0604-Zuul构建API Gateway-Zuul的回退

一、概述

　　参看地址：https://cloud.spring.io/spring-cloud-static/Edgware.SR3/single/spring-cloud.html#hystrix-fallbacks-for-routes

　　Zuul本事是基于Hystrix和Ribbon等，默认会支持Hystrix的Command等

　　在Zuul给定的路由回路跳闸，可以通过创建一个类型为ZuulFallbackProvider的bean来提供回退响应。在此bean中，您需要指定回退的路由ID，并提供ClientHttpResponse作为回退。这是一个非常简单的ZuulFallbackProvider实现。

二、提供Hystrix路由回退

　　当Zuul中给定路由的电路被触发时，您可以通过创建一个类型为ZuulFallbackProvider的bean来提供回退响应。在此bean中，您需要指定回退的路由ID，并提供ClientHttpResponse作为回退。这是一个非常简单的ZuulFallbackProvider实现。

class MyFallbackProvider implements ZuulFallbackProvider {

    @Override

    public String getRoute() {

        return "customers";

    }

    @Override

    public ClientHttpResponse fallbackResponse() {

        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

            public InputStream getBody() throws IOException {

                return new ByteArrayInputStream("fallback".getBytes());

            }

            @Override

            public HttpHeaders getHeaders() {

                HttpHeaders headers = new HttpHeaders();

                headers.setContentType(MediaType.APPLICATION_JSON);

                return headers;

            }

        };

    }

}

路由配置

zuul:

  routes:

    customers: /customers/**

如果您希望为所有路由提供默认回退，则可以创建类型为ZuulFallbackProvider的bean，并让getRoute方法返回*或null

class MyFallbackProvider implements ZuulFallbackProvider {

    @Override

    public String getRoute() {

        return "*";

    }

    @Override

    public ClientHttpResponse fallbackResponse() {

        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

            public InputStream getBody() throws IOException {

                return new ByteArrayInputStream("fallback".getBytes());

            }

            @Override

            public HttpHeaders getHeaders() {

                HttpHeaders headers = new HttpHeaders();

                headers.setContentType(MediaType.APPLICATION_JSON);

                return headers;

            }

        };

    }

}

如果您想选择基于故障原因的响应，请使用FallbackProvider，它将替换未来版本中的ZuulFallbackProvder。

class MyFallbackProvider implements FallbackProvider {

    @Override

    public String getRoute() {

        return "*";

    }

    @Override

    public ClientHttpResponse fallbackResponse(final Throwable cause) {

        if (cause instanceof HystrixTimeoutException) {

            return response(HttpStatus.GATEWAY_TIMEOUT);

        } else {

            return fallbackResponse();

        }

    }

    @Override

    public ClientHttpResponse fallbackResponse() {

        return response(HttpStatus.INTERNAL_SERVER_ERROR);

    }

    private ClientHttpResponse response(final HttpStatus status) {

        return new ClientHttpResponse() {

            @Override

            public HttpStatus getStatusCode() throws IOException {

                return status;

            }

            @Override

            public int getRawStatusCode() throws IOException {

                return status.value();

            }

            @Override

            public String getStatusText() throws IOException {

                return status.getReasonPhrase();

            }

            @Override

            public void close() {

            }

            @Override

            public InputStream getBody() throws IOException {

                return new ByteArrayInputStream("fallback".getBytes());

            }

            @Override

            public HttpHeaders getHeaders() {

                HttpHeaders headers = new HttpHeaders();

                headers.setContentType(MediaType.APPLICATION_JSON);

                return headers;

            }

        };

    }

}

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