zookeeper
环境准备
至少2台zookeeper的集群,启动zkServer.sh start
eclipse环境要可以连接zookeeper的集群
1.zookeeper 增删盖茶
package cn.itcast.bigdata.zk; import java.io.IOException; import java.util.List; 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; import org.apache.zookeeper.data.Stat; import org.junit.Before; import org.junit.Test; public class SimpleZkClient { private static final String connectString = "h42:2181,h43:2181"; private static final int sessionTimeout = 2000; ZooKeeper zkClient = null; @Before public void init() throws Exception { zkClient = new ZooKeeper(connectString, sessionTimeout, new Watcher() { @Override public void process(WatchedEvent event) { // 收到事件通知后的回调函数(应该是我们自己的事件处理逻辑) System.out.println(event.getType() + "---" + event.getPath()); try { zkClient.getChildren("/", true); } catch (Exception e) { } } }); } /** * 数据的增删改查 * * @throws InterruptedException * @throws KeeperException */ // 创建数据节点到zk中 // @Test public void testCreate() throws KeeperException, InterruptedException { // 参数1:要创建的节点的路径 参数2:节点大数据 参数3:节点的权限 参数4:节点的类型 String nodeCreated = zkClient.create("/eclipse", "hellozk".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); //上传的数据可以是任何类型,但都要转成byte[] } //判断znode是否存在 // @Test public void testExist() throws Exception{ Stat stat = zkClient.exists("/eclipse", false); try { System.out.println(stat==null?"not exist":"exist"); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } // 获取子节点 // @Test public void getChildren() throws Exception { List<String> children = zkClient.getChildren("/", true); for (String child : children) { System.out.println(child); } Thread.sleep(Long.MAX_VALUE); } //获取znode的数据 @Test public void getData() throws Exception { byte[] data = zkClient.getData("/eclipse", false, null); System.out.println(new String(data)); } //删除znode // @Test public void deleteZnode() throws Exception { //参数2:指定要删除的版本,-1表示删除所有版本 zkClient.delete("/eclipse", -1); } //删除znode @Test public void setData() throws Exception { zkClient.setData("/app1", "imissyou angelababy".getBytes(), -1); byte[] data = zkClient.getData("/app1", false, null); System.out.println(new String(data)); } }
2. 用zookeeper实现 client监听集群服务器的心跳的功能。
package cn.itcast.bigdata.zkdist; 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 DistributedClient { private static final String connectString = "h42:2181,h43:2181"; private static final int sessionTimeout = 2000; private static final String parentNode = "/servers"; // 注意:加volatile的意义何在? private volatile List<String> serverList; private ZooKeeper zk = null; /** * 创建到zk的客户端连接 * * @throws Exception */ public void getConnect() throws Exception { zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() { @Override public void process(WatchedEvent event) { // 收到事件通知后的回调函数(应该是我们自己的事件处理逻辑) try { //重新更新服务器列表,并且注册了监听 getServerList(); } catch (Exception e) { } } }); } /** * 获取服务器信息列表 * * @throws Exception */ public void getServerList() throws Exception { // 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); // 先创建一个局部的list来存服务器信息 List<String> servers = new ArrayList<String>(); for (String child : children) { // child只是子节点的节点名 byte[] data = zk.getData(parentNode + "/" + child, false, null); System.out.println(new String(data)); servers.add(new String(data)); } // 把servers赋值给成员变量serverList,已提供给各业务线程使用 serverList = servers; //打印服务器列表 System.out.println(serverList); } /** * 业务功能 * * @throws InterruptedException */ public void handleBussiness() throws InterruptedException { System.out.println("client start working....."); Thread.sleep(Long.MAX_VALUE); } public static void main(String[] args) throws Exception { // 获取zk连接 DistributedClient client = new DistributedClient(); client.getConnect(); // 获取servers的子节点信息(并监听),从中获取服务器信息列表 client.getServerList(); // 业务线程启动 client.handleBussiness(); } }
package cn.itcast.bigdata.zkdist; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooDefs.Ids; import org.apache.zookeeper.ZooKeeper; public class DistributedServer { private static final String connectString = "h43:2181,h42:2181"; private static final int sessionTimeout = 2000; private static final String parentNode = "/servers"; private ZooKeeper zk = null; /** * 创建到zk的客户端连接 * * @throws Exception */ public void getConnect() throws Exception { zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() { @Override public void process(WatchedEvent event) { // 收到事件通知后的回调函数(应该是我们自己的事件处理逻辑) System.out.println(event.getType() + "---" + event.getPath()); try { zk.getChildren("/", true); } catch (Exception e) { } } }); } /** * 向zk集群注册服务器信息 * * @param hostname * @throws Exception */ public void registerServer(String hostname) throws Exception { //需要先在zk里面创建 /servers 节点 String create = zk.create(parentNode + "/server", hostname.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL_SEQUENTIAL); System.out.println(hostname + "is online.." + create); } /** * 业务功能 * * @throws InterruptedException */ public void handleBussiness(String hostname) throws InterruptedException { System.out.println(hostname + "start working....."); Thread.sleep(Long.MAX_VALUE); } public static void main(String[] args) throws Exception { // 获取zk连接 DistributedServer server = new DistributedServer(); server.getConnect(); // 利用zk连接注册服务器信息 server.registerServer(args[0]); // 启动业务功能 server.handleBussiness(args[0]); } }
也可以在上面的基础上继续实现负载均衡。
打jar 包放在服务器上
java -jar server.jar h42 启动