网关简绍

就是网络的关口，负责请求的路由、转发、身份校验。

引入网关依赖

 <dependencies>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-gateway</artifactId>
	</dependency>
	<dependency>
		<groupId>com.alibaba.cloud</groupId>
		<artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
	</dependency>
	<dependency>
		<groupId>org.springframework.cloud</groupId>
		<artifactId>spring-cloud-starter-loadbalancer</artifactId>
	</dependency>
</dependencies>

配置路由规则

• id： 路由唯一标示
• uri: 路由目标地址
• predicates: 路由断言，判断请求是否符合当前路由
• filters: 路由过滤器，对请求或响应做特殊处理

spring:
  application:
    name: hm-gateway
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
    gateway:
      routes:
        - id: item-service # 路由的规则id， 自定义唯一
          uri: lb://item-service # 路由服务目标 lb 代表负载均衡
          predicates: # 路由断言, 判断路径是否符合规则。符合则路由到目标路径
            - Path=/items/**,/search/** # 以请求路径做判断， 以/items 开头则符合
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**

更多规则的路由断言

路由过滤器

使用 路由过滤器, 配置 AddRequestHeader 添加请求头

server:
  port: 8080

spring:
  application:
    name: hm-gateway
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
    gateway:
      routes:
        - id: item-service
          uri: lb://item-service
          predicates:
            - Path=/items/**,/search/**
          filters:
            - AddRequestHeader=truth, anyone long-press like button will be rich
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**

使用 @RequestHeader(value = “truth”, required = false)String truth 获取

public void test(@RequestHeader(value = "truth", required = false)String truth) {
        System.out.println("truth" + truth);
}

可以配置全局 默认过滤器, 使用 default-filters 与 routes 同级

server:
  port: 8080

spring:
  application:
    name: hm-gateway
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
    gateway:
      routes:
        - id: item-service
          uri: lb://item-service
          predicates:
            - Path=/items/**,/search/**
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**
      default-filters:
        - AddRequestHeader=truth, anyone long-press like button will be rich

自定义过滤器

• GatewayFilter：路由过滤器，作用于任意指定的路由；默认不生效，要配置到路由后生效。
• GlobalFilter：全局过滤器，作用范围是所有路由；声明后自动生效。

过滤器处理流程

两种过滤器的过滤方法签名完全一致：

• ServerWebExchange 请求上下文， 包含整个过滤器链中共享数据
• GatewayFilterChain 过滤器链。当前过滤器执行完后，要调用过滤器链中的下一个过滤器

Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);

GlobalFilter过滤器

定义Ordered 用来定义启动顺序全局执行过滤器, 实现 filter 来进行过滤信息

@Component
public class MyGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        ServerHttpRequest request = exchange.getRequest();
        System.out.println("GlobalFilter pre阶段 执行了。");
        return chain.filter(exchange);
    }

    @Override
    public int getOrder() {
        return 0;
    }
}

GatewayFilter过滤器

自定义过滤器， 需要在配置文件中主动配置才能去调用， 同样也是实现 filter 来进行过滤的

@Component
public class PrintAnyGatewayFilterFactory  extends AbstractGatewayFilterFactory {
    @Override
    public GatewayFilter apply(Object config) {
        // 使用内部装饰类，定义启动顺序
        return new OrderedGatewayFilter(new GatewayFilter() {
            @Override
            public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
                System.out.println("PrintAnyGateway 执行了");
                return chain.filter(exchange);
            }
        }, 1);
    }
}

具体配置文件

server:
  port: 8080

spring:
  application:
    name: hm-gateway
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
    gateway:
      routes:
        - id: item-service
          uri: lb://item-service
          predicates:
            - Path=/items/**,/search/**
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**
      default-filters:
        - AddRequestHeader=truth, anyone long-press like button will be rich
        - PrintAny

定义过滤器读取参数信息

server:
  port: 8080

spring:
  application:
    name: hm-gateway
  cloud:
    nacos:
      server-addr: 127.0.0.1:8848
    gateway:
      routes:
        - id: item-service
          uri: lb://item-service
          predicates:
            - Path=/items/**,/search/**
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/users/**,/addresses/**
      default-filters:
        - AddRequestHeader=truth, anyone long-press like button will be rich
        - PrintAny=1,2,3

从过滤器取 1，2，3, 配置全局 PrintAnyGatewayFilterFactory 将 Config 委托给父类， 使用 shortcutFieldOrder 按顺序取读取信息

@Component
public class PrintAnyGatewayFilterFactory  extends AbstractGatewayFilterFactory<PrintAnyGatewayFilterFactory.Config> {
    @Override
    public GatewayFilter apply(Config config) {
        // 使用内部装饰类，定义启动顺序
        return new OrderedGatewayFilter(new GatewayFilter() {
            @Override
            public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
                String a = config.getA();
                String b = config.getB();
                String c = config.getC();
                System.out.println(a + b + c);
                System.out.println("PrintAnyGateway 执行了");
                return chain.filter(exchange);
            }
        }, 1);
    }

    @Data
    public static class Config{
        private String a;
        private String b;
        private String c;
    }

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

    @Override
    public List<String> shortcutFieldOrder() {
        return List.of("a", "b", "c");
    }
}