`AddRequestHeadersIfNotPresent` 过滤器

AddRequestHeadersIfNotPresent 过滤器接受由冒号分隔的 `名称` 和 `值` 对集合。以下示例配置了一个 `AddRequestHeadersIfNotPresent` 过滤器

application.yml

spring:
  cloud:
    gateway:
      mvc:
        routes:
        - id: add_request_headers_route_inp
          uri: https://example.org
          predicates:
          - Path=/red
          filters:
          - AddRequestHeadersIfNotPresent=X-Request-Color-1:blue,X-Request-Color-2:green

GatewaySampleApplication.java

import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.uri;
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.addRequestHeadersIfNotPresent;
import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

@Configuration
class RouteConfiguration {

    @Bean
    public RouterFunction<ServerResponse> gatewayRouterFunctionsAddReqHeaderInp() {
        return route("add_request_headers_route_inp")
            .GET("/red", http())
            .before(uri("https://example.org"))
            .before(addRequestHeadersIfNotPresent("X-Request-Color-1:blue","X-Request-Color-2:green"));
    }
}

此列表为所有匹配的请求向下游请求的头部添加了两个头部 X-Request-Color-1:blue 和 X-Request-Color-2:green。这类似于 AddRequestHeader 的工作方式，但与 AddRequestHeader 不同的是，它只会在头部尚不存在时添加。否则，将发送客户端请求中的原始值。

此外，要设置一个多值头部，可以多次使用头部名称，例如 addRequestHeadersIfNotPresent("X-Request-Color-1:blue","X-Request-Color-1:green")。

AddRequestHeadersIfNotPresent 也支持用于匹配路径或主机的 URI 变量。URI 变量可以在值中使用，并在运行时展开。以下示例配置了一个使用变量的 AddRequestHeadersIfNotPresent 过滤器

GatewaySampleApplication.java

import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.addRequestHeadersIfNotPresent;
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.uri;
import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

@Configuration
class RouteConfiguration {

    @Bean
    public RouterFunction<ServerResponse> gatewayRouterFunctionsAddReqHeaderInp() {
        return route("add_request_header_route_inp")
            .GET("/red/{segment}", http())
            .before(uri("https://example.org"))
            .before(addRequestHeadersIfNotPresent("X-Request-red", "blue-{segment}"));
    }
}

application.yml

spring:
  cloud:
    gateway:
      routes:
      - id: add_request_header_route_inp
        uri: https://example.org
        predicates:
        - Path=/red/{segment}
        filters:
        - AddRequestHeadersIfNotPresent=X-Request-Red:Blue-{segment}

AddRequestHeadersIfNotPresent 过滤器

`AddRequestHeadersIfNotPresent` 过滤器