Zookeeper三个监听案例

一、监听某一节点内容

/**
 * @author: princesshug
 * @date: 2019/2/25, 14:28
 * @blog: https://www.cnblogs.com/hellobigtable/
 * 监听一个节点内容的变化
 */
public class watchzonedemo {
    zookeeper zkcli = null;

    public static void main(string[] args) throws ioexception, interruptedexception {
        watchzonedemo wz = new watchzonedemo();
        wz.getconnection();
        thread.sleep(long.max_value);
    }

    private void getconnection() throws ioexception {
        zkcli = new zookeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new watcher() {
            public void process(watchedevent watchedevent) {
                try {
                    byte[] data = zkcli.getdata("/wyh", true, null);
                    system.out.println("监听类型为：" + watchedevent.gettype());
                    system.out.println("监听路径为：" + watchedevent.getpath());
                    system.out.println("数据被修改为：" + new string(data));
                    system.out.println("=======================================");
                } catch (keeperexception e) {
                    e.printstacktrace();
                } catch (interruptedexception e) {
                    e.printstacktrace();
                }
            }
        });
    }
}

二、监听某节点目录的变化

/**
 * @author: princesshug
 * @date: 2019/2/25, 14:57
 * @blog: https://www.cnblogs.com/hellobigtable/
 * 监听一个节点的子节点的变化
 */
public class watchchildrendemo {
    zookeeper zkcli = null;

    public static void main(string[] args) throws ioexception, interruptedexception {
        watchchildrendemo wc = new watchchildrendemo();
        wc.getconnction();
        thread.sleep(long.max_value);
    }

    private void getconnction() throws ioexception {
        zkcli = new zookeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new watcher() {
            public void process(watchedevent watchedevent) {
                arraylist<string> nodes = new arraylist<string>();
                try {
                    list<string> children = zkcli.getchildren("/", true);
                    for (string c:children){
                        nodes.add(c);
                    }
                    system.out.println(nodes);
                } catch (keeperexception e) {
                    e.printstacktrace();
                } catch (interruptedexception e) {
                    e.printstacktrace();
                }
            }
        });
    }
}

三、zookeeper当太上下线的感知系统

　　1.需求：某分布式系统中，主节点有多台，可以进行动态上下限，当有任何一台机器发生了动态的上下线， 任何一台客户端都能感知得到

　　2.思路：

　　　　(1)创建客户端与服务端

　　　　(2)启动client端 并监听

　　　　(3)启动server端 并注册

　　　　(4)当server端发生上下线

　　　　(5)client端都能感知的到

　　3.代码

public class zkserver {
    zookeeper zk = null;
    private string parentnode = "/servers";

    public static void main(string[] args) throws ioexception, keeperexception, interruptedexception {
        string childnode = "hd1-1";
        zkserver zkserver = new zkserver();
        //获取连接
        zkserver.getconnection();
        //注册信息
        zkserver.regist(childnode);
        //业务逻辑，提示上线
        zkserver.build(childnode);

    }

    private void build(string hostname) throws interruptedexception {
        system.out.println(hostname + "上线了！！");
        thread.sleep(long.max_value);
    }

    private void regist(string hostname) throws keeperexception, interruptedexception {
        string path = zk.create(parentnode + "/server", hostname.getbytes(), zoodefs.ids.open_acl_unsafe, createmode.ephemeral_sequential);
        system.out.println(path);
    }

    private void getconnection() throws ioexception {
        zk = new zookeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new watcher() {
            public void process(watchedevent watchedevent) {

            }
        });
    }
}

public class zkclient {
    zookeeper zk = null;
    public static void main(string[] args) throws ioexception, keeperexception, interruptedexception {
        zkclient zkclient = new zkclient();
        zkclient.getconnection();
        zkclient.watching();
    }

    private void watching() throws interruptedexception {
        thread.sleep(long.max_value);
    }

    private void getconnection() throws ioexception {
        zk = new zookeeper("192.168.126.128:2181,192.168.126.129:2181,192.168.126.130:2181", 3000, new watcher() {
            public void process(watchedevent watchedevent) {
                try {
                    list<string> children = zk.getchildren("/servers", true);
                    arraylist<string> node = new arraylist<string>();
                    for (string c:children){
                        byte[] data = zk.getdata("/servers/" + c, true, null);
                        node.add(new string(data));
                    }
                    system.out.println(node);
                } catch (keeperexception e) {
                    e.printstacktrace();
                } catch (interruptedexception e) {
                    e.printstacktrace();
                }
            }
        });
    }
}