Java大数据

Spring Cloud Gateway自定义过滤器实战(观测断

2021-11-22  本文已影响0人  Java弟中弟

套路提前知晓

  1. 新建一个类（我这里名为StatePrinterGatewayFilter.java），实现GatewayFilter和Ordered接口，重点是filter方法，该过滤器的主要功能就在这里面实现
  2. 新建一个类（我这里名为StatePrinterGatewayFilterFactory.java），实现AbstractGatewayFilterFactory方法，其apply方法的返回值就是上一步新建的StatePrinterGatewayFilter的实例，该方法的入参是在路由配置中过滤器节点下面的配置，这样就可以根据配置做一些特殊的处理，然后再创建实例作为返回值
  3. StatePrinterGatewayFilterFactory类实现String name()方法，该方法的返回值就是路由配置文件中过滤器的name
  4. String name()也可以不实现，这是因为定义该方法的接口中有默认实现了，如下图，这样您在路由配置文件中过滤器的name只能是StatePrinter：
  1. 在配置文件中，添加您自定义的过滤器，该操作和之前的添加内置过滤器一模一样

如何取得断路器的状态

@Configuration
public class CustomizeCircuitBreakerConfig {

    @Bean
    public ReactiveResilience4JCircuitBreakerFactory defaultCustomizer() {

        CircuitBreakerConfig circuitBreakerConfig = CircuitBreakerConfig.custom() //
                .slidingWindowType(CircuitBreakerConfig.SlidingWindowType.TIME_BASED) // 滑动窗口的类型为时间窗口
                .slidingWindowSize(10) // 时间窗口的大小为60秒
                .minimumNumberOfCalls(5) // 在单位时间窗口内最少需要5次调用才能开始进行统计计算
                .failureRateThreshold(50) // 在单位时间窗口内调用失败率达到50%后会启动断路器
                .enableAutomaticTransitionFromOpenToHalfOpen() // 允许断路器自动由打开状态转换为半开状态
                .permittedNumberOfCallsInHalfOpenState(5) // 在半开状态下允许进行正常调用的次数
                .waitDurationInOpenState(Duration.ofSeconds(5)) // 断路器打开状态转换为半开状态需要等待60秒
                .recordExceptions(Throwable.class) // 所有异常都当作失败来处理
                .build();

        ReactiveResilience4JCircuitBreakerFactory factory = new ReactiveResilience4JCircuitBreakerFactory();
        factory.configureDefault(id -> new Resilience4JConfigBuilder(id)
                .timeLimiterConfig(TimeLimiterConfig.custom().timeoutDuration(Duration.ofMillis(200)).build())
                .circuitBreakerConfig(circuitBreakerConfig).build());

        return factory;
    }
}

源码下载

编码

package com.bolingcavalry.circuitbreakergateway.filter;

import io.github.resilience4j.circuitbreaker.CircuitBreaker;
import io.github.resilience4j.circuitbreaker.CircuitBreakerRegistry;
import io.vavr.collection.Seq;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.circuitbreaker.resilience4j.ReactiveResilience4JCircuitBreakerFactory;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;
import java.lang.reflect.Method;

public class StatePrinterGatewayFilter implements GatewayFilter, Ordered {

    private ReactiveResilience4JCircuitBreakerFactory reactiveResilience4JCircuitBreakerFactory;

    // 通过构造方法取得reactiveResilience4JCircuitBreakerFactory实例
    public StatePrinterGatewayFilter(ReactiveResilience4JCircuitBreakerFactory reactiveResilience4JCircuitBreakerFactory) {
        this.reactiveResilience4JCircuitBreakerFactory = reactiveResilience4JCircuitBreakerFactory;
    }

    private CircuitBreaker circuitBreaker = null;

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 这里没有考虑并发的情况，如果是生产环境，请您自行添加上锁的逻辑
        if (null==circuitBreaker) {
            CircuitBreakerRegistry circuitBreakerRegistry = null;
            try {
                Method method = reactiveResilience4JCircuitBreakerFactory.getClass().getDeclaredMethod("getCircuitBreakerRegistry",(Class[]) null);
                // 用反射将getCircuitBreakerRegistry方法设置为可访问
                method.setAccessible(true);
                // 用反射执行getCircuitBreakerRegistry方法，得到circuitBreakerRegistry
                circuitBreakerRegistry = (CircuitBreakerRegistry)method.invoke(reactiveResilience4JCircuitBreakerFactory);
            } catch (Exception exception) {
                exception.printStackTrace();
            }

            // 得到所有断路器实例
            Seq<CircuitBreaker> seq = circuitBreakerRegistry.getAllCircuitBreakers();
            // 用名字过滤，myCircuitBreaker来自路由配置中
            circuitBreaker = seq.filter(breaker -> breaker.getName().equals("myCircuitBreaker"))
                    .getOrNull();
        }

        // 取断路器状态，再判空一次，因为上面的操作未必能取到circuitBreaker
        String state = (null==circuitBreaker) ? "unknown" : circuitBreaker.getState().name();

        System.out.println("state : " + state);

        // 继续执行后面的逻辑
        return chain.filter(exchange);
    }

    @Override
    public int getOrder() {
        return 10;
    }
}

package com.bolingcavalry.circuitbreakergateway.filter;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.circuitbreaker.resilience4j.ReactiveResilience4JCircuitBreakerFactory;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
import org.springframework.stereotype.Component;

@Component
public class StatePrinterGatewayFilterFactory extends AbstractGatewayFilterFactory<Object>
{
    @Autowired
    ReactiveResilience4JCircuitBreakerFactory reactiveResilience4JCircuitBreakerFactory;

    @Override
    public String name() {
        return "CircuitBreakerStatePrinter";
    }

    @Override
    public GatewayFilter apply(Object config)
    {
        return new StatePrinterGatewayFilter(reactiveResilience4JCircuitBreakerFactory);
    }
}

server:
  #服务端口
  port: 8081
spring:
  application:
    name: circuitbreaker-gateway
  cloud:
    gateway:
      routes:
        - id: path_route
          uri: http://127.0.0.1:8082
          predicates:
            - Path=/hello/**
          filters:
            - name: CircuitBreaker
              args:
                name: myCircuitBreaker
            - name: CircuitBreakerStatePrinter

分析请求被filter漏掉的问题

再次修改

server:
  #服务端口
  port: 8081
spring:
  application:
    name: circuitbreaker-gateway
  cloud:
    gateway:
      routes:
        - id: path_route
          uri: http://127.0.0.1:8082
          predicates:
            - Path=/hello/**
          filters:
            - name: CircuitBreakerStatePrinter
            - name: CircuitBreaker
              args:
                name: myCircuitBreaker

知识点小结

  1. 常规的局部过滤器开发步骤
  2. 过滤器执行顺序的逻辑
  3. spring的依赖注入和自动装配
  4. 断路器的filter源码
  5. java的反射基本功
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