Java Spring Boot 集成Zookeeper
作者：剑圣无痕
这篇文章主要介绍了Java Spring Boot 集成Zookeeper，文章围绕主题展开详细的内容介绍，具有一定的参考价值，需要的小伙伴可以参考一下
集成步骤
1.pom.xml文件配置，引入相关jar包
Curator是Netflix公司开源的一套zookeeper客户端框架，解决了很多Zookeeper客户端非常底层的细节开发工作，包括连接重连、反复注册Watcher和NodeExistsException异常等等。
<!-- 封装了一些高级特性，如：Cache事件监听、选举、分布式锁、分布式Barrier -->
<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-recipes</artifactId>
<version>2.10.0</version>
<exclusions>
<exclusion>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.4.13</version>
<exclusions>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
</exclusion>
<exclusion>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</exclusion>
<exclusion>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>特殊说明： 1.无需引入curator-framework，因为curator-recipes自动关联依赖引入curator-framework。 2.curator会默认引入zookeeper的jar报，需要检查版本与服务器的版本是否一致，如果不一致则需要排除引入 3.
2. 核心配置类
@Configuration
public class ZookeeperConfig implements Serializable
{
private static final long serialVersionUID = -9025878246972668136L;
private final ZooKeeperProperty zooKeeperProperty;
public ZookeeperConfig(ZooKeeperProperty zooKeeperProperty) {
this.zooKeeperProperty = zooKeeperProperty;
}
@Bean
public CuratorFramework curatorFramework()
{
RetryPolicy retryPolicy = new ExponentialBackoffRetry(zooKeeperProperty.getBaseSleepTime(),
zooKeeperProperty.getMaxRetries());
CuratorFramework client = CuratorFrameworkFactory.builder()
.connectString(zooKeeperProperty.getServers())
.connectionTimeoutMs(zooKeeperProperty.getConnectionTimeout())
.sessionTimeoutMs(zooKeeperProperty.getSessionTimeout())
.retryPolicy(retryPolicy)
.build();
client.start();
return client;
}
@Bean
@ConditionalOnMissingBean
public ZooKeeperUtils zooKeeperTemplate(CuratorFramework client) {
return new ZooKeeperUtils(client);
}
}
@ConfigurationProperties(prefix="zookeeper")
@Component
public class ZooKeeperProperty implements Serializable
{
private static final long serialVersionUID = 8650758711482699256L;
/**
* zk连接集群，多个用逗号隔开
*/
private String servers;
/**
* 会话超时时间
*/
private int sessionTimeout = 60000;
/**
* 连接超时时间
*/
private int connectionTimeout = 15000;
/**
* 初始重试等待时间(毫秒)
*/
private int baseSleepTime = 1000;
/**
* 重试最大次数
*/
private int maxRetries = 10;
//省略get、set方法
......
}3.常用API功能
@Component
public class ZooKeeperUtils
{
private static final Logger logger = LoggerFactory
.getLogger(ZooKeeperUtils.class);
/**
* 路径分隔符
*/
private static final String PATH_SEPARATOR = "/";
/**
* zk连接
*/
private final CuratorFramework client;
public ZooKeeperUtils(CuratorFramework client)
{
this.client = client;
}
/**
* 创建空节点，默认持久节点
*
* @param path
* 节点路径
* @param node
* 节点名称
* @return 完整路径
*/
public String createNode(String path, String node)
{
return createNode(path, node, CreateMode.PERSISTENT);
}
/**
* 创建带类型的空节点
*
* @param path
* 节点路径
* @param node
* 节点名称
* @param createMode
* 类型 CreateMode.PERSISTENT: 创建节点后，不删除就永久存在
* CreateMode.PERSISTENT_SEQUENTIAL：节点path末尾会追加一个10位数的单调递增的序列
* CreateMode.EPHEMERAL：创建后，回话结束节点会自动删除
* CreateMode.EPHEMERAL_SEQUENTIAL：节点path末尾会追加一个10位数的单调递增的序列
* @return 路径
*/
public String createNode(String path, String node, CreateMode createMode)
{
path = buildPath(path, node);
logger.info("create node for path: {} with createMode: {}", path,
createMode.name());
try
{
client.create().creatingParentsIfNeeded().withMode(createMode)
.forPath(path);
logger.info("create node :{} sucessfully", node);
return path;
}
catch (Exception e)
{
logger.error(
"create node for path: {} with createMode: {} failed!",
path, createMode.name(), e);
return null;
}
}
/**
* 创建节点，默认持久节点
*
* @param path
* 节点路径
* @param node
* 节点名称
* @param value
* 节点值
* @return 完整路径
*/
public String createNode(String path, String node, String value)
{
return createNode(path, node, value, CreateMode.PERSISTENT);
}
/**
* 创建节点，默认持久节点
*
* @param path
* 节点路径
* @param node
* 节点名称
* @param value
* 节点值
* @param createMode
* 节点类型
* @return 完整路径
*/
public String createNode(String path, String node, String value,
CreateMode createMode)
{
if (Objects.isNull(value))
{
logger.error("ZooKeeper节点值不能为空!");
}
path = buildPath(path, node);
logger.info("create node for path: {}, value: {}, with createMode: {}",
path, value, createMode.name());
try
{
client.create().creatingParentsIfNeeded().withMode(createMode)
.forPath(path, value.getBytes());
return path;
}
catch (Exception e)
{
logger.error(
"create node for path: {}, value: {}, with createMode: {} failed!",
path, value, createMode.name(), e);
}
return null;
}
/**
* 获取节点数据
*
* @param path
* 路径
* @param node
* 节点名称
* @return 完整路径
*/
public String get(String path, String node)
{
path = buildPath(path, node);
try
{
byte[] bytes = client.getData().forPath(path);
if (bytes.length > 0)
{
return new String(bytes);
}
}
catch (Exception e)
{
logger.error("get value for path: {}, node: {} failed!", path,
node, e);
}
return null;
}
/**
* 更新节点数据
*
* @param path
* 节点路径
* @param node
* 节点名称
* @param value
* 更新值
* @return 完整路径
*/
public String update(String path, String node, String value)
{
if (Objects.isNull(value))
{
logger.error("ZooKeeper节点值不能为空!");
}
path = buildPath(path, node);
logger.info("update path: {} to value: {}", path, value);
try
{
client.setData().forPath(path, value.getBytes());
return path;
}
catch (Exception e)
{
logger.error("update path: {} to value: {} failed!", path, value);
}
return null;
}
/**
* 删除节点，并且递归删除子节点
*
* @param path
* 路径
* @param node
* 节点名称
* @return 路径
*/
public boolean delete(String path, String node)
{
path = buildPath(path, node);
logger.info("delete node for path: {}", path);
try
{
client.delete().deletingChildrenIfNeeded().forPath(path);
return true;
}
catch (Exception e)
{
logger.error("delete node for path: {} failed!", path);
}
return false;
}
/**
* 获取子节点
*
* @param path
* 节点路径
* @return
*/
public List<String> getChildren(String path)
{
if (StringUtils.isEmpty(path))
{
return null;
}
if (!path.startsWith(PATH_SEPARATOR))
{
path = PATH_SEPARATOR + path;
}
try
{
return client.getChildren().forPath(path);
}
catch (Exception e)
{
logger.error("get children path:{} error", path, e);
}
return null;
}
/**
* 判断节点是否存在
*
* @param path
* 路径
* @param node
* 节点名称
* @return 结果
*/
public boolean exists(String path, String node)
{
try
{
List<String> list = getChildren(path);
return !CollectionUtils.isEmpty(list) && list.contains(node);
}
catch (Exception e)
{
return false;
}
}
/**
* 申请锁，指定请求等待时间
*
* @param path
* 加锁zk节点
* @param time
* 时间
* @param unit
* 时间单位
* @param runnable
* 执行方法
*/
public void lock(String path, long time, TimeUnit unit, Runnable runnable)
{
try
{
InterProcessMutex lock = new InterProcessMutex(client, path);
if (lock.acquire(time, unit))
{
try
{
runnable.run();
}
finally
{
lock.release();
}
}
else
{
logger.error("获取锁超时：{}!", path);
}
}
catch (Exception e)
{
logger.error("获取锁失败: {}!", path);
}
}
/**
* 申请锁，指定请求等待时间
*
* @param path
* 加锁zk节点
* @param time
* 时间
* @param unit
* 时间单位
* @param callable
* 执行方法
* @return .
*/
public <T> T lock(String path, long time, TimeUnit unit,
Callable<T> callable)
{
try
{
InterProcessMutex lock = new InterProcessMutex(client, path);
if (lock.acquire(time, unit))
{
try
{
return callable.call();
}
finally
{
lock.release();
}
}
else
{
logger.error("获取锁超时：{}!", path);
}
}
catch (Exception e)
{
logger.error("获取锁失败: {}!", path);
}
return null;
}
/* *//**
* 对一个节点进行监听，监听事件包括指定的路径节点的增、删、改的操作
*
* @param path
* 节点路径
* @param listener
* 回调方法
* @throws Exception
*/
public void watchNode(String path,boolean dataIsCompressed,final ZooKeeperCallback zooKeeperCallback)throws Exception
{
try
{
final NodeCache nodeCache = new NodeCache(client, path,dataIsCompressed);
nodeCache.getListenable().addListener(new NodeCacheListener()
{
public void nodeChanged() throws Exception
{
ChildData childData = nodeCache.getCurrentData();
logger.info("ZNode节点状态改变, path={}", childData.getPath());
logger.info("ZNode节点状态改变, data={}", childData.getData());
logger.info("ZNode节点状态改变, stat={}", childData.getStat());
//处理业务逻辑
zooKeeperCallback.call();
}
});
nodeCache.start();
}
catch (Exception e)
{
logger.error("创建NodeCache监听失败, path={}",path);
}
}
/**
* 对指定的路径节点的一级子目录进行监听，不对该节点的操作进行监听，对其子目录的节点进行增、删、改的操作监听
*
* @param path
* 节点路径
* @param listener
* 回调方法
*/
public void watchChildren(String path, PathChildrenCacheListener listener)
{
try
{
PathChildrenCache pathChildrenCache = new PathChildrenCache(client,
path, true);
pathChildrenCache.start(PathChildrenCache.StartMode.NORMAL);
pathChildrenCache.getListenable().addListener(listener);
}
catch (Exception e)
{
logger.error("watch children failed for path: {}", path, e);
}
}
/**
* 将指定的路径节点作为根节点（祖先节点），对其所有的子节点操作进行监听，呈现树形目录的监听，可以设置监听深度，最大监听深度为2147483647（
* int类型的最大值）
*
* @param path
* 节点路径
* @param maxDepth
* 回调方法
* @param listener
* 监听
*/
public void watchTree(String path, int maxDepth, TreeCacheListener listener)
{
try
{
TreeCache treeCache = TreeCache.newBuilder(client, path)
.setMaxDepth(maxDepth).build();
treeCache.start();
treeCache.getListenable().addListener(listener);
}
catch (Exception e)
{
logger.error("watch tree failed for path: {}", path, e);
}
}
public String buildPath(String path, String node)
{
if (StringUtils.isEmpty(path) || StringUtils.isEmpty(node))
{
logger.error("ZooKeeper路径或者节点名称不能为空！");
}
if (!path.startsWith(PATH_SEPARATOR))
{
path = PATH_SEPARATOR + path;
}
if (PATH_SEPARATOR.equals(path))
{
return path + node;
}
else
{
return path + PATH_SEPARATOR + node;
}
}
}4.基本使用
@Autowired
private ZooKeeperUtils zooKeeperUtil;
@RequestMapping("/addNode")
public String addNode()
{
String path= zooKeeperUtil.createNode("/zookeeper", "node1");
return path;
}特殊说明：关于zookeeper的分布式锁，后续讲解常用分布式锁的时候，会详细说明。
常见错误和解决办法
问题1：调用api创建zookeeper节点时，报KeeperErrorCode = Unimplemented for /test错误。
原因：服务器安装zookeeper的版本与程序中的zookeeper版本不一致。
解决方案： 登录服务器，查看zookeeper安装版本，执行如下命令：
echo stat|nc 127.0.0.1 2181
当前引入的zookeeper版本为3.4.13，而zookeeper的版本与curator对应关系如下：
Curator 2.x.x - compatible with both ZooKeeper 3.4.x and ZooKeeper 3.5.x Curator 4.x.x - compatible only with ZooKeeper 3.5.x and includes support for new features such as dynamic reconfiguration, etc. Curator 5.x.x compatible only with ZooKeeper 3.6.x+
问题2：启动项目的日志中会有Will not attempt to authenticate using SASL错误
起初我认为是zookeeper需要进行SASL认证，但是通过查阅相关资料后，才知道3.4之前版本，zookeeper默认会采用SASL认证,3.4以后的版本没有此类问题。
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