一起来学SpringCloud之

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在实际生产中，我们需要高可用的集群方案，本章就是基于SpringBoot1.5.4 Cloud（Dalston.SR2）的高可用Eureka Cluster，以及生产中需要注意的事项…

- Eureka Cluster

本教程用1个项目（battcn-cloud-discovery），多环境方式演示

- pom.xml

<dependencies>    <dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-eureka-server</artifactId>    </dependency>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-test</artifactId>        <scope>test</scope>    </dependency></dependencies>

- Application.java

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

- application.yml

server:  port: 8761spring:  profiles:    active: peer2  #官方写的就是 8761---spring:  profiles: peer1  application:    name: Eureka-Server-1eureka:  instance:    hostname: peer1    #配置主机名  client:    register-with-eureka: false    #配置服务注册中心是否以自己为客户端进行注册(配置false)    fetch-registry: false    #是否取得注册信息(配置false)    service-url:      defaultZone: http://peer2:7002/eureka/      #defaultZone 一定要按照标准写法，因为service-url的数据类型是Map 这算是个小坑需要注意server:  port: 7001---spring:  profiles: peer2  application:    name: Eureka-Server-1eureka:  instance:    hostname: peer2    #配置主机名  client:    register-with-eureka: false    #配置服务注册中心是否以自己为客户端进行注册(配置false)    fetch-registry: false    #是否取得注册信息(配置false)    service-url:      defaultZone: http://peer1:7001/eureka/server:  port: 7002      #defaultZone 一定要按照标准写法，因为service-url的数据类型是Map 这算是个小坑需要注意

- 启动集群

命令：mvn clean package （先打成jar包）

peer1：java -jar battcn-cloud-discovery.jar --spring.profiles.active=peer1peer2：java -jar battcn-cloud-discovery.jar --spring.profiles.active=peer2

1.点击蓝色加号
2.点击Spring Boot
3.填写 Name：peer1 Program arguments：–spring.profiles.active=peer1（启动2个操作2次，记得改名字和激活环境，Eclipse太简单了application.yml 直接修改内容启动就行了）

启动多个

启动成功分别访问

    http://peer1:7001

peer1

    http://peer2:7002

peer2

如出现上图所示，代表我们集群启动成功

- 高可用测试

1.创建battcn-cloud-h1 和 battcn-cloud-h2 2个项目，基本大同小异

就这2个包够了，跟 h1 代码唯一的区别就是 h2 做调用 h1写好接口就行了

- pom.xml

<dependencies>    <dependency>        <groupId>org.springframework.cloud</groupId>        <artifactId>spring-cloud-starter-eureka</artifactId>    </dependency>    <dependency>        <groupId>org.springframework.boot</groupId>        <artifactId>spring-boot-starter-test</artifactId>        <scope>test</scope>    </dependency></dependencies>

- application.yml

server:   port: 7012spring:  application:    name: battcn-cloud-h2eureka:  instance:    hostname: localhost #配置主机名  client:    service-url:      defaultZone: http://peer1:7001/eureka/,http://peer2:7002/eureka/   #配置Eureka Server

- H2Application.java

@SpringBootApplication@EnableDiscoveryClient@RestControllerpublic class H2Application {    static Logger LOGGER = LoggerFactory.getLogger(H2Application.class);    @Bean    @LoadBalanced    RestTemplate restTemplate() {        return new RestTemplate();    }    @RequestMapping("/h2")    public String home(@RequestParam String email) {        // 改写法之前有说过是VIP模式        return restTemplate().getForObject("http://battcn-cloud-h1/h1?email=" + email, String.class);    }    public static void main(String[] args) {        SpringApplication.run(H2Application.class, args);    }}

- 测试

分别启动 battcn-cloud-h1 和 battcn-cloud-h2

服务注册

访问：http://localhost:7012/h2?email=1837307557@qq.com

浏览器：My Name's :battcn-cloud-h1 Email:1837307557@qq.com 代表请求成功，然后我们断掉 peer1 或者 peer2 继续请求依旧可用，只是日志会抛异常，通过日志我们可以发现peer2 time out 因为它被杀掉了，但是这并不影响我们服务调用(高可用)，只要在启动peer2 错误就不会在出现，在生产中如果集群都挂了直接运维下岗就是了（如果peer1 peer2同时挂掉，在启动服务会自动注册上去.）

2017-07-31 23:01:03.314 ERROR 14792 --- [-target_peer2-8] c.n.e.cluster.ReplicationTaskProcessor   : Network level connection to peer peer2; retrying after delaycom.sun.jersey.api.client.ClientHandlerException: org.apache.http.conn.ConnectTimeoutException: Connect to peer2:7002 timed out    at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:187) ~[jersey-apache-client4-1.19.1.jar:1.19.1]    at com.netflix.eureka.cluster.DynamicGZIPContentEncodingFilter.handle(DynamicGZIPContentEncodingFilter.java:48) ~[eureka-core-1.6.2.jar:1.6.2]    at com.netflix.discovery.EurekaIdentityHeaderFilter.handle(EurekaIdentityHeaderFilter.java:27) ~[eureka-client-1.6.2.jar:1.6.2]    at com.sun.jersey.api.client.Client.handle(Client.java:652) ~[jersey-client-1.19.1.jar:1.19.1]    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:682) ~[jersey-client-1.19.1.jar:1.19.1]    at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74) ~[jersey-client-1.19.1.jar:1.19.1]    at com.sun.jersey.api.client.WebResource$Builder.post(WebResource.java:570) ~[jersey-client-1.19.1.jar:1.19.1]    at com.netflix.eureka.transport.JerseyReplicationClient.submitBatchUpdates(JerseyReplicationClient.java:116) ~[eureka-core-1.6.2.jar:1.6.2]    at com.netflix.eureka.cluster.ReplicationTaskProcessor.process(ReplicationTaskProcessor.java:71) ~[eureka-core-1.6.2.jar:1.6.2]    at com.netflix.eureka.util.batcher.TaskExecutors$BatchWorkerRunnable.run(TaskExecutors.java:187) [eureka-core-1.6.2.jar:1.6.2]    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_60]Caused by: org.apache.http.conn.ConnectTimeoutException: Connect to peer2:7002 timed out    at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:123) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:144) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:134) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:610) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:445) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:118) ~[httpclient-4.5.3.jar:4.5.3]    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.3.jar:4.5.3]    at com.sun.jersey.client.apache4.ApacheHttpClient4Handler.handle(ApacheHttpClient4Handler.java:173) ~[jersey-apache-client4-1.19.1.jar:1.19.1]    ... 10 common frames omitted

- 注意事项

EurekaClientConfigBean.java 默认构造方法，如果serviceUrl.defaultZone = null 那么就注册到 http://localhost:8761/eureka/ 中去（日志会输出改地址，起初我是看的一脸懵逼），所以其他的Key都可以以杠(-) 或者全大写方式，该处不行，因为人家源码是Map不是对象

public EurekaClientConfigBean() {    this.serviceUrl.put("defaultZone", "http://localhost:8761/eureka/");    this.gZipContent = true;    this.useDnsForFetchingServiceUrls = false;    this.registerWithEureka = true;    this.preferSameZoneEureka = true;    this.availabilityZones = new HashMap();    this.filterOnlyUpInstances = true;    this.fetchRegistry = true;    this.dollarReplacement = "_-";    this.escapeCharReplacement = "__";    this.allowRedirects = false;    this.onDemandUpdateStatusChange = true;    this.clientDataAccept = EurekaAccept.full.name();}public String[] getAvailabilityZones(String region) {    String value = (String)this.availabilityZones.get(region);    if(value == null) {        value = "defaultZone";    }    return value.split(",");}public List<String> getEurekaServerServiceUrls(String myZone) {    String serviceUrls = (String)this.serviceUrl.get(myZone);    if(serviceUrls == null || serviceUrls.isEmpty()) {        serviceUrls = (String)this.serviceUrl.get("defaultZone");    }    if(!StringUtils.isEmpty(serviceUrls)) {        String[] serviceUrlsSplit = StringUtils.commaDelimitedListToStringArray(serviceUrls);        List<String> eurekaServiceUrls = new ArrayList(serviceUrlsSplit.length);        String[] var5 = serviceUrlsSplit;        int var6 = serviceUrlsSplit.length;        for(int var7 = 0; var7 < var6; ++var7) {            String eurekaServiceUrl = var5[var7];            if(!this.endsWithSlash(eurekaServiceUrl)) {                eurekaServiceUrl = eurekaServiceUrl + "/";            }            eurekaServiceUrls.add(eurekaServiceUrl);        }        return eurekaServiceUrls;    } else {        return new ArrayList();    }}

- 小谈

其实我是比较倾向于 consul 这种零侵入式的，但是consul 在做高可用比较操蛋，它对外暴露的是 agent 如果你这个 agent挂了，那么后面服务就GG思密达了，cloud service 不允许配置多个agent，个人没找到好的解决方案，有好方案的可以交流…..

- 说点什么

微信公众号：battcn（欢迎调戏）

本章代码（Eureka-Cluster）：https://git.oschina.net/battcn/battcn-cloud/tree/master/battcn-cloud-discovery

本章代码（Client-H1/H2）：https://git.oschina.net/battcn/battcn-cloud/tree/master/battcn-cloud-discovery-cluster-test

如有问题请及时与我联系

个人QQ：1837307557
Spring Cloud中国社区①：415028731
Spring For All 社区⑤：157525002

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