Zookeeper04之javaAPI的使用

Java程式操作Zookeeper

1.建立java項目并導入相關jar包

主要jar包在主目錄下

項目需要的相關依賴的jar包在zookeeper的解壓檔案的lib目錄下就有

将這幾個jar包導入項目即可

maven項目坐标

<dependency>
    <groupId>org.apache.zookeeper</groupId>
    <artifactId>zookeeper</artifactId>
    <version>3.4.6</version>
    <type>pom</type>
</dependency>
<dependency>
    <groupId>com.github.sgroschupf</groupId>
    <artifactId>zkclient</artifactId>
    <version>0.1</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>      

2.API簡單使用

2.1配置Zookeeper對象

// zookeeper的伺服器位址
    private String connectString = "192.168.88.121:2181,192.168.88.122:2181,192.168.88.123:2181";
    // 連接配接逾時時間
    private int sessionTimeout = 2000;
    
    private ZooKeeper zk = null;

    /**
     * 設定zookeeper對象
     * @throws IOException 
     */
    @Before
    public void setZookeeper() throws IOException {
        
        zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
            /**
             * 事件觸發的回調方法
             */
            @Override
            public void process(WatchedEvent event) {
                
            }
        });
        System.out.println("---"+zk);
    }      

常用API操作

/**
 * create 方法參數
 *    第一個參數 路徑
 *    第二個參數  值  bytes
 *    第三個參數  對節點的通路控制
 *    第四個參數  節點的類型 短暫  永久  序号        
 * @throws KeeperException
 * @throws InterruptedException
 */
@Test
public void create() throws KeeperException, InterruptedException {
    String path = zk.create("/app3", "123".getBytes(), 
            Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    System.out.println(path);
}
/**
 * 判斷節點是否存在
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void exist() throws KeeperException, InterruptedException{
    // 設定為 true 會調用 zk中的監聽器
    Stat stat = zk.exists("/app1", true);
    if(stat!=null){
        
        System.out.println("存在。。。。"+stat.getDataLength());
    }else{
        System.out.println("不存在。。。");
    }
}
/**
 * 擷取子節點
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void getChilren() throws KeeperException, InterruptedException{
    List<String> list = zk.getChildren("/", true);
    for (String s : list) {
        System.out.println(s);
    }
}

/**
 * 擷取節點的内容
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void getData() throws KeeperException, InterruptedException{
    
    byte[] b = zk.getData("/app1", false, null );
    System.out.println(new String(b));
}

/**
 * 修改節點内容
 *    version -1 自動維護
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void setData() throws KeeperException, InterruptedException{
    Stat s = zk.setData("/app1", "test".getBytes(), -1);
}
/**
 * 删除節點
 *    
 * @throws InterruptedException
 * @throws KeeperException
 */
@Test
public void deleteNode() throws InterruptedException, KeeperException{
    zk.delete("/app1", -1);
}      

3.監聽器的使用

@Before
public static void setUpBeforeClass() throws Exception {
    zk = new ZooKeeper(connectString, sessionTimeout, new Watcher() {
        /**
         * 監聽器
         */
        @Override
        public void process(WatchedEvent event) {
            System.out.println("事件觸發...");
        }
    });
}


/**
 * 擷取子節點
 * getChildren(path,watch?)監聽的事件是：節點下的子節點增減變化事件
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void getChilren() throws KeeperException, InterruptedException{
    List<String> list = zk.getChildren("/", new Watcher() {
        
        @Override
        public void process(WatchedEvent event) {
            // TODO Auto-generated method stub
            System.out.println("監控節點下的子節點被改變..."+event.getPath());
        }
    });
    for (String s : list) {
        System.out.println(s);
    }
    Thread.sleep(Long.MAX_VALUE);
}

/**
 * 擷取節點的内容
 * getData(path,watch?)監聽的事件是：節點資料變化事件
 * @throws InterruptedException 
 * @throws KeeperException 
 */
@Test
public void getData() throws KeeperException, InterruptedException{
    
    byte[] b = zk.getData("/app1", new Watcher() {
        
        @Override
        public void process(WatchedEvent event) {
            System.out.println("--資料改變了--");
            
        }
    }, null );
    System.out.println(new String(b));
    Thread.sleep(Long.MAX_VALUE);
}      

~zookeeper的javaAPI操作還是比較簡單的，本文就介紹到這裡