开发人员指南

这些是编写网关一些自定义组件的基本指南。

编写自定义路由断言工厂

为了编写路由断言，你需要将 RoutePredicateFactory 实现为一个 bean。你可以扩展一个名为 AbstractRoutePredicateFactory 的抽象类。

MyRoutePredicateFactory.java

@Component
public class MyRoutePredicateFactory extends AbstractRoutePredicateFactory<MyRoutePredicateFactory.Config> {

    public MyRoutePredicateFactory() {
        super(Config.class);
    }

    @Override
    public Predicate<ServerWebExchange> apply(Config config) {
        // grab configuration from Config object
        return exchange -> {
            //grab the request
            ServerHttpRequest request = exchange.getRequest();
            //take information from the request to see if it
            //matches configuration.
            return matches(config, request);
        };
    }

    public static class Config {
        //Put the configuration properties for your filter here
    }

}

编写自定义网关过滤器工厂

要编写 GatewayFilter，你必须将 GatewayFilterFactory 实现为一个 bean。你可以扩展一个名为 AbstractGatewayFilterFactory 的抽象类。以下示例展示了如何做到这一点：

示例 1. PreGatewayFilterFactory.java

@Component
public class PreGatewayFilterFactory extends AbstractGatewayFilterFactory<PreGatewayFilterFactory.Config> {

	public PreGatewayFilterFactory() {
		super(Config.class);
	}

	@Override
	public GatewayFilter apply(Config config) {
		// grab configuration from Config object
		return (exchange, chain) -> {
			//If you want to build a "pre" filter you need to manipulate the
			//request before calling chain.filter
			ServerHttpRequest.Builder builder = exchange.getRequest().mutate();
			//use builder to manipulate the request
			return chain.filter(exchange.mutate().request(builder.build()).build());
		};
	}

	public static class Config {
		//Put the configuration properties for your filter here
	}

}

PostGatewayFilterFactory.java

@Component
public class PostGatewayFilterFactory extends AbstractGatewayFilterFactory<PostGatewayFilterFactory.Config> {

	public PostGatewayFilterFactory() {
		super(Config.class);
	}

	@Override
	public GatewayFilter apply(Config config) {
		// grab configuration from Config object
		return (exchange, chain) -> {
			return chain.filter(exchange).then(Mono.fromRunnable(() -> {
				ServerHttpResponse response = exchange.getResponse();
				//Manipulate the response in some way
			}));
		};
	}

	public static class Config {
		//Put the configuration properties for your filter here
	}

}

配置中自定义过滤器的命名和引用

自定义过滤器的类名应以 GatewayFilterFactory 结尾。

例如，要在配置文件中引用名为 Something 的过滤器，该过滤器必须在一个名为 SomethingGatewayFilterFactory 的类中。

也可以创建不带 GatewayFilterFactory 后缀的网关过滤器，例如 class AnotherThing。此过滤器可以在配置文件中被引用为 AnotherThing。这不是一种受支持的命名约定，此语法可能会在未来的版本中删除。请更新过滤器名称以符合规定。

编写自定义全局过滤器

要编写自定义全局过滤器，你必须将 GlobalFilter 接口实现为一个 bean。这会将过滤器应用于所有请求。

以下示例分别展示了如何设置全局前置和后置过滤器：

@Bean
public GlobalFilter customGlobalFilter() {
    return (exchange, chain) -> exchange.getPrincipal()
        .map(Principal::getName)
        .defaultIfEmpty("Default User")
        .map(userName -> {
          //adds header to proxied request
          ServerHttpRequest.Builder builder = exchange.getRequest().mutate().header("CUSTOM-REQUEST-HEADER", userName);
          //use builder to manipulate the request
          return exchange.mutate().request(builder.build()).build();
        })
        .flatMap(chain::filter);
}

@Bean
public GlobalFilter customGlobalPostFilter() {
    return (exchange, chain) -> chain.filter(exchange)
        .then(Mono.just(exchange))
        .map(serverWebExchange -> {
          //adds header to response
          serverWebExchange.getResponse().getHeaders().set("CUSTOM-RESPONSE-HEADER",
              HttpStatus.OK.equals(serverWebExchange.getResponse().getStatusCode()) ? "It worked": "It did not work");
          return serverWebExchange;
        })
        .then();
}