netflix zuul

introduction

zuul用來提供動(dòng)態(tài)路由、監(jiān)控、授權(quán)、安全、調(diào)度等等的邊緣服務(wù)(edge service)

ZuulFilter

ZuulFilter是Zuul中核心組件，通過繼承該抽象類，覆寫幾個(gè)關(guān)鍵方法達(dá)到自定義調(diào)度請(qǐng)求的作用,這里filter不是Java web中的filter，不要混淆.

new ZuulFilter() {                @Override                public int filterOrder() {                    return 0;                }                @Override                public String filterType() {                    return null;                }                @Override                public boolean shouldFilter() {                    return false;                }                @Override                public Object run() {                    return null;                }            }
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filterOrder:filter執(zhí)行順序，通過數(shù)字指定
shouldFilter:filter是否需要執(zhí)行 true執(zhí)行 false 不執(zhí)行
run : filter具體邏輯
filterType :filter類型,分為以下幾種

pre:請(qǐng)求執(zhí)行之前filter
route: 處理請(qǐng)求，進(jìn)行路由
post: 請(qǐng)求處理完成后執(zhí)行的filter
error:出現(xiàn)錯(cuò)誤時(shí)執(zhí)行的filter

quick start

直接給出一個(gè)簡(jiǎn)單demo，通過demo代碼再具體解析

package com.lkl.springcloud.zuul;import com.netflix.zuul.ZuulFilter;import com.netflix.zuul.context.ContextLifecycleFilter;import com.netflix.zuul.context.RequestContext;import com.netflix.zuul.filters.FilterRegistry;import com.netflix.zuul.http.ZuulServlet;import com.netflix.zuul.monitoring.MonitoringHelper;import org.springframework.boot.CommandLineRunner;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;import org.springframework.boot.context.embedded.FilterRegistrationBean;import org.springframework.boot.context.embedded.ServletRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.stereotype.Component;import java.io.IOException;/** * Created by liaokailin on 16/5/24. */@SpringBootApplicationpublic class Application {    public static void main(String[] args) {        new SpringApplicationBuilder(Application.class).web(true).run(args);    }    @Component    public static class MyCommandLineRunner implements CommandLineRunner {        @Override        public void run(String... args) throws Exception {            MonitoringHelper.initMocks();            initJavaFilters();        }        private void initJavaFilters() {            final FilterRegistry r = FilterRegistry.instance();            r.put("javaPreFilter", new ZuulFilter() {                @Override                public int filterOrder() {                    return 50000;                }                @Override                public String filterType() {                    return "pre";                }                @Override                public boolean shouldFilter() {                    return true;                }                @Override                public Object run() {                    System.out.println("running javaPreFilter");                    RequestContext.getCurrentContext().set("name", "liaokailin");                    return null;                }            });            r.put("javaRoutingFilter", new ZuulFilter() {                @Override                public int filterOrder() {                    return 50000;                }                @Override                public String filterType() {                    return "route";                }                @Override                public boolean shouldFilter() {                    return true;                }                @Override                public Object run() {                    System.out.println("running javaRoutingFilter");                    try {                        RequestContext.getCurrentContext().getResponse().sendRedirect("http://blog.csdn.net/liaokailin/");                    } catch (IOException e) {                        e.printStackTrace();                    }                    return null;                }            });            r.put("javaPostFilter", new ZuulFilter() {                @Override                public int filterOrder() {                    return 50000;                }                @Override                public String filterType() {                    return "post";                }                @Override                public boolean shouldFilter() {                    return true;                }                @Override                public Object run() {                    System.out.println("running javaPostFilter");                    System.out.println(RequestContext.getCurrentContext().get("name").toString());                    return null;                }            });        }    }    @Bean    public ServletRegistrationBean zuulServlet() {        ServletRegistrationBean servlet = new ServletRegistrationBean(new ZuulServlet());        servlet.addUrlMappings("/test");        return servlet;    }    @Bean    public FilterRegistrationBean contextLifecycleFilter() {        FilterRegistrationBean filter = new FilterRegistrationBean(new ContextLifecycleFilter());        filter.addUrlPatterns("/*");        return filter;    }}
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servlet注冊(cè)

通過ServletRegistrationBean構(gòu)造ZuulServlet，該Servlet用以進(jìn)行filter執(zhí)行調(diào)度以及監(jiān)控等等操作
訪問 http://localhost:8080/test 進(jìn)入該servlet

filter注冊(cè)

通過FilterRegistrationBean進(jìn)行filter注冊(cè)，ContextLifecycleFilter的核心功能是為了清除RequestContext；
請(qǐng)求上下文通過ThreadLocal存儲(chǔ)，因此需要在請(qǐng)求完成后刪除該對(duì)象。

CommandLineRunner

CommandLineRunner接口很簡(jiǎn)單，知道spring boot的知道其功能，在工程啟動(dòng)后會(huì)執(zhí)行對(duì)應(yīng)run方法:

MonitoringHelper.initMocks(); 啟動(dòng)監(jiān)控，這個(gè)再后續(xù)文章中具體再說
initJavaFilters()方法中注冊(cè)三種類型filter

RequestContext

RequestContext 在zuul有很重作用，在不同組件傳遞數(shù)據(jù)都是通過它來實(shí)現(xiàn)的

啟動(dòng)工程后訪問 http://localhost:8080/test 可以看到后臺(tái)答應(yīng)消息，頁(yè)面也會(huì)定位到我的博客首頁(yè)。

zuul執(zhí)行流程

借用官網(wǎng)的一張圖片

通過圖片可以清晰看出執(zhí)行過程，在微服務(wù)中后端各種引用，利用zuul進(jìn)行合理調(diào)用還是很有必要的，例如 負(fù)載、限流、監(jiān)控、安全等等功能。

zuul with groovy

為了動(dòng)態(tài)修改filter，zuul利用groovy,它是基于jvm的語言，語法簡(jiǎn)單而且和Java很類似，可以簡(jiǎn)單的理解為在java語法上進(jìn)行拓展，但groovy是可以動(dòng)態(tài)加載的，應(yīng)用發(fā)布到線上后可以在不重啟情況下對(duì)業(yè)務(wù)邏輯進(jìn)行修改。

為了簡(jiǎn)單起見，下面創(chuàng)建一個(gè)groovy filter

import com.netflix.zuul.ZuulFilterimport com.netflix.zuul.context.RequestContextimport javax.servlet.http.HttpServletRequestclass PreRequest extends ZuulFilter{    @Override    String filterType() {        return "pre"    }    @Override    int filterOrder() {        return 1000    }    @Override    boolean shouldFilter() {        return true    }    @Override    Object run() {        HttpServletRequest req = RequestContext.currentContext.request as HttpServletRequest        Iterator headerIt = req.getHeaderNames().iterator()        while (headerIt.hasNext()) {            String name = (String) headerIt.next()            String value = req.getHeader(name)            println("header: " + name + ":" + value)        }        return null    }}
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創(chuàng)建一個(gè)pre類型的filter，在run方法中獲取HttpServletRequest 然后答應(yīng)header信息

在代碼中加入groovy編譯器，間隔10秒掃描一次groovy文件，其代碼如下：

 <dependency>            <groupId>org.codehaus.groovy</groupId>            <artifactId>groovy-all</artifactId>            <version>2.4.4</version>        </dependency>
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 FilterLoader.getInstance().setCompiler(new GroovyCompiler());            try {                FilterFileManager.setFilenameFilter(new GroovyFileFilter());                FilterFileManager.init(10,"/Users/liaokailin/code/ieda/springcloud/myzuul/src/main/java/com/lkl/springcloud/zuul/filters/groovy/pre");            } catch (Exception e) {                throw new RuntimeException(e);            }
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這里groovy文件通過絕對(duì)路徑指定，如果是實(shí)際開發(fā)中，可以通過db去存儲(chǔ)groovy文件。

啟動(dòng)應(yīng)用后再訪問該工程，可以發(fā)現(xiàn)header信息全部答應(yīng)出來。

ok ~ it’s work ! more about is here
轉(zhuǎn)載請(qǐng)注明
http://blog.csdn.net/liaokailin/article/details/51525908

歡迎關(guān)注，您的肯定是對(duì)我最大的支持