SpringCloud gateway内置过滤器之一

1、AddRequestHeader GatewayFilter

AddRequestHeader GatewayFilter采用名称和值参数。例如：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/**
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, blue

此列表将X-Request-red:blue标头添加到所有匹配请求的下游请求标头中。

Producer服务的controller：

@RequestMapping("/hello")
public String hello(String name, HttpServletRequest request) {
    System.out.println(request.getHeader("x-request-red"));
    return "hello," + name + "," + port;
}

访问http://localhost:8500/producer/hello，看到
 

 

AddRequestHeader也用于匹配路径或主机的URI变量：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, Blue-{segment}

访问http://localhost:8500/producer/hello，看到
 

 

2、AddRequestParameter GatewayFilter

AddRequestParameter GatewayFilter采用名称和值参数。例如：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, Blue-{segment}
              - AddRequestParameter=red, blue

这将为所有匹配请求的下游请求的查询字符串添加red=blue。

 

Producer服务controller：

@RequestMapping("/hello")
public String hello(String name, HttpServletRequest request) {
    System.out.println(request.getHeader("x-request-red"));
    System.out.println(request.getParameter("red"));
    return "hello," + name + "," + port;
}

访问http://localhost:8500/producer/hello，看到
 

 

AddRequestParameter也用于匹配路径或主机的URI变量：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, Blue-{segment}
              - AddRequestParameter=red, bar-{segment}

访问http://localhost:8500/producer/hello，看到
 

 

3、AddResponseHeader GatewayFilter

AddResponseHeader GatewayFilter采用名称和值参数。这会将响应头添加到所有匹配请求的下游响应标头中。例如：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddResponseHeader=X-Response-Red, Blue

访问http://localhost:8500/producer/hello，从浏览器控制台中可看到响应头：
 

 
AddResponseHeader也用于匹配路径或主机的URI变量：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddResponseHeader=X-Response-Red, Blue-{segment}

访问http://localhost:8500/producer/hello，从浏览器控制台中可看到响应头：
 

 

4、DedupeResponseHeader GatewayFilter

DedupeResponseHeader GatewayFilter采用名称参数和可选策略参数。name可以包含一个以空格分隔的标头名称列表。例如：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin

将删除Access-Control-Allow-Credentials和Access-Control-Allow-Origin头的重复值。

5、Spring Cloud CircuitBreaker GatewayFilter

Spring Cloud CircuitBreaker GatewayFilter工厂使用Spring Cloud CircutBreaker API将网关路由封装在断路器中。Spring Cloud CircuitBreaker支持可与Spring Cloud Gateway一起使用的多个库。Spring Cloud支持开箱即用的Resilience4J。在GatewayServer模块加入依赖：

<dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
    </dependency>

并添加controller：

@RestController
public class Fallback {

    private String dateStr(){
        return new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date());
    }

    /**
     * 返回字符串类型
     * @return
     */
    @GetMapping("/myfallback")
    public String helloStr() {
        return "myfallback, " + dateStr();
    }
}

在application.yml配置：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - name: CircuitBreaker
                args:
                    name: myCircuitBreaker
                    fallbackUri: forward:/myfallback

fallbackUri中的url要和上面controller中的url相同。当出现异常时会转发到fallbackUri。现在关闭Producer服务，访问http://localhost:8500/producer/hello，看到myfallback, 2023-05-04 08:27:53。

 

也可以根据响应状态码列表来触发熔断开关。可以配置响应状态码，也可以配置HttpStatus枚举。例如：

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, Blue-{segment}
              - AddRequestParameter=red, bar-{segment}
              - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin
              - name: CircuitBreaker
                args:
                    name: myCircuitBreaker
                    fallbackUri: forward:/myfallback
                    statusCodes:
                      - 500

修改Producer的controller：

 @RequestMapping("/hello")
public String hello(String name, HttpServletRequest request, HttpServletResponse response) {
    System.out.println(request.getHeader("x-request-red"));
    System.out.println(request.getParameter("red"));
    response.setStatus(500);
    return "hello," + name + "," + port;
}

访问http://localhost:8500/producer/hello，看到myfallback, 2023-05-04 08:48:07。将response.setStatus(500);改成response.setStatus(404);重新访问http://localhost:8500/producer/hello，看到hello,null,8002。

修改gateway的application.yml配置

spring:
  cloud:
    gateway:
      enabled: true
      routes:
        - id: Goods-Server  # 路由 id，唯一标识
          uri: lb://producer
          predicates:
            #  - Path=/**  # 断言，路由匹配条件，匹配 /product 开头的所有 api
              - Path=/producer/{segment}
          filters:
              - StripPrefix=1
              - AddRequestHeader=X-Request-red, Blue-{segment}
              - AddRequestParameter=red, bar-{segment}
              - DedupeResponseHeader=Access-Control-Allow-Credentials Access-Control-Allow-Origin
              - name: CircuitBreaker
                args:
                    name: myCircuitBreaker
                    fallbackUri: forward:/myfallback
                    statusCodes:
                      - 500
                      - "NOT_FOUND"

重新访问http://localhost:8500/producer/hello，看到myfallback, 2023-05-04 08:50:27。