText(properties.getRouteIdPrefix())) {
this.routeIdPrefix = properties.getRouteIdPrefix();
} else {
this.routeIdPrefix = this.discoveryClient.getClass().getSimpleName() + "_";
}
}
@Override
public Flux<RouteDefinition> getRouteDefinitions() {
SimpleEvaluationContext evalCtxt = SimpleEvaluationContext
.forReadOnlyDataBinding()
.withInstanceMethods()
.build();
SpelExpressionParser parser = new SpelExpressionParser();
Expression includeExpr = parser.parseExpression(properties.getIncludeExpression());
Expression urlExpr = parser.parseExpression(properties.getUrlExpression());
return Flux.fromIterable(discoveryClient.getServices())
.map(discoveryClient::getInstances)
.filter(instances -> !instances.isEmpty())
.map(instances -> instances.get(0))
.filter(instance -> {
Boolean include = includeExpr.getValue(evalCtxt, instance, Boolean.class);
if (include == null) {
return false;
}
return include;
})
.map(instance -> {
String serviceId = instance.getServiceId();
RouteDefinition routeDefinition = new RouteDefinition();
routeDefinition.setId(this.routeIdPrefix + serviceId);
String uri = urlExpr.getValue(evalCtxt, instance, String.class);
routeDefinition.setUri(URI.create(uri));
final ServiceInstance instanceForEval = new DelegatingServiceInstance(instance, properties);
for (PredicateDefinition original : this.properties.getPredicates()) {
PredicateDefinition predicate = new PredicateDefinition();
predicate.setName(original.getName());
for (Map.Entry<String, String> entry : original.getArgs().entrySet()) {
String value = getValueFromExpr(evalCtxt, parser, instanceForEval, entry);
predicate.addArg(entry.getKey(), value);
}
routeDefinition.getPredicates().add(predicate);
}
for (FilterDefinition original : this.properties.getFilters()) {
FilterDefinition filter = new FilterDefinition();
filter.setName(original.getName());
for (Map.Entry<String, String> entry : original.getArgs().entrySet()) {
String value = getValueFromExpr(evalCtxt, parser, instanceForEval, entry);
filter.addArg(entry.getKey(), value);
}
routeDefinition.getFilters().add(filter);
}
return routeDefinition;
});
}
String getValueFromExpr(SimpleEvaluationContext evalCtxt, SpelExpressionParser parser, ServiceInstance instance, Map.Entry<String, String> entry) {
Expression valueExpr = parser.parseExpression(entry.getValue());
return valueExpr.getValue(evalCtxt, instance, String.class);
}
//......
}
可以看到这里从discoveryClient.getServices()获取注册信息转换为RouteDefinition
小结
RouteDefinitionLocator接口有不同的实现类:
- InMemoryRouteDefinitionRepository
- CompositeRouteDefinitionLocator
- DiscoveryClientRouteDefinitionLocator
- PropertiesRouteDefinitionLocator
- CachingRouteDefinitionLocator
如果开启spring.cloud.gateway.discovery.locator.enabled=true,那么最后CompositeRouteDefinitionLocator则是组合了InMemoryRouteDefinitionRepository、PropertiesRouteDefinitionLocator、DiscoveryClientRouteDefinitionLocator三个RouteDefinitionLocator
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