spring cloud學習(四) 動態路由

Zuul的主要功能是路由和過濾器。路由功能是微服務的一部分，zuul實現了負載均衡。

1.1
新建模塊zuul
pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>spring-cloud</artifactId>
        <groupId>com.feng</groupId>
        <version>0.0.1</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>zuul</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
        </dependency>
    </dependencies>

</project>

1.2
application.yml:

spring:
  application:
    name: zuul

server:
  port: 8020

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8010/eureka/

zuul:
  routes:
    api-a:
      path: /service-a/**
      serviceId: service-a
    api-b:
      path: /service-b/**
      serviceId: service-b
  sensitive-headers:  #設置忽略的頭信息，設置為空能解決會話保持問題
  add-host-header: true #設為true才能保持Host頭信息處理正確

上面配置說明把/service-a/開頭的所有請求都轉發給service-a服務執行，把/service-b/開頭的所有請求都轉發給service-b服務執行

1.3
ZuulApplication，使用EnableZuulProxy注解開啟zuul功能，並且注冊了一個zuul的過濾器

/**
 * @author fengzp
 * @date 17/4/27
 * @email [e-mail]
 * @company 廣州易站通計算機科技有限公司
 */
@SpringCloudApplication //這個注解整合了@SpringBootApplication、@EnableDiscoveryClient、@EnableCircuitBreake
@EnableZuulProxy
public class ZuulApplication {

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

    @Bean
    public MyZuulFilter getZuulFilter(){
        return new MyZuulFilter();
    }
}

MyZuulFilter，過濾器加了個判斷id是否為空，空則返回401錯誤碼

public class MyZuulFilter extends ZuulFilter {

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

    /**
     * 返回過濾器類型
     * @return
     *  pre：可以在請求被路由之前調用
     *  routing：在路由請求時候被調用
     *  post：在routing和error過濾器之后被調用
     *  error：處理請求時發生錯誤時被調用
     */
    @Override
    public String filterType() {
        return "pre";
    }

    /**
     * 通過int值來定義過濾器的執行順序
     */
    @Override
    public int filterOrder() {
        return 0;
    }

    /**
     * 判斷過濾器是否執行
     */
    @Override
    public boolean shouldFilter() {
        return true;
    }

    /**
     * 過濾器的具體邏輯
     *  ctx.setSendZuulResponse(false)令zuul不允許請求，
     *  ctx.setResponseStatusCode(401)設置了其返回的錯誤碼
     *  ctx.setResponseBody(body)編輯返回body內容
     * @return
     */
    @Override
    public Object run() {
        RequestContext ctx = RequestContext.getCurrentContext();

        HttpServletRequest request = ctx.getRequest();

        log.info(String.format("%s request to %s", request.getMethod(), request.getRequestURL().toString()));
        Object accessToken = request.getParameter("id");
        if(accessToken == null) {
            log.warn("id is null");
            ctx.setSendZuulResponse(false);
            ctx.setResponseStatusCode(401);
            return null;
        }

        log.info("pass!");
        return null;
    }

}

1.4

把之前負載的service-b的spring.application.name改為service-b, 運行項目，分別打開http://localhost:8020/service-a/hi?id=zuul和http://localhost:8020/service-b/hi?id=zuul