com.neovisionaries.zookeeper

Class NodeReader

java.lang.Object

com.neovisionaries.zookeeper.NodeReader

public class NodeReader
extends Object

Znode reader. If the target znode to read does not exist when start() method is called, this implementation waits for the target znode to be created and then reads its content.

 // Prepare a ZooKeeper instance.
 ZooKeeper zooKeeper = ...

 // The path of the target znode to read.
 String path = ...

 // Prepare a Listener implementation.
 NodeReader.NodeReader.Listener listener = new NodeReader.Listener() {
     @Override
     public void onRead(NodeReader reader, byte[] data, Stat stat) {
         System.out.println("Successfully read the znode.");
     }

     @Override
     public void onGaveUp(NodeReader reader) {
         System.out.println("Gave up reading the znode.");
     }
 };

 // Read the target znode.
 new NodeReader()
     .setZooKeeper(zooKeeper)
     .setPath(path)
     .setListener(listener)
     .start();
 

Since:

1.2

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	NodeReader.Adapter An empty implementation of NodeReader.Listener interface.
static interface	NodeReader.Listener Listener interface to receive the result of reading.

Constructor Summary

Constructors

Constructor and Description
NodeReader()
NodeReader(org.apache.zookeeper.ZooKeeper zooKeeper)

Method Summary

Modifier and Type	Method and Description
NodeReader	finish() Mark as 'shouldFinish' not to schedule ZooKeeper callbacks any further.
NodeReader.Listener	getListener() Get the listener.
String	getPath() Get the path of the target znode to read.
org.apache.zookeeper.ZooKeeper	getZooKeeper() Get the ZooKeeper instance to read the target znode.
NodeReader	setListener(NodeReader.Listener listener) Set a listener.
NodeReader	setPath(String path) Set the path of the target znode to read.
NodeReader	setZooKeeper(org.apache.zookeeper.ZooKeeper zooKeeper) Set the ZooKeeper instance to read the target znode.
NodeReader	start() Start reading the target znode.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NodeReader

public NodeReader()

NodeReader

public NodeReader(org.apache.zookeeper.ZooKeeper zooKeeper)

Method Detail

getZooKeeper

public org.apache.zookeeper.ZooKeeper getZooKeeper()

Get the ZooKeeper instance to read the target znode.

Returns:

The ZooKeeper instance.

setZooKeeper

public NodeReader setZooKeeper(org.apache.zookeeper.ZooKeeper zooKeeper)

Set the ZooKeeper instance to read the target znode.

If no ZooKeeper instance is set when start() is called, an IllegalStateException is thrown.

Parameters:

zooKeeper - A ZooKeeper instance.

Returns:

this object.

getPath

public String getPath()

Get the path of the target znode to read.

Returns:

The path of the target znode to read.

setPath

public NodeReader setPath(String path)

Set the path of the target znode to read.

If no path is set when start() is called, an IllegalStateException is thrown.

Parameters:

path - The path of the target znode.

Returns:

this object.

getListener

public NodeReader.Listener getListener()

Get the listener.

Returns:

The listener.

setListener

public NodeReader setListener(NodeReader.Listener listener)

Set a listener.

Parameters:

listener - A listener.

Returns:

this object.

start

public NodeReader start()

Start reading the target znode.

Returns:

this object.

Throws:

IllegalStateException -

• No ZooKeeper instance is set.
• No path is set.

finish

public NodeReader finish()

Mark as 'shouldFinish' not to schedule ZooKeeper callbacks any further.

Note that calling this method does not remove an existing Watcher which is watching the target znode.

Returns:

this object.