Hadoop清理空间
 throws IOException {
conf = new Configuration();
fs = FileSystem.get(conf);
}
public void cleanExpiredData(String dataPath, long expirationTime) throws IOException {
Path path = new Path(dataPath);
FileStatus[] fileStatuses = fs.listStatus(path);
for (FileStatus fileStatus : fileStatuses) {
if (fileStatus.getModificationTime() < expirationTime) {
fs.delete(fileStatus.getPath(), true);
}
}
}
public static void main(String[] args) throws IOException {
ExpiredDataCleaner cleaner = new ExpiredDataCleaner();
cleaner.cleanExpiredData("/path/to/data", System.currentTimeMillis() - TimeUnit.DAYS.toMillis(30));
}
}
上述代码中,cleanExpiredData
方法接受一个数据路径和一个过期时间作为参数。它列出给定路径下的所有文件,并删除修改时间在过期时间之前的文件。
2. 压缩数据
除了直接删除过期数据,另一种常见的方法是压缩数据。通过压缩数据,可以减少存储空间的占用,并提高数据读取和传输的效率。
Hadoop提供了多种压缩算法和编解码器,如Gzip、Snappy和LZO。下面是一个示例代码,演示了如何使用Snappy编解码器来压缩Hadoop集群中的数据:
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.SnappyCodec;
public class DataCompressor {
private Configuration conf;
private FileSystem fs;
public DataCompressor() throws IOException {
conf = new Configuration();
fs = FileSystem.get(conf);
}
public void compressData(String dataPath) throws IOException {
Path path = new Path(dataPath);
CompressionCodec codec = new SnappyCodec();
// 压缩文件
Path compressedPath = new Path(dataPath + ".snappy");
InputStream in = fs.open(path);
OutputStream out = codec.createOutputStream(fs.create(compressedPath));
IOUtils.copyBytes(in, out, conf);
// 删除原文件
fs.delete(path, true);
// 重命名压缩文件
fs.rename(compressedPath, path);
}
public static void main(String[] args) throws IOException {
DataCompressor compressor = new DataCompressor();
compressor.compressData("/path/to/data");
}
}
上述代码中,compressData
方法接受一个数据路径作为参数,并使用Snappy编解码器压缩数据。压缩后,原始文件将被删除,并用压缩文件进行替换。
类图
以下是本文介绍的两个示例类的类图:
classDiagram
class ExpiredDataCleaner {
- Configuration conf
- FileSystem fs
+ ExpiredDataCleaner()
+ cleanExpiredData(dataPath: String, expirationTime: long)
+ main(args: String[])
}
class DataCompressor {
- Configuration conf
- FileSystem fs
+ DataCompressor()
+ compressData(dataPath: String)
+ main(args: String[])
}
上述类图展示了`Expired