需求
某分布式系统中,主节点可以有多台,可以动态上下线,任意一台客户端都能实时感知到主节点服务器的上下线。
需求分析
具体实现
先在集群上创建/servers节点
create /servers "servers"
一些依赖
pom.xml:
<project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelversion>4.0.0</modelversion> <groupid>com.mcq</groupid> <artifactid>zookeeper1026</artifactid> <version>0.0.1-snapshot</version> <dependencies> <dependency> <groupid>junit</groupid> <artifactid>junit</artifactid> <version>release</version> </dependency> <dependency> <groupid>org.apache.logging.log4j</groupid> <artifactid>log4j-core</artifactid> <version>2.8.2</version> </dependency> <!-- https://mvnrepository.com/artifact/org.apache.zookeeper/zookeeper --> <dependency> <groupid>org.apache.zookeeper</groupid> <artifactid>zookeeper</artifactid> <version>3.4.10</version> </dependency> </dependencies> </project>
在src/main/resources下添加一个file log4j.properties:
log4j.rootlogger=info, stdout log4j.appender.stdout=org.apache.log4j.consoleappender log4j.appender.stdout.layout=org.apache.log4j.patternlayout log4j.appender.stdout.layout.conversionpattern=%d %p [%c] - %m%n log4j.appender.logfile=org.apache.log4j.fileappender log4j.appender.logfile.file=target/spring.log log4j.appender.logfile.layout=org.apache.log4j.patternlayout log4j.appender.logfile.layout.conversionpattern=%d %p [%c] - %m%n
服务器端向 zookeeper 注册代码
package com.mcq.zookeeper1026; import java.io.ioexception; import org.apache.zookeeper.createmode; import org.apache.zookeeper.keeperexception; import org.apache.zookeeper.watchedevent; import org.apache.zookeeper.watcher; import org.apache.zookeeper.zoodefs.ids; import org.apache.zookeeper.zookeeper; public class distributeserver { private string connectstring = "hadoop103:2181,hadoop104:2181,hadoop105:2181"; private int sessiontimeout = 2000; private zookeeper zk = null; private string parentnode = "/servers"; public void getconnect() throws ioexception { zk = new zookeeper(connectstring, sessiontimeout, new watcher() { @override public void process(watchedevent event) { // todo auto-generated method stub } }); } // 注册服务器 public void registserver(string hostname) throws exception { system.out.println(zk); string path = zk.create(parentnode + "/server", hostname.getbytes(), ids.open_acl_unsafe, createmode.ephemeral_sequential); system.out.println(hostname + " is online " + path); } // 业务功能 public void business(string hostname) throws interruptedexception { system.out.println(hostname + " is working ……"); thread.sleep(long.max_value); } public static void main(string[] args) throws exception { // 1.获取zk连接 distributeserver server = new distributeserver(); server.getconnect(); // 2.利用zk连接注册服务器信息 server.registserver(args[0]); // 3.启动业务功能 server.business(args[0]); } }
客户端代码
package com.mcq.zookeeper1026; import java.io.ioexception; import java.util.arraylist; import java.util.list; import org.apache.zookeeper.keeperexception; import org.apache.zookeeper.watchedevent; import org.apache.zookeeper.watcher; import org.apache.zookeeper.zookeeper; public class distributeclient { public static void main(string[] args) throws ioexception, keeperexception, interruptedexception { //1.获取zk连接 distributeclient client=new distributeclient(); client.getconnect(); //2.获取servers的子节点信息,从中获取服务器信息列表 client.getserverlist(); //3.业务进程启动 client.business(); } private void business() throws interruptedexception { // todo auto-generated method stub system.out.println("client is working ……"); thread.sleep(long.max_value); } private string parentnode="/servers"; private void getserverlist() throws keeperexception, interruptedexception { // todo auto-generated method stub //1.获取服务器子节点信息,并且对父节点进行监听 list<string> children = zk.getchildren(parentnode,true); //2.存储服务器信息列表 arraylist<string> servers=new arraylist<>(); //3.遍历所有节点,获取节点中的主机名称信息 for(string child:children) { byte[] data=zk.getdata(parentnode+"/"+child,false,null); servers.add(new string(data)); } //4.打印服务器列表信息 system.out.println(servers); } private zookeeper zk=null; private string connectstring="hadoop103:2181,hadoop104:2181,hadoop105:2181"; private int sessiontimeout=2000; private void getconnect() throws ioexception { // todo auto-generated method stub //创建到zk的客户端连接 zk=new zookeeper(connectstring,sessiontimeout,new watcher() { @override public void process(watchedevent event) { // todo auto-generated method stub try { getserverlist(); }catch(exception e) { e.printstacktrace(); } } }); } }
运行程序
先运行客户端
在xshell上登录客户端(bin/zkcli.sh),进行一些操作,可以看到eclipse的控制台会实时输出有哪些节点。
然后运行服务器端,记得先在run configuration里设置一下参数,比如设成hadoop103,那么运行后,客户端的控制台会实时显示当前的节点。
点上面那个红框可以切换控制台。