SpringCloud gateway中有两种过滤器，路由过滤器（接口为GatewayFilter）和全局过滤器（接口为GlobalFilter）;
路由过滤器GatewayFilter的定义：
public interface GatewayFilter {
/**
* Process the Web request and (optionally) delegate to the next
* {@code WebFilter} through the given {@link GatewayFilterChain}.
* @param exchange the current server exchange
* @param chain provides a way to delegate to the next filter
* @return {@code Mono<Void>} to indicate when request processing is complete
*/
Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);
}
全局过滤器GlobalFilter的定义：
public interface GlobalFilter {
/**
* Process the Web request and (optionally) delegate to the next
* {@code WebFilter} through the given {@link GatewayFilterChain}.
* @param exchange the current server exchange
* @param chain provides a way to delegate to the next filter
* @return {@code Mono<Void>} to indicate when request processing is complete
*/
Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);
}
在FilteringWebHandler中会对所有的路由过滤器和全局过滤器进行调用，封装了一个DefaultGatewayFilterChain类，在这个类中统一对路由过滤器和全局过滤器进行调用，但是他们分属不同的接口，这里采用了适配器模式，适配接口GatewayFilterAdapter完成了将GlobalFilter接口适配成GatewayFilter；
private static class GatewayFilterAdapter implements GatewayFilter {
private final GlobalFilter delegate;
public GatewayFilterAdapter(GlobalFilter delegate) {
this.delegate = delegate;
}
@Override
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
return this.delegate.filter(exchange, chain);
}
}
这样在FilteringWebHandler中就可以将这两种过滤器存放到一个List中：
public class FilteringWebHandler implements WebHandler {
/**
* 全局过滤器
*/
private final List<GatewayFilter> globalFilters;
public FilteringWebHandler(List<GlobalFilter> globalFilters) {
this.globalFilters = loadFilters(globalFilters);
}
private static List<GatewayFilter> loadFilters(List<GlobalFilter> filters) {
return filters.stream()
.map(filter -> {
GatewayFilterAdapter gatewayFilter = new GatewayFilterAdapter(filter);
if (filter instanceof Ordered) {
int order = ((Ordered) filter).getOrder();
return new OrderedGatewayFilter(gatewayFilter, order);
}
return gatewayFilter;
}).collect(Collectors.toList());
}
}
在DefaultGatewayFilterChain.filter方法中就可以用同样的方式调用：
private static class DefaultGatewayFilterChain implements GatewayFilterChain {
private int index;
private final List<GatewayFilter> filters;
public DefaultGatewayFilterChain(List<GatewayFilter> filters) {
this.filters = filters;
}
@Override
public Mono<Void> filter(ServerWebExchange exchange) {
if (this.index < filters.size()) {
GatewayFilter filter = filters.get(this.index++);
return filter.filter(exchange, this);
} else {
return Mono.empty(); // complete
}
}
}
