Spring Cloud Gateway网关中的过滤器

一、网关服务的搭建

Spring Cloud Gateway 和 nacos 不一样，我们必须自己搭建工程，首先创建一个新的 Spring Boot 项目

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>mall-parent</artifactId>
        <groupId>com.company</groupId>
        <version>1.0.0</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>mall-gateway</artifactId>

    <properties>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
    </properties>
    <dependencies>
        <!-- 网关 -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
        <!--nacos discovery-->
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <!--负载均衡-->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-loadbalancer</artifactId>
        </dependency>
    </dependencies>
    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

在配置文件 application.yaml 中编写路由规则

server:
  port: 8080
spring:
  application:
    name: gateway
  cloud:
    nacos:
      server-addr: 192.168.150.101:8848
    gateway:
      routes:
        - id: product                     # 路由规则id，自定义，唯一
          uri: lb://product-service       # 路由的目标服务，lb代表负载均衡，会从注册中心拉取服务列表
          predicates:                     # 路由断言，判断当前请求是否符合当前规则，符合则路由到目标服务
            - Path=/product/**,/search/** # 这里是以请求路径作为判断规则
        - id: cart
          uri: lb://cart-service
          predicates:
            - Path=/carts/**
          filters:                        # 在这里可以配置过滤器
            - AddRequestHeader=key, value # 逗号之前是HTTP请求头的key，逗号之后是value
        - id: user
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**

最后，启动项目即可

二、GatewayFilter 路由过滤器

@Component
public class PrintAnyGatewayFilterFactory extends AbstractGatewayFilterFactory<Object> {
    @Override
    public GatewayFilter apply(Object config) {
        return new GatewayFilter() {
            @Override
            public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
                // 获取请求
                ServerHttpRequest request = exchange.getRequest();
                // 编写过滤器逻辑
                System.out.println("过滤器执行了");
                // 放行
                return chain.filter(exchange);
            }
        };
    }
}

注意：该类的名称一定要以 GatewayFilterFactory 为后缀

三、GlobalFilter 全局过滤器

自定义GlobalFilter则简单很多，直接实现GlobalFilter即可，而且也无法设置动态参数

@Component
public class PrintAnyGlobalFilter implements GlobalFilter, Ordered {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 编写过滤器逻辑
        System.out.println("未登录，无法访问");
        // 放行
        // return chain.filter(exchange);

        // 拦截
        ServerHttpResponse response = exchange.getResponse();
        response.setRawStatusCode(401);
        return response.setComplete();
    }

    @Override
    public int getOrder() {
        // 过滤器执行顺序，值越小，优先级越高
        return 0;
    }
}