通过Java代码获取Zookeeper服务器状态

有的时候，我们想知道Zookeeper集群中哪些服务器属于Leader，哪些属于Follower，哪些属于Observer。

通过命令，可以很容易的获取到Zookeeper服务器的状态：

[hadoop@hadoopcluster84 bin]$ ./zkServer.sh status
JMX enabled by default
Using config: /home/hadoop/apache/zookeeper-3.4.5/bin/../conf/zoo.cfg
Mode: follower

下面我们用Java代码来获取Zookeeper服务器的状态：
public class ServerStatus {
@Test
public void serverStatus() throws IOException {
String host = "10.0.1.84";
int port = 2181;
String cmd = "stat";

Socket sock = new Socket(host, port);
BufferedReader reader = null;
try {
OutputStream outstream = sock.getOutputStream();
// 通过Zookeeper的四字命令获取服务器的状态
outstream.write(cmd.getBytes());
outstream.flush();
sock.shutdownOutput();

reader = new BufferedReader(new InputStreamReader(sock.getInputStream()));
String line;
while ((line = reader.readLine()) != null) {
if (line.indexOf("Mode: ") != -1) {
System.out.println(line.replaceAll("Mode: ", "").trim());
}
}
} finally {
sock.close();
if (reader != null) {
reader.close();
}
}
}
}

输出结果：
follower

上面的代码可以改改，通过其他四字命令获取zookeeper集群的状态。