Spring Boot中集成Spring Cloud Gateway的斷言和過濾器

在Spring Boot中集成Spring Cloud Gateway，可以通過配置斷言（Predicates）和過濾器（Filters）來實現自定義的路由規則和請求處理邏輯。以下是一個簡單的示例，展示了如何配置斷言和過濾器。

1. 添加依賴

首先，在你的pom.xml文件中添加Spring Cloud Gateway和Spring Boot的依賴：

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

2. 配置文件

在你的application.yml或application.properties文件中配置路由規則、斷言和過濾器。

application.yml

spring:
  cloud:
    gateway:
      routes:
        - id: example_route
          uri: http://example.org
          predicates:
            - Path=/api/**
          filters:
            - name: AddRequestHeader
              args:
                key: X-Request-Id
                value: ${random.value}
            - name: LogRequest
              args:
                loggerName: org.springframework.cloud.gateway.filter.GatewayFilterChain

application.properties

spring.cloud.gateway.routes.example_route.uri=http://example.org
spring.cloud.gateway.routes.example_route.predicates.0.Path=/api/**
spring.cloud.gateway.routes.example_route.filters.0.name=AddRequestHeader
spring.cloud.gateway.routes.example_route.filters.0.args.key=X-Request-Id
spring.cloud.gateway.routes.example_route.filters.0.args.value=${random.value}
spring.cloud.gateway.routes.example_route.filters.1.name=LogRequest
spring.cloud.gateway.routes.example_route.filters.1.args.loggerName=org.springframework.cloud.gateway.filter.GatewayFilterChain

3. 自定義斷言和過濾器

你可以創建自定義的斷言和過濾器來滿足特定的需求。

自定義斷言

創建一個自定義斷言類：

import org.springframework.cloud.gateway.filter.ratelimit.KeyResolver;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Configuration
public class CustomAssertionConfig {

    @Bean
    public KeyResolver userKeyResolver() {
        return new KeyResolver() {
            @Override
            public Mono<String> resolve(ServerWebExchange exchange) {
                return Mono.just(exchange.getRequest().getHeaders().getFirst("User-Id"));
            }
        };
    }
}

自定義過濾器

創建一個自定義過濾器類：

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

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

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

    @Override
    public GatewayFilter apply(Config config) {
        return (exchange, chain) -> {
            // 自定義過濾邏輯
            System.out.println("Custom filter applied");
            return chain.filter(exchange);
        };
    }

    public static class Config {
        // 配置參數
    }
}

4. 配置自定義斷言和過濾器

在你的路由配置中引用自定義斷言和過濾器：

application.yml

spring:
  cloud:
    gateway:
      routes:
        - id: example_route
          uri: http://example.org
          predicates:
            - Path=/api/**
          filters:
            - name: AddRequestHeader
              args:
                key: X-Request-Id
                value: ${random.value}
            - name: CustomFilter
              args: {}

application.properties

spring.cloud.gateway.routes.example_route.uri=http://example.org
spring.cloud.gateway.routes.example_route.predicates.0.Path=/api/**
spring.cloud.gateway.routes.example_route.filters.0.name=AddRequestHeader
spring.cloud.gateway.routes.example_route.filters.0.args.key=X-Request-Id
spring.cloud.gateway.routes.example_route.filters.0.args.value=${random.value}
spring.cloud.gateway.routes.example_route.filters.1.name=CustomFilter

通過以上步驟，你可以在Spring Boot中集成Spring Cloud Gateway，并配置自定義的斷言和過濾器。