Spring-Cloud项目使用EnableAutoConfiguration注解自动
初始化配置信息，Spring-Cloud-Gateway同样，Spring-Cloud-Gateway下的spring.factories（在包spring-cloud-gateway-core）如下:
# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
//依赖包的校验配置
org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration,\
//网关的核心配置
org.springframework.cloud.gateway.config.GatewayAutoConfiguration,\
//负载均衡相关依赖配置信息
org.springframework.cloud.gateway.config.GatewayLoadBalancerClientAutoConfiguration,\
//流控的依赖配置信息
org.springframework.cloud.gateway.config.GatewayRedisAutoConfiguration,\
//注册中心相关的依赖配置
org.springframework.cloud.gateway.discovery.GatewayDiscoveryClientAutoConfiguration
配置功能
分析配置功能前先了解下springboot常用的注解的含义
执行顺序
@AutoConfigureAfter：在指定的配置类初始化后再加载
@AutoConfigureBefore：在指定的配置类初始化前加载
@AutoConfigureOrder：数越小越先初始化
条件配置
@ConditionalOnClass ： classpath中存在该类时起效
@ConditionalOnMissingClass ： classpath中不存在该类时起效
@ConditionalOnBean ： DI容器中存在该类型Bean时起效
@ConditionalOnMissingBean ： DI容器中不存在该类型Bean时起效
@ConditionalOnSingleCandidate ： DI容器中该类型Bean只有一个或@Primary的只有一个时起效
@ConditionalOnExpression ： SpEL表达式结果为true时
@ConditionalOnProperty ： 参数设置或者值一致时起效
@ConditionalOnResource ： 指定的文件存在时起效
@ConditionalOnJndi ： 指定的JNDI存在时起效
@ConditionalOnJava ： 指定的Java版本存在时起效
@ConditionalOnWebApplication ： Web应用环境下起效
@ConditionalOnNotWebApplication ： 非Web应用环境下起效
- GatewayClassPathWarningAutoConfiguration配置
GatewayClassPathWarningAutoConfiguration配置用于检查项目是否正确导入 spring-boot-starter-webflux 依赖，而不是错误导入 spring-boot-starter-web 依赖，同时 GatewayClassPathWarningAutoConfiguration配置在EnableAutoConfiguration配置加载前加载
接下来我看代码如何实现
@Configuration
//执行顺序注解
//当前注解标识需要在GatewayAutoConfiguration前加载此配置
@AutoConfigureBefore(GatewayAutoConfiguration.class)
public class GatewayClassPathWarningAutoConfiguration {
@Configuration
//条件判断注解
//classpath中存在org.springframework.web.servlet.DispatcherServlet时起效，标识项目导入了spring-boot-starter-web包
@ConditionalOnClass(name = "org.springframework.web.servlet.DispatcherServlet")
protected static class SpringMvcFoundOnClasspathConfiguration {
public SpringMvcFoundOnClasspathConfiguration() {
//当前项目导入了spring-boot-starter-web依赖时，打印警告日志
log.warn(BORDER+"Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. "+
"Please remove spring-boot-starter-web dependency."+BORDER);
}
}
@Configuration
//条件判断注解
//classpath中不存在org.springframework.web.reactive.DispatcherHandler时起效，标识项目未导入了spring-boot-starter-webflux包
@ConditionalOnMissingClass("org.springframework.web.reactive.DispatcherHandler")
protected static class WebfluxMissingFromClasspathConfiguration {
public WebfluxMissingFromClasspathConfiguration() {
//当前项目未导入了boot-starter-webflux依赖时，打印警告日志
log.warn(BORDER+"Spring Webflux is missing from the classpath, which is required for Spring Cloud Gateway at this time. "+
"Please add spring-boot-starter-webflux dependency."+BORDER);
}
}
}
- GatewayLoadBalancerClientAutoConfiguration
GatewayLoadBalancerClientAutoConfiguration配置作用是初始化 LoadBalancerClientFilter 路由的负载均衡拦截器
@Configuration
//条件判断注解
//classpath中存在LoadBalancerClient和RibbonAutoConfiguration和DispatcherHandler时此配置起效
@ConditionalOnClass({LoadBalancerClient.class, RibbonAutoConfiguration.class, DispatcherHandler.class})
//执行顺序注解
@AutoConfigureAfter(RibbonAutoConfiguration.class)
public class GatewayLoadBalancerClientAutoConfiguration {
// GlobalFilter beans
@Bean
//条件判断注解
//DI容器中存在LoadBalancerClient类型Bean时起效
@ConditionalOnBean(LoadBalancerClient.class)
public LoadBalancerClientFilter loadBalancerClientFilter(LoadBalancerClient client) {
return new LoadBalancerClientFilter(client);
}
}
- GatewayRedisAutoConfiguration
GatewayRedisAutoConfiguration 配置作用是初始化初始化 RedisRateLimiter 限流功能的RequestRateLimiterGatewayFilterFactory 基于 RedisRateLimiter 实现网关的限流功能，代码略
- GatewayAutoConfiguration
GatewayAutoConfiguration配置是Spring Cloud Gateway 核心配置类，初始化如下 ：
- NettyConfiguration 底层通信netty配置
- GlobalFilter （AdaptCachedBodyGlobalFilter，RouteToRequestUrlFilter，ForwardRoutingFilter，ForwardPathFilter，WebsocketRoutingFilter，WeightCalculatorWebFilter等）
- FilteringWebHandler
- GatewayProperties
- PrefixPathGatewayFilterFactory
- RoutePredicateFactory
- RouteDefinitionLocator
- RouteLocator
- RoutePredicateHandlerMapping 查找匹配到 Route并进行处理
- GatewayWebfluxEndpoint 管理网关的 HTTP API
@Configuration
//条件注解
//通过 spring.cloud.gateway.enabled配置网关的开启与关闭
//matchIfMissing = true => 网关默认开启。
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@EnableConfigurationProperties
@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)
@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {
@Configuration
//当classpath中存在HttpClient起效
@ConditionalOnClass(HttpClient.class)
protected static class NettyConfiguration {
.....略
}
//加载配置beans
// ConfigurationProperty beans
@Bean
public GatewayProperties gatewayProperties() {
return new GatewayProperties();
}
@Bean
public SecureHeadersProperties secureHeadersProperties() {
return new SecureHeadersProperties();
}
// GlobalFilter beans
//加载全局的拦截器
@Bean
public AdaptCachedBodyGlobalFilter adaptCachedBodyGlobalFilter() {
return new AdaptCachedBodyGlobalFilter();
}
@Bean
public RouteToRequestUrlFilter routeToRequestUrlFilter() {
return new RouteToRequestUrlFilter();
}
@Bean
@ConditionalOnBean(DispatcherHandler.class)
public ForwardRoutingFilter forwardRoutingFilter(DispatcherHandler dispatcherHandler) {
return new ForwardRoutingFilter(dispatcherHandler);
}
@Bean
public ForwardPathFilter forwardPathFilter() {
return new ForwardPathFilter();
}
@Bean
public WebSocketService webSocketService() {
return new HandshakeWebSocketService();
}
@Bean
public WebsocketRoutingFilter websocketRoutingFilter(WebSocketClient webSocketClient,
return new WebsocketRoutingFilter(webSocketClient, webSocketService, headersFilters);
}
@Bean
public WeightCalculatorWebFilter weightCalculatorWebFilter(Validator validator) {
return new WeightCalculatorWebFilter(validator);
}
}
- GatewayDiscoveryClientAutoConfiguration
GatewayDiscoveryClientAutoConfiguration配置的作用是初始化配置路由中的注册发现服务信息
@Configuration
//同4
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@AutoConfigureBefore(GatewayAutoConfiguration.class)
@ConditionalOnClass({DispatcherHandler.class, DiscoveryClient.class})
@EnableConfigurationProperties
public class GatewayDiscoveryClientAutoConfiguration {
@Bean
//当classpath中存在DiscoveryClient起效
@ConditionalOnBean(DiscoveryClient.class)
//通过spring.cloud.gateway.discovery.locator.enabled配置注册中心查找的开启与关闭
@ConditionalOnProperty(name = "spring.cloud.gateway.discovery.locator.enabled")
public DiscoveryClientRouteDefinitionLocator discoveryClientRouteDefinitionLocator(
DiscoveryClient discoveryClient, DiscoveryLocatorProperties properties) {
return new DiscoveryClientRouteDefinitionLocator(discoveryClient, properties);
}
}
通过自动加载初始化上述五个配置实例Spring-Cloud-Gateway就完成自身的信息加载和初始化工作
