Zookeeper: 数据发布订阅

Zookeeper几大典型应用场景

1.数据发布订阅

2.负载均衡

3.命令服务

4.分布式协调/通知

5.Master选举

6.分布式锁

7.分布式队列

我想每个应用场景均用实例来做一遍加深自己的影响。

本次就写实例：数据发布订阅 .

需求:将一个jdbc的配置放在zookeeper集群下，通过发布订阅，来动态获取jdbc配置。

JDBC配置类

** * jdbc 配置的信息 */public class JdbcConfig {    private String ip;    private int port;    private String username;    private String password;    private int maxConnect;    public String getIp() {        return ip;    }    public void setIp(String ip) {        this.ip = ip;    }    public int getPort() {        return port;    }    public void setPort(int port) {        this.port = port;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public int getMaxConnect() {        return maxConnect;    }    public void setMaxConnect(int maxConnect) {        this.maxConnect = maxConnect;    }    @Override    public String toString() {        return "JdbcConfig{" +                "ip='" + ip + '\'' +                ", port=" + port +                ", username='" + username + '\'' +                ", password='" + password + '\'' +                ", maxConnect=" + maxConnect +                '}';    }

序列化类.

public class MyZkSerializer implements ZkSerializer{    public byte[] serialize(Object data) throws ZkMarshallingError {        try {            return String.valueOf(data).getBytes("UTF-8");        } catch (UnsupportedEncodingException e) {            e.printStackTrace();        }        return null;    }    public Object deserialize(byte[] bytes) throws ZkMarshallingError {        try {            return new String(bytes, "UTF-8");        } catch (UnsupportedEncodingException e) {            e.printStackTrace();        }        return null;    }

发布订阅类.

public class ZkSubScribe {    /**     * 节点名称,配置jdbc     */    private final String JDBC_CONFIG = "/jdbc_config" ;    private final int CONNECT_TIMEOUT = 3000;    private final int SESSION_TIMEOUT = 3000;    private final String SERVERS = "172.16.168.200:2181,172.16.168.200:2182,172.16.168.200:2183";    ZkClient zk;    @Before    public void init(){        zk =  new ZkClient(SERVERS,SESSION_TIMEOUT,CONNECT_TIMEOUT,new MyZkSerializer());        //判断节点是否存在 不存在就创建        boolean isExist = zk.exists(JDBC_CONFIG);        if(!isExist){            JdbcConfig  config = new JdbcConfig();            config.setIp("172.16.168.201");            config.setPort(3306);            config.setPassword("admin");            config.setPassword("admin");            config.setMaxConnect(100);            zk.createPersistent(JDBC_CONFIG,config);        }    }    @Test    public void subscribe(){        System.out.println(zk.readData(JDBC_CONFIG));        zk.subscribeDataChanges(JDBC_CONFIG, new IZkDataListener() {            public void handleDataChange(String dataPath, Object data) throws Exception {                System.out.println("the date change");                System.out.println("the path is "+dataPath);                System.out.println("the new data is "+data);                //这里可以进行后续的jdbc配置管理操作            }            public void handleDataDeleted(String dataPath) throws Exception {            }        });        try {            System.in.read();        } catch (IOException e) {            e.printStackTrace();        }    }    @Test    public void changeData(){        System.out.println("prepare to change data....");        JdbcConfig newConfig = new JdbcConfig();        newConfig.setIp("172.16.168.200");        newConfig.setPort(3306);        newConfig.setUsername("root");        newConfig.setPassword("root");        newConfig.setMaxConnect(100);        zk.writeData(JDBC_CONFIG,newConfig);    }

效果

集中配置管理就是通过Zookeeper的发布订阅功能发来处理。当我们zookeeper管理的节点信息发生改变后，发送给订阅者。