SpringCloud之Zuul

1、简介

Zuul是Netflix开源的微服务网关，可以和Eureka、Ribbon、Hystrix等组件配合使用，Spring Cloud对Zuul进行了整合与增强，Zuul默认使用的HTTP客户端是Apache HTTPClient，也可以使用RestClient或okhttp3.OkHttpClient。 Zuul的主要功能是路由转发和过滤器。路由功能是微服务的一部分。zuul默认和Ribbon结合实现了负载均衡的功能

2、贴代码

（1）、pom依赖

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Finchley.SR2</spring-cloud.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-eureka</artifactId>
        <version>1.4.0.RELEASE</version>
    </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>

    <!-- 配置hystrix所需依赖的包 -->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        <version>1.4.7.RELEASE</version>
    </dependency>
</dependencies>
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${spring-cloud.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

（2）、application.properties

spring.application.name=springbootZuul
server.port=6005
eureka.client.service-url.defaultZone=http://localhost:5000/eureka/

zuul.routes.springbootService.path=/springbootService/**
zuul.routes.springbootService.serviceId=springbootService

zuul.routes.springCloudFeign.path=/springCloudFeign/**
zuul.routes.springCloudFeign.serviceId=springCloudFeign

（3）、主方法入口

@SpringBootApplication
@EnableDiscoveryClient
@EnableZuulProxy
@RefreshScope
public class ZuulserviceApplication {

    public static void main(String[] args) {
        SpringApplication.run(ZuulserviceApplication.class, args);
    }

}

（4）、请求过滤

@Component
public class serviceFilter extends ZuulFilter {

    private static Logger log = LoggerFactory.getLogger(serviceFilter.class);

    @Override
    public String filterType() {
        return "pre"; // 定义filter的类型，有pre、route、post、error四种
    }

    @Override
    public int filterOrder() {
        return 0; // 定义filter的顺序，数字越小表示顺序越高，越先执行
    }

    @Override
    public boolean shouldFilter() {
        return true; // 表示是否需要执行该filter，true表示执行，false表示不执行
    }

    @Override
    public Object run() {
        // filter需要执行的具体操作
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest request = ctx.getRequest();
        String token = request.getParameter("token");
        System.out.println(token);
        if (token == null) {
            log.warn("there is no request token");
            ctx.setSendZuulResponse(false);
            ctx.setResponseStatusCode(401);
            try {
                ctx.getResponse().getWriter().write("there is no request token");
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }
        log.info("ok");
        return null;
    }
}

（5）、失败回调

@Component
public class ServiceFallbackProvider implements FallbackProvider {
    @Override
    // 指定熔断器功能应用于哪些路由的服务
    public String getRoute() {
        // 这里只针对"springbootService"服务进行熔断
        // 如果需要针对所有服务熔断，则return "*"
        return "springbootService";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        System.out.println("route:"+route);

        return new ClientHttpResponse() {
            @Override
            public HttpStatus getStatusCode() throws IOException {
                return HttpStatus.OK;
            }

            @Override
            public int getRawStatusCode() throws IOException {
                return 200;
            }

            @Override
            public String getStatusText() throws IOException {
                return "ok";
            }

            @Override
            public void close() {

            }

            @Override
            // 发生熔断式，返回的信息
            public InputStream getBody() throws IOException {
                return new ByteArrayInputStream("Sorry, the service is unavailable now.".getBytes());
            }

            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders headers = new HttpHeaders();
                headers.setContentType(MediaType.APPLICATION_JSON);
                return headers;
            }
        };
    }
}

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