微服务Zuul网关实现服务降级

spring boot版本：2.1.10.RELEASE

1、项目搭建

所需依赖及项目的搭建请参考上一篇博客 微服务中网关的作用及搭建

2、添加fallback的bean

在spring boot 2.0之前实现的是 ZuulFallbackProvider接口，但是在spring boot 2.0之后实现的是 FallbackProvider 接口。

package com.ebook.zuul.fallback;

import org.springframework.cloud.netflix.zuul.filters.route.FallbackProvider;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.client.ClientHttpResponse;
import org.springframework.stereotype.Component;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;

/**
 * @author:JZ
 * @date:2020/1/28
 */

@Component
public class ProductFallbackProvider implements FallbackProvider {

    /**
     * 返回的是服务的路由，即服务的名称，
     * 代表为哪个服务提供fallback
     * @return
     */
    @Override
    public String getRoute() {
        return "ebook-product-core";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {

            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders header = new HttpHeaders();
                MediaType mt = new MediaType("application", "json", Charset.forName("UTF-8"));
                header.setContentType(mt);
                return header;
            }

            @Override
            public InputStream getBody() throws IOException {
                String input="商品服务不可用，请联系管理员！";
                return new ByteArrayInputStream(input.getBytes());
            }

            @Override
            public HttpStatus getStatusCode() throws IOException {
                //HttpResponse的fallback的状态码,HttpStatus值
                return HttpStatus.OK;
            }

            @Override
            public int getRawStatusCode() throws IOException {
                //HttpResponse的fallback的状态码,int值
                return this.getStatusCode().value();
            }

            @Override
            public String getStatusText() throws IOException {
                //HttpResponse的fallback的状态码,string
                return this.getStatusCode().getReasonPhrase();
            }

            @Override
            public void close() {

            }
        };
    }
}