关于后端:Zuul

作用

API网关

• 后盾服务对立的调用入口
• 转发的路由规定如下:

zuul:
 routes:
 # 近程服务: 调用门路
 # 上面配置的是默认规定，不配置也能够主动配置
 # 如果不配置，能够依据注册表主动配置

实现步骤

1.增加依赖:Zuul/eureka client
2.配置application.yml:application.name/server.port/zuul.route.服务

spring:
  application:
    name: zuul
    
server:
  port: 3001
  
eureka:
  client:
    service-url:
      defaultZone: http://eureka1:2001/eureka, http://eureka2:2002/eureka

zuul:
  routes:
    item-service: /item-service/**
    user-service: /user-service/**
    order-service: /order-service/**

3.启动类增加注解@EnableZuulProxy

@EnableZuulProxy
@SpringBootApplication
public class Sp11ZuulApplication {
    public static void main(String[] args) {
        SpringApplication.run(Sp11ZuulApplication.class, args);
    }
}

对立的权限校验

定义过滤器

通过继承 ZuulFilter 过滤器，来实现权限判断
没登陆就阻止拜访
已登录就容许拜访–http://…/…?token=…

@Component
public class AccessFilter extends ZuulFilter{
    //是否执行过滤代码
    @Override
    public boolean shouldFilter() {
        //对指定的serviceid过滤，如果要过滤所有服务，间接返回 true
        
        RequestContext ctx = RequestContext.getCurrentContext();
        String serviceId = (String) ctx.get(FilterConstants.SERVICE_ID_KEY);
        if(serviceId.equals("item-service")) {
            return true;
        }
        return false;
    }

    //过滤代码
    @Override
    public Object run() throws ZuulException {
        RequestContext ctx = RequestContext.getCurrentContext();
        HttpServletRequest req = ctx.getRequest();
        String token = req.getParameter("token");
        if (token == null) {
            //此设置会阻止申请被路由到后盾微服务
            ctx.setSendZuulResponse(false);
            //向客户端的响应
            ctx.setResponseStatusCode(200);
            ctx.setResponseBody(JsonResult.err().code(JsonResult.NOT_LOGIN).toString());
        }
        //zuul过滤器返回的数据设计为当前扩大应用，
        //目前该返回值没有被应用
        return null;
    }

    //过滤器类型
    @Override
    public String filterType() {
        return FilterConstants.PRE_TYPE;
    }

    //过滤器顺序号
    @Override
    public int filterOrder() {
        //该过滤器程序要 > 5，能力失去 serviceid
        return FilterConstants.PRE_DECORATION_FILTER_ORDER+1;
    }
}

zuul 集成 ribbon

默认启用了负载平衡，但没有启用重试

启用重试

1. 增加 spring-retry 依赖
2. zuul.retryable=true
3. 有默认重试参数(无需配置重试参数)

zuul + hystrix 降级

创立降级类

• getRoute() 办法中指定利用此降级类的服务id，星号或null值能够通配所有服务

@Slf4j
@Component
public class ItemServiceFallback implements FallbackProvider {
    @Override
    public String getRoute() {
        //当执行item-service失败，
        //利用以后这个降级类
        return "item-service";
        //星号和null都示意所有微服务失败都利用以后降级类
        //"*"; //null;
    }

    //该办法返回封装降级响应的对象
    //ClientHttpResponse中封装降级响应
    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return response();
    }

    private ClientHttpResponse response() {
        return new ClientHttpResponse() {
            //上面三个办法都是协定号
            @Override
            public HttpStatus getStatusCode() throws IOException {
                return HttpStatus.OK;
            }
            @Override
            public int getRawStatusCode() throws IOException {
                return HttpStatus.OK.value();
            }
            @Override
            public String getStatusText() throws IOException {
                return HttpStatus.OK.getReasonPhrase();
            }

            @Override
            public void close() {
            }

            @Override
            public InputStream getBody() throws IOException {
                log.info("fallback body");
                String s = JsonResult.err().msg("后盾服务谬误").toString();
                return new ByteArrayInputStream(s.getBytes("UTF-8"));
            }

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