How to convert a Hadoop Path object into a Java File object

Question

Is there a way to change a valid and existing Hadoop Path object into a useful Java File object. Is there a nice way of doing this or do I need to bludgeon to code into submission? The more obvious approaches don't work, and it seems like it would be a common bit of code

void func(Path p) {
  if (p.isAbsolute()) {
     File f = new File(p.toURI());
  }
}

This doesn't work because Path::toURI() returns the "hdfs" identifier and Java's File(URI uri) constructor only recognizes the "file" identifier.

Is there a way to get Path and File to work together?

**

Ok, how about a specific limited example.

Path[] paths = DistributedCache.getLocalCacheFiles(job);

DistributedCache is supposed to provide a localized copy of a file, but it returns a Path. I assume that DistributedCache make a local copy of the file, where they are on the same disk. Given this limited example, where hdfs is hopefully not in the equation, is there a way for me to reliably convert a Path into a File?

**

Answer 1

I recently had this same question, and there really is a way to get a file from a path, but it requires downloading the file temporarily. Obviously, this won't be suitable for many tasks, but if time and space aren't essential for you, and you just need something to work using files from Hadoop, do something like the following:

import java.io.File;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public final class PathToFileConverter {
    public static File makeFileFromPath(Path some_path, Configuration conf) throws IOException {
        FileSystem fs = FileSystem.get(some_path.toUri(), conf);
        File temp_data_file = File.createTempFile(some_path.getName(), "");
        temp_data_file.deleteOnExit();
        fs.copyToLocalFile(some_path, new Path(temp_data_file.getAbsolutePath()));
        return temp_data_file;
    }
}

Answer 2

If you get a LocalFileSystem

final LocalFileSystem localFileSystem = FileSystem.getLocal(configuration);

You can pass your hadoop Path object to localFileSystem.pathToFile

final File localFile = localFileSystem.pathToFile(<your hadoop Path>);