ZooKeeper实际应用讲解
编程语言
2019-02-25 17:44:19
阅读次数: 0
在IDEA上安装ZooKeeper插件
- 首先在IDEA中下载ZooKeeper插件
- 对ZooKeeper插件进行配置
- 之后会在界面的左上角找到ZooKeeper的操作界面
ZooKeeper实际场景
- 我们希望ZooKeeper对分布式系统的配置进行管理，也就是说多个服务器进行watcher，ZooKeeper结点发送变化，则我们实时更新配置文件
- 我们要完成多个应用服务器注册watcher，然后去实时的观察数据的变化，然后反馈给媒体服务器变更的数据信息。观察ZooKeeper节点
代码实例
- 代码目录结构
-
package bhz.zookeeper.cluster;
import bhz.zookeeper.cluster.ZKWatcher;
public class Client1 {
public static void main(String[] args) throws Exception{
ZKWatcher myWatcher = new ZKWatcher();
Thread.sleep(100000000);
}
}
-
package bhz.zookeeper.cluster;
import bhz.zookeeper.cluster.ZKWatcher;
public class Client2 {
public static void main(String[] args) throws Exception{
ZKWatcher myWatcher = new ZKWatcher();
Thread.sleep(100000000);
}
}
-
package bhz.zookeeper.cluster;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
public class Test {
/** zookeeper地址 */
static final String CONNECT_ADDR = "172.20.10.4:2181";
/** session超时时间 */
static final int SESSION_OUTTIME = 2000;//ms
/** 信号量，阻塞程序执行，用于等待zookeeper连接成功，发送成功信号 */
static final CountDownLatch connectedSemaphore = new CountDownLatch(1);
public static void main(String[] args) throws Exception{
ZooKeeper zk = new ZooKeeper(CONNECT_ADDR, SESSION_OUTTIME, new Watcher(){
@Override
public void process(WatchedEvent event) {
//获取事件的状态
KeeperState keeperState = event.getState();
EventType eventType = event.getType();
//如果是建立连接
if(KeeperState.SyncConnected == keeperState){
if(EventType.None == eventType){
//如果建立连接成功，则发送信号量，让后续阻塞程序向下执行
connectedSemaphore.countDown();
System.out.println("zk 建立连接");
}
}
}
});
//进行阻塞
connectedSemaphore.await();
// //创建子节点
zk.create("/super/c1", "c1".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//创建子节点
zk.create("/super/c2", "c2".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//创建子节点
zk.create("/super/c3", "c3".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//创建子节点
zk.create("/super/c4", "c4".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
// zk.create("/super/c4/c44", "c44".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
//获取节点信息
// byte[] data = zk.getData("/testRoot", false, null);
// System.out.println(new String(data));
// System.out.println(zk.getChildren("/testRoot", false));
//修改节点的值
zk.setData("/super/c1", "modify c1".getBytes(), -1);
zk.setData("/super/c2", "modify c2".getBytes(), -1);
byte[] data = zk.getData("/super/c2", false, null);
System.out.println(new String(data));
//判断节点是否存在
System.out.println(zk.exists("/super/c3", false));
//删除节点
zk.delete("/super/c3", -1);
zk.close();
}
}
-
package bhz.zookeeper.cluster;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
public class ZKWatcher implements Watcher {
/** zk变量 */
private ZooKeeper zk = null;
/** 父节点path */
static final String PARENT_PATH = "/super";
/** 信号量设置，用于等待zookeeper连接建立之后 通知阻塞程序继续向下执行 */
private CountDownLatch connectedSemaphore = new CountDownLatch(1);
private List<String> cowaList = new CopyOnWriteArrayList<String>();
/** zookeeper服务器地址 */
public static final String CONNECTION_ADDR = "172.20.10.4:2181";
/** 定义session失效时间 */
public static final int SESSION_TIMEOUT = 30000;
public ZKWatcher() throws Exception{
zk = new ZooKeeper(CONNECTION_ADDR, SESSION_TIMEOUT, this);
System.out.println("开始连接ZK服务器");
connectedSemaphore.await();
}
@Override
public void process(WatchedEvent event) {
// 连接状态
KeeperState keeperState = event.getState();
// 事件类型
EventType eventType = event.getType();
// 受影响的path
String path = event.getPath();
System.out.println("受影响的path : " + path);
if (KeeperState.SyncConnected == keeperState) {
// 成功连接上ZK服务器
if (EventType.None == eventType) {
System.out.println("成功连接上ZK服务器");
connectedSemaphore.countDown();
try {
if(this.zk.exists(PARENT_PATH, false) == null){
this.zk.create(PARENT_PATH, "root".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
List<String> paths = this.zk.getChildren(PARENT_PATH, true);
for (String p : paths) {
System.out.println(p);
this.zk.exists(PARENT_PATH + "/" + p, true);
}
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//创建节点
else if (EventType.NodeCreated == eventType) {
System.out.println("节点创建");
try {
this.zk.exists(path, true);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//更新节点
else if (EventType.NodeDataChanged == eventType) {
System.out.println("节点数据更新");
try {
//update nodes call function
this.zk.exists(path, true);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//更新子节点
else if (EventType.NodeChildrenChanged == eventType) {
System.out.println("子节点 ... 变更");
try {
List<String> paths = this.zk.getChildren(path, true);
if(paths.size() >= cowaList.size()){
paths.removeAll(cowaList);
for(String p : paths){
this.zk.exists(path + "/" + p, true);
//this.zk.getChildren(path + "/" + p, true);
System.out.println("这个是新增的子节点 : " + path + "/" + p);
//add new nodes call function
}
cowaList.addAll(paths);
} else {
cowaList = paths;
}
System.out.println("cowaList: " + cowaList.toString());
System.out.println("paths: " + paths.toString());
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
//删除节点
else if (EventType.NodeDeleted == eventType) {
System.out.println("节点 " + path + " 被删除");
try {
//delete nodes call function
this.zk.exists(path, true);
} catch (KeeperException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
else ;
}
else if (KeeperState.Disconnected == keeperState) {
System.out.println("与ZK服务器断开连接");
}
else if (KeeperState.AuthFailed == keeperState) {
System.out.println("权限检查失败");
}
else if (KeeperState.Expired == keeperState) {
System.out.println("会话失效");
}
else ;
System.out.println("--------------------------------------------");
}
}
转载自blog.csdn.net/Future_LL/article/details/87913476