作者:codecraft

原文链接:https://segmentfault.com/a/1190000015282327

序

本文主要研究下spring cloud gateway的RedirectToGatewayFilter

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
    public RedirectToGatewayFilterFactory redirectToGatewayFilterFactory() {        return new RedirectToGatewayFilterFactory();
    }    //......}

RedirectToGatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC2-sources.jar!/org/springframework/cloud/gateway/filter/factory/RedirectToGatewayFilterFactory.java

public class RedirectToGatewayFilterFactory extends AbstractGatewayFilterFactory<RedirectToGatewayFilterFactory.Config> {    public static final String STATUS_KEY = "status";    public static final String URL_KEY = "url";    public RedirectToGatewayFilterFactory() {        super(Config.class);
    }    @Override
    public List<String> shortcutFieldOrder() {        return Arrays.asList(STATUS_KEY, URL_KEY);
    }    @Override
    public GatewayFilter apply(Config config) {        return apply(config.status, config.url);
    }    public GatewayFilter apply(String statusString, String urlString) {        final HttpStatus httpStatus = parse(statusString);
        Assert.isTrue(httpStatus.is3xxRedirection(), "status must be a 3xx code, but was " + statusString);        final URL url;        try {
            url = URI.create(urlString).toURL();
        } catch (MalformedURLException e) {            throw new IllegalArgumentException("Invalid url " + urlString, e);
        }        return apply(httpStatus, url);
    }    public GatewayFilter apply(HttpStatus httpStatus, URL url) {        return (exchange, chain) ->
            chain.filter(exchange).then(Mono.defer(() -> {                if (!exchange.getResponse().isCommitted()) {
                    setResponseStatus(exchange, httpStatus);                    final ServerHttpResponse response = exchange.getResponse();
                    response.getHeaders().set(HttpHeaders.LOCATION, url.toString());                    return response.setComplete();
                }                return Mono.empty();
            }));
    }    public static class Config {
        String status;
        String url;        public String getStatus() {            return status;
        }        public void setStatus(String status) {            this.status = status;
        }        public String getUrl() {            return url;
        }        public void setUrl(String url) {            this.url = url;
        }
    }

}

• 可以看到配置文件有两个参数，一个是status，一个是url

• 这里对status进行了校验，必须是3xx

• 然后设置response status code，同时在header的location写入要跳转的url

实例

spring:  cloud:    gateway:      routes:      - id: prefixpath_route        uri: http://example.org        filters:        - RedirectTo=302, http://acme.org

小结

spring cloud gateway提供了RedirectToGatewayFilter，可以直接在配置文件对指定的路由进行3xx跳转。

doc

• 112.8 RedirectTo GatewayFilter Factory