Spring Cloud 学习纪要七：Zuul

悠悠 2022-04-14 07:00 223阅读 0赞

## Spring Cloud Zuul：统一网关 ##

Spring Cloud Zuul 提供动态路由，监控，弹性，安全等边缘服务，将细粒度的服务组合起来提供一个粗粒度的服务，所有请求都导入一个统一的入口，那么整个系统只需要暴露一个服务，对外屏蔽服务端实现细节，这样也减少了客户端与服务器的网络调用次数，这就是api gateway，也是Zuul可以帮我们实现的功能。

<table> 
 <thead> 
  <tr> 
   <th>开发环境</th> 
   <th>版本</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>IDEA</td> 
   <td>2018.2.6</td> 
  </tr> 
  <tr> 
   <td>JDK</td> 
   <td>1.8</td> 
  </tr> 
  <tr> 
   <td>Spring Boot</td> 
   <td>2.0.6</td> 
  </tr> 
  <tr> 
   <td>Spring Cloud</td> 
   <td>Finchley.SR2</td> 
  </tr> 
 </tbody> 
</table>

> **特别注意**：本系列纪要环环相扣，建议从第一节开始阅读 [点击跳转][Link 1]

### 路由 ###

#### 新建项目zuul ####

Maven依赖：

<dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-zuul</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

配置文件（可以参照前几章内容将配置放到git仓库）：

eureka:
      client:
        service-url:
          defaultZone: http://localhost:8761/eureka/,http://localhost:8762/eureka/
      instance:
        prefer-ip-address: true
        instance-id: ${ spring.cloud.client.ip-address}:${ server.port}
        # hostname: ZuulName
    
    spring:
      application:
        name: zuul
      cloud:
        config:
          discovery:
            enabled: true
            service-id: config
          profile: dev

启动类添加@EnableZuulProxy注解：

@SpringBootApplication
    @EnableZuulProxy
    public class ZuulApplication { 
        public static void main(String[] args) { 
            SpringApplication.run(ZuulApplication.class, args);
        }
    }

在前面几章的项目均已启动的前提下，将zuul项目VM options设置\-DServer.port=8061，运行成功后访问[http://localhost:8061/provider/hello/chung][http_localhost_8061_provider_hello_chung]，发现zuul会自动将请求路由至provider服务。

> 此路径中得到provider为serviceId

#### 自定义路由 ####

进行如下配置，运行成功后访问[http://localhost:8061/myRoute/hello/chung][http_localhost_8061_myRoute_hello_chung]，zuul也会自动将请求路由至provider服务。

zuul:
      routes:
        provider: /myRoute/**

### PRE\_TYPE Zuul Filter ###

前置过滤器可以实现限流、鉴权、参数校验等功能。

#### 鉴权、参数校验 ####

@Component
    public class PreFilter extends ZuulFilter { 
        @Override
        public String filterType() { 
            return PRE_TYPE;
        }
    
        @Override
        public int filterOrder() { 
            return PRE_DECORATION_FILTER_ORDER - 1;
        }
    
        @Override
        public boolean shouldFilter() { 
            return true;
        }
    
        @Override
        public Object run() { 
            RequestContext currentContext = RequestContext.getCurrentContext();
            HttpServletRequest request = currentContext.getRequest();
    
            // 鉴权
            if ("/provider/hello/send".equals(request.getRequestURI())) { 
                if (false) { 
                    currentContext.setSendZuulResponse(false);
                    currentContext.setResponseStatusCode(HttpStatus.SC_UNAUTHORIZED);
                }
            }
    
            // 参数校验
            if (StringUtils.isEmpty(request.getParameter("token"))) { 
                currentContext.setSendZuulResponse(false);
                currentContext.setResponseStatusCode(HttpStatus.SC_UNAUTHORIZED);
            }
            return null;
        }
    }

#### API限流 ####

使用令牌桶算法，Google的RateLimiter工具。

@Component
    public class RateLimitFilter extends ZuulFilter { 
        private static final RateLimiter RATE_LIMITER = RateLimiter.create(100);
    
        @Override
        public String filterType() { 
            return PRE_TYPE;
        }
    
        @Override
        public int filterOrder() { 
            return SERVLET_DETECTION_FILTER_ORDER - 1;
        }
    
        @Override
        public boolean shouldFilter() { 
            return true;
        }
    
        @Override
        public Object run() { 
            if (!RATE_LIMITER.tryAcquire()) { 
                RequestContext currentContext = RequestContext.getCurrentContext();
                currentContext.setSendZuulResponse(false);
                currentContext.setResponseStatusCode(HttpStatus.SC_SERVICE_UNAVAILABLE);
            }
            return null;
        }
    }

### POST\_TYPE Zuul Filter ###

后置过滤器可以实现统计、日志记录等功能。

@Component
    public class PostFilter extends ZuulFilter { 
    
        @Override
        public String filterType() { 
            return POST_TYPE;
        }
    
        @Override
        public int filterOrder() { 
            return SEND_RESPONSE_FILTER_ORDER - 1;
        }
    
        @Override
        public boolean shouldFilter() { 
            return true;
        }
    
        @Override
        public Object run() { 
            RequestContext currentContext = RequestContext.getCurrentContext();
            HttpServletResponse response = currentContext.getResponse();
            /**Some Code**/
            response.setHeader("POST_HEADER", UUID.randomUUID().toString());
            return null;
        }
    }

**附件**

> 本系列纪要博客源码：[跳转到github][github]  
> 本系列纪要博客配置文件：[跳转到github][github 1]

[Link 1]: https://blog.csdn.net/u012102104/article/details/84286472
[http_localhost_8061_provider_hello_chung]: http://localhost:8061/provider/hello/chung
[http_localhost_8061_myRoute_hello_chung]: http://localhost:8061/myRoute/hello/chung
[github]: https://github.com/chung567115/SpringCloud
[github 1]: https://github.com/chung567115/SpringCloudConfig