从零搭建一个SpringCloud项目之Zuul(四)

整合Zuul

为什么要使用Zuul？

• 易于监控
• 易于认证
• 减少客户端与各个微服务之间的交互次数

1. 引入依赖

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

1. 配置文件
   
   可不配置，具体配置参数见下文
2. 开启注解

启动类上加@EnableZuulProxy

备注：不配置任何配置文件时，启动zuul服务，zuul可以通过服务名去访问到其他服务。

例：http://localhost:8000/study-trade/trade/testTrade/2

二、配置详解

1. 路径映射

#关闭通过微服务名称访问
zuul.ignored-services=*

#指定微服务名称和路径的映射
#zuul.routes.study-trade=/strade/**

#指定微服务名称和路径的映射,是否剥离前缀
zuul.routes.study-trade.service-id=study-trade
zuul.routes.study-trade.path=/orderservice/**
zuul.routes.study-trade.strip-prefix=true

#指定ip映射，而不用负载均衡
#zuul.routes.study-trade.url=http://localhost:8005/
#zuul.routes.study-trade.path=/st/**

#为我们目标下游服务器设置统一的请求前缀
# 本来是http://localhost:8000/strade/trade/testTrade/2 的配置了就需要http://localhost:8000/study-springcloud/strade/trade/testTrade/2才能访问
#zuul.prefix=/study-springcloud
#是否剥离请求前缀
#zuul.strip-prefix=true

#屏蔽敏感的路径
zuul.ignored-patterns=/**/admin/**

#过滤敏感头信息，不加这行，cookie,setcookie,authrotion三个同步信息不能传递的，等号后不用写值
zuul.routes.study-trade.sensitive-headers=

#禁用Zuul的过滤器  simpleClassname代表类名
#zuul.simpleClassname.pre|router|post|error=true

1. 降级回退

• 宕机回退
• 超时回退（ribbon.ConnectionTimeout=4000
  
  ribbon.ReadTimeout=4000）

代码实现：

/**
 * @description: Zull的降级回退
 * @author: mmc
 * @create: 2020-04-12 22:39
 **/
@Component
public class ZuulFallBack implements FallbackProvider {

    @Override
    public String getRoute() {
        //可以填微服务实例名称或*
        return "*";
    }

    @Override
    public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
        return new ClientHttpResponse() {
            @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 {
                return new ByteArrayInputStream("后端服务异常".getBytes());
            }

            @Override
            public HttpHeaders getHeaders() {
                HttpHeaders httpHeaders=new HttpHeaders();
                httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);
                return httpHeaders;
            }
        };
    }
}

1. 过滤器

@Component
public class ThrowExeceptionFilter extends ZuulFilter {
    @Override
    public String filterType() {
        return "pre";
    }

    @Override
    public int filterOrder() {
        return 0;
    }

    @Override
    public boolean shouldFilter() {
        return true;
    }

    @Override
    public Object run() throws ZuulException {
       return null;
    }
}

1. 统一异常处理

• 4.1 禁用系统异常

  zuul.SendErrorFilter.error.disable=true

• 4.2 自定义异常处理类

@Component
public class ErrorFilter extends SendErrorFilter {

    @Override
    public Object run() {
       try{
           RequestContext ctx = RequestContext.getCurrentContext();
           HttpServletRequest request = ctx.getRequest();
           HttpServletResponse response = ctx.getResponse();
           ExceptionHolder exception = findZuulException(ctx.getThrowable());
           response.setContentType("application/json;charset=utf-8");
           response.setCharacterEncoding("UTF-8");

           Map<String,Object> errorMap=new HashMap<>();
           errorMap.put("code","-1");
           errorMap.put("errMsg",exception.getThrowable().getCause().getMessage());
           response.getWriter().write(JSON.toJSONString(errorMap));
       }catch (Exception e){
           try {
               ReflectionUtils.rethrowException(e);
           } catch (Exception e1) {
               e1.printStackTrace();
           }
       }
       return null;
    }
}