2019独角兽企业重金招聘Python工程师标准>>>
1、读取数据
构建操作包装类(Builder): GetDataBuilder getData() ---- CuratorFramework
GetDataBuilder
-
storingStatIn(org.apache.zookeeper.data.Stat stat) // 把服务器端获取的状态数据存储到stat对象
-
Byte[] forPath (String path) // 节点路劲
public void readNode(String path) throws Exception {
Stat stat = new Stat();
byte[] data = client.getData().storingStatIn(stat).forPath(path);
System.out.println("读取节点" + path + "的数据:" + new String(data));
System.out.println(stat.toString());
}
2、更新数据
构建操作包装类 (Builder) SetDataBuilder setData() ---- CuratorFramework
SetDataBuilder
-
withVersion (int version) // 特定版本号
-
forPath (String path, byte[] data) // 节点路劲
-
forPath (String path) // 节点路劲
public void updateNode(String path, byte[] data, int version)
throws Exception {
client.setData().withVersion(version).forPath(path, data);
}
3、读取子节点
构建操作包装类(Builder):GetChildrenBuilder getChildren() --- CuratorFramework
GetChildrenBuilder
-
storingStatIn(org.apache.zookeeper.data.Stat stat) // 把服务器端获取的状态数据存储到stat对象
-
Byte[] forPath(String path) // 节点路径
-
usingWatcher(org.apache.zookeeper.Watcher watcher) // 设置watcher ,类似zk本身api ,也只能使用一次
-
usingWatcher(CuratorWatcher watcher) // 设置watcher ,类似于zk本身的api,也只能使用一次
public void getChildren(String path) throws Exception {
List<String> children = client.getChildren().usingWatcher(new WatcherTest()).forPath("/curator");
for (String pth : children) {
System.out.println("child=" + pth);
}
}
4、设置watcher
1、 NodeCache
-
监听数据节点的内容变更
-
监听节点的创建,即如果指定的节点不存在,则节点创建后,会触发这个监听
2、PathChildrenCache
-
监听指定节点的子节点变化情况
-
包括:新增子节点 子节点数据变更和子节点删除
3、 NodeCache介绍
构造函数
-
NodeCache(CuratorFramework client, String path)
-
NodeCache(CuratorFramework client, String path, boolean dataIsCompressed)
client : 客户端实例
path : 数据节点路径
dataIsCompressed : 是否进行数据压缩
- 回调接口
public interface NodeCacheListener {
// 没有参数,怎么获取事件信息以及节点数据
void nodeChanged() throws Exception;
}
4、PathChildrenCache介绍
1、 构造函数
public PathChildrenCache(CuratorFramework client, String path, boolean cacheData) {
this(client, path, cacheData, false, new CloseableExecutorService(Executors.newSingleThreadExecutor(defaultThreadFactory), true));
}
public PathChildrenCache(CuratorFramework client, String path, boolean cacheData, ThreadFactory threadFactory) {
this(client, path, cacheData, false, new CloseableExecutorService(Executors.newSingleThreadExecutor(threadFactory), true));
}
public PathChildrenCache(CuratorFramework client, String path, boolean cacheData, boolean dataIsCompressed, ThreadFactory threadFactory) {
this(client, path, cacheData, dataIsCompressed, new CloseableExecutorService(Executors.newSingleThreadExecutor(threadFactory), true));
}
public PathChildrenCache(CuratorFramework client, String path, boolean cacheData, boolean dataIsCompressed, ExecutorService executorService) {
this(client, path, cacheData, dataIsCompressed, new CloseableExecutorService(executorService));
}
2、 回调接口
public interface PathChildrenCacheListener {
void childEvent(CuratorFramework var1, PathChildrenCacheEvent var2) throws Exception;
}
3、 构造函数参数
client : 客户端实例
path : 数据节点路径
dataIsCompressed : 是否进行数据压缩
cacheData : 用于配置是否把节点内容缓存起来,如果配置true,那么客户端在接收到节点列表变更时,也
能够获取到节点的数据内容,如果为false则无法取到数据内容
threadFactory : 通过这两个参数构造专门的线程池来处理事件通知
ExecutorService
4、 监听接口
public static enum Type {
CHILD_ADDED, // 新增子节点(CHILD_ADDED)
CHILD_UPDATED, // 子节点数据变更(CHILD_UPDATED)
CHILD_REMOVED, // 子节点删除(CHILD_REMOVED)
CONNECTION_SUSPENDED,
CONNECTION_RECONNECTED,
CONNECTION_LOST,
INITIALIZED;
private Type() {
}
}
5、 PathChildrenCache.StartMode
public static enum StartMode {
// 异步初始化cache
NORMAL,
// 同步初始化客户端的cache,及创建cache后,就从服务器端拉入对应的数据
BUILD_INITIAL_CACHE,
// 异步初始化,初始化完成触发事件, PathChildrenCacheEvent.Type.INITIALIZED
POST_INITIALIZED_EVENT;
private StartMode() {
}
}
6、 代码演示
public void addChildWatcher(String path) throws Exception {
final PathChildrenCache cache = new PathChildrenCache(this.client,
path, true);
cache.start(StartMode.POST_INITIALIZED_EVENT);
System.out.println(cache.getCurrentData().size());
//byte childone[] = cache.getCurrentData().get(0).getData();
// System.out.println("childone:"
// + cache.getCurrentData().get(0).getPath() + ";data="
// + new String(childone));
cache.getListenable().addListener(new PathChildrenCacheListener() {
public void childEvent(CuratorFramework client,
PathChildrenCacheEvent event) throws Exception {
if(event.getType().equals(PathChildrenCacheEvent.Type.INITIALIZED)){
System.out.println("客户端子节点cache初始化数据完成");
System.out.println("size="+cache.getCurrentData().size());
}else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_ADDED)){
System.out.println("添加子节点:"+event.getData().getPath());
System.out.println("修改子节点数据:"+new String(event.getData().getData()));
}else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_REMOVED)){
System.out.println("删除子节点:"+event.getData().getPath());
}else if(event.getType().equals(PathChildrenCacheEvent.Type.CHILD_UPDATED)){
System.out.println("修改子节点数据:"+event.getData().getPath());
System.out.println("修改子节点数据:"+new String(event.getData().getData()));
}
}
});
}