使用JAVA & Zookeeper构建分布式键值存储
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooKeeper;
import org.apache.zookeeper.data.Stat;
public class DistributedKeyValueStore {
private final ZooKeeper zk;
private final String rootPath;
public DistributedKeyValueStore(String hosts, String rootPath) throws Exception {
this.zk = new ZooKeeper(hosts, 3000, event -> {});
this.rootPath = rootPath;
if (this.zk.exists(rootPath, false) == null) {
this.zk.create(rootPath, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
}
public void set(String key, String value) throws Exception {
String path = rootPath + "/" + key;
if (this.zk.exists(path, false) == null) {
this.zk.create(path, value.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
} else {
this.zk.setData(path, value.getBytes(), -1);
}
}
public String get(String key) throws Exception {
Stat stat = this.zk.exists(rootPath + "/" + key, false);
if (stat != null) {
return new String(this.zk.getData(rootPath + "/" + key, false, stat));
}
return null;
}
public void close() throws InterruptedException {
this.zk.close();
}
public static void main(String[] args) {
try {
DistributedKeyValueStore store = new DistributedKeyValueStore("localhost:2181", "/kvstore");
store.set("key1", "value1");
String value = store.get("key1");
System.out.println("Retrieved value for 'key1': " + value);
store.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
这段代码提供了一个简单的分布式键值存储的实现,它使用Zookeeper作为底层的存储系统。它展示了如何创建一个键值存储,如何设置和获取键值对,以及如何关闭与Zookeeper的连接。这个例子是基于Zookeeper的原生API,并且为了简洁起见,省略了异常处理和其他辅助方法。
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