storm-hdfs RotationActions 接口用法

storm-hdfs 这个插件支持  Rotation Actions 这个功能，官方文档解释是这样的，

### File Rotation Actions

Both the HDFS bolt and Trident State implementation allow you to register any number of `RotationAction`s.

What `RotationAction`s do is provide a hook to allow you to perform some action right after a file is rotated. For

example, moving a file to a different location or renaming it.

大概意思就是，写完hdfs文件之后会调用这个注册的方法，可以做个善后工作，比如移动个文件夹啥的。官方给了个例子，MoveFileAction 也是当文件写完之后移动到另外一个文件夹中，可是坑爹的是这个类不好用。于是没办法只能自己手动写一个了，把这个公布出来大家一起分享。

package lanbo.storm.kafka.examples;

import org.apache.commons.io.IOUtils;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.storm.hdfs.common.rotation.RotationAction;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Created by lanbo on 15-2-13.
 */
public class CopyFileAction implements RotationAction {
    private static final Logger LOG = LoggerFactory.getLogger(CopyFileAction.class);

    private String destination;

    public CopyFileAction toDestination(String destDir){
        destination = destDir;
        return this;
    }

    @Override
    public void execute(FileSystem fileSystem, Path filePath) throws IOException {
        Path destPath = new Path(destination, filePath.getName());
        LOG.info("Moving file {} to {}", filePath, destPath);
        InputStream ins = fileSystem.open(filePath);
        OutputStream os = fileSystem.create(destPath);
        try{
            IOUtils.copy(ins, os);
            fileSystem.delete(filePath,true);
        }catch(Exception e){
            throw new IOException(e);
        }finally{
            ins.close();
            os.close();

        }

        return;
    }
}

这个类简单的就能实现移动文件夹，以后会陆续更新很多更有用的工具