【源码】Spring Cloud Gateway 启动时加载并缓存路由

import org.springframework.cloud.gateway.route.RouteDefinition;
import org.springframework.cloud.gateway.route.RouteDefinitionWriter;
import org.springframework.context.ApplicationEventPublisher;
import reactor.core.publisher.Mono;
 
import java.util.HashMap;
import java.util.Map;
 
public class CachingRouteDefinitionWriter implements RouteDefinitionWriter {
 
    private final RouteDefinitionWriter delegate;
    private final ApplicationEventPublisher publisher;
    private final Map<String, RouteDefinition> cache = new HashMap<>();
 
    public CachingRouteDefinitionWriter(RouteDefinitionWriter delegate, ApplicationEventPublisher publisher) {
        this.delegate = delegate;
        this.publisher = publisher;
    }
 
    @Override
    public Mono<Void> save(Mono<RouteDefinition> route) {
        return route.flatMap(r -> {
            cache.put(r.getId(), r);
            return delegate.save(Mono.just(r));
        });
    }
 
    @Override
    public Mono<Void> delete(Mono<String> routeId) {
        return routeId.flatMap(id -> {
            cache.remove(id);
            return delegate.delete(Mono.just(id));
        });
    }
 
    public Mono<RouteDefinition> get(String id) {
        return Mono.justOrEmpty(cache.get(id));
    }
}

这段代码实现了一个自定义的RouteDefinitionWriter，它在保存和删除路由定义时同步更新内存中的缓存。这样，Spring Cloud Gateway在启动时可以直接从缓存中加载路由配置，而无需每次都访问外部的路由源（如配置服务器），从而提高了路由配置加载的性能并简化了部署过程。