ReadOnlyHttpFileSystem.java

import org.apache.commons.lang.NotImplementedException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.util.Progressable;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;

public class ReadOnlyHttpFileSystem extends FileSystem {
    private URI uri;
    private Path path;
    private static final long DEFAULT_BLOCK_SIZE = 4 * 1024;

    @Override
    public void initialize(URI uri, Configuration conf) throws IOException {
        this.uri = uri;
    }

    @Override
    public URI getUri() {
        return uri;
    }

    @Override
    public FSDataInputStream open(Path path, int i) throws IOException {
        this.path = path;
        URL url = new URL(uri.toString());
        InputStream inputStream = url.openStream();
        BufferedInputStream bufferedInput = new BufferedInputStream(inputStream);
        return new FSDataInputStream(bufferedInput);
    }

    @Override
    public FSDataOutputStream create(Path path, FsPermission fsPermission, boolean b, int i, short s, long l, Progressable progressable) throws IOException {
        throw new NotImplementedException("Cannot create path");
    }

    @Override
    public FSDataOutputStream append(Path path, int i, Progressable progressable) throws IOException {
        throw new NotImplementedException("Cannot append to path");
    }

    @Override
    public boolean rename(Path path, Path path1) throws IOException {
        throw new NotImplementedException("Cannot rename path");
    }

    @Override
    public boolean delete(Path path) throws IOException {
        throw new NotImplementedException("Cannot delete path");
    }

    @Override
    public boolean delete(Path path, boolean b) throws IOException {
        throw new NotImplementedException("Cannot delete path");
    }

    @Override
    public FileStatus[] listStatus(Path path) throws IOException {
        return new FileStatus[]{ createFileStatus(path) };
    }

    @Override
    public void setWorkingDirectory(Path path) {
    }

    @Override
    public Path getWorkingDirectory() {
        return this.path;
    }

    @Override
    public boolean mkdirs(Path path, FsPermission fsPermission) throws IOException {
        throw new NotImplementedException("Cannot make directory");
    }

    @Override
    public FileStatus getFileStatus(Path path) throws IOException {
        return createFileStatus(path);
    }

    private FileStatus createFileStatus(Path path) throws IOException {
        URL url = new URL(uri.toString());
        URLConnection urlConnection = url.openConnection();        
        return new FileStatus(urlConnection.getContentLength(), false, 1, DEFAULT_BLOCK_SIZE, urlConnection.getLastModified(), path);
    }
}