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很多使用Zookeeper的情景是需要我们嵌入Zookeeper作为自己的分布式应用系统的一部分来提供分布式服务，此时我们需要通过程序的方式来启动Zookeeper。此时可以通过Zookeeper API的ZooKeeperServerMain类来启动Zookeeper服务。

下面是一个集群模式下启动Zookeeper服务的例子

这里假定我们运行Zookeeper集群的三台机器名分别为fanbinx1,fanbinx2,fanbinx3

首先是zoo.cfg配置文件

[plain] view plain copy print?
tickTime=2000  
dataDir=/tmp/zookeeper/data  
clientPort=2181  
initLimit=10  
syncLimit=5  
server.1=fanbinx1:2888:3888  
server.2=fanbinx2:2888:3888  
server.3=fanbinx3:2888:3888  
启动Zookeeper集群服务的类，如下 
* 这个类同时使用同一个zoo.cfg配置文件来启动Zookeeper服务。
* 在每台机器上启动Zookeeper服务的时候判断当前机器是不是定义在zoo.cfg文件里，如果是获取其中的ID号，然后生成myid文件并将ID写入其中。
* 最后启动Zookeeper服务。

[java] view plain copy print?
package my.zookeeperstudy.server;  

import org.apache.commons.io.FileUtils;  
import org.apache.zookeeper.server.ServerConfig;  
import org.apache.zookeeper.server.ZooKeeperServerMain;  
import org.apache.zookeeper.server.quorum.QuorumPeerConfig;  

import java.io.File;  
import java.io.InputStream;  
import java.net.InetAddress;  
import java.util.Properties;  
import java.util.regex.Matcher;  
import java.util.regex.Pattern;  

public class ClusteredZKServer {  

    public static void main(String[] args) throws Exception {  
        InputStream is = ClusteredZKServer.class.getResourceAsStream("/my/zookeeperstudy/server/zoo.cfg");  
        Properties props = new Properties();  
        try {  
            props.load(is);  
        } finally {  
            is.close();  
        }  

        for (String key : props.stringPropertyNames()) {  
            Pattern pKey = Pattern.compile("^server\\.(\\d)");  
            Pattern pValue = Pattern.compile("([\\w|.]*):\\d*:\\d*");  
            Matcher mKey = pKey.matcher(key);  
            Matcher mValue = pValue.matcher(props.getProperty(key));  
            if (mKey.find() && mValue.find()) {  
                String id = mKey.group(1);  
                String host = mValue.group(1);  
                String thisHostName = InetAddress.getLocalHost().getHostName();  
                String thisHostAddress = InetAddress.getLocalHost().getHostAddress();  
                if (host.equals(thisHostName) || host.equals(thisHostAddress)) {  
                    //System.out.println(new File(props.getProperty("dataDir"), "myid").getAbsolutePath());  
                    FileUtils.write(new File(props.getProperty("dataDir"), "myid"), id);  
                    QuorumPeerConfig quorumConfig = new QuorumPeerConfig();  
                    quorumConfig.parseProperties(props);  

                    final ZooKeeperServerMain zkServer = new ZooKeeperServerMain();  
                    final ServerConfig config = new ServerConfig();  
                    config.readFrom(quorumConfig);  
                    zkServer.runFromConfig(config);  
                }  
            }  
        }  
    }  
}  
客户端测试代码如下，这里可以修改hostname为集群中的任意一台机器

[java] view plain copy print?
package my.zookeeperstudy.server;  

import org.apache.zookeeper.*;  

import java.util.List;  

public class Client {  
    public static void main(String[] args) throws Exception {  
        ZooKeeper zk = new ZooKeeper("fanbinx1:2181,fanbinx2:2181,fanbinx3:2181", 10000,  
                new Watcher() {  
                    public void process(WatchedEvent event) {  
                        System.out.println("event: " + event.getType());  
                    }  
                });  

        System.out.println(zk.getState());  

        zk.create("/myApps", "myAppsData".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);  
        zk.create("/myApps/App1", "App1Data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);  
        zk.create("/myApps/App2", "App2Data".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);  
        zk.create("/myApps/App3", "".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);  
        zk.setData("/myApps/App3","App3Data".getBytes(), -1);  

        System.out.println(zk.exists("/myApps", true));  
        System.out.println(new String(zk.getData("/myApps", true, null)));  

        List

  children = zk.getChildren("/myApps", true);  
        for (String child : children) {  
            System.out.println(new String(zk.getData("/myApps/" + child, true, null)));  
            zk.delete("/myApps/" + child,-1);  
        }  

        zk.delete("/myApps",-1);  

        zk.close();  
    }  
}  

测试
* 在集群中的各个机器上分别运行ClusteredZKServer类来启动Zookeeper服务。
* 然后在任意一台机器上运行Client类来连接Zookeeper并操作数据。