HDFSRandomAccessFile.java Source code

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Here is the source code for HDFSRandomAccessFile.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import ucar.unidata.io.RandomAccessFile;

import java.io.IOException;
import java.net.URI;
import java.nio.ByteBuffer;
import java.nio.channels.WritableByteChannel;

public class HDFSRandomAccessFile extends RandomAccessFile {

    protected URI fsURI;
    protected Path filePath;
    protected FSDataInputStream hfile;
    protected FileStatus fileStatus;

    public HDFSRandomAccessFile(String fileSystemURI, String location) throws IOException {
        this(fileSystemURI, location, defaultBufferSize);
    }

    public HDFSRandomAccessFile(String fileSystemURI, String location, int bufferSize) throws IOException {
        super(bufferSize);
        fsURI = URI.create(fileSystemURI);
        filePath = new Path(location);
        this.location = location;
        if (debugLeaks) {
            openFiles.add(location);
        }

        FileSystem fs = FileSystem.get(fsURI, new Configuration());
        hfile = fs.open(filePath);

        fileStatus = fs.getFileStatus(filePath);
    }

    @Override
    public void flush() {

    }

    @Override
    public synchronized void close() throws IOException {
        super.close();
        hfile.close();
    }

    public long getLastModified() {
        return fileStatus.getModificationTime();
    }

    @Override
    public long length() throws IOException {
        return fileStatus.getLen();
    }

    @Override
    protected int read_(long pos, byte[] b, int offset, int len) throws IOException {
        int n = hfile.read(pos, b, offset, len);
        return n;
    }

    @Override
    public long readToByteChannel(WritableByteChannel dest, long offset, long nbytes) throws IOException {
        long need = nbytes;
        byte[] buf = new byte[4096];

        hfile.seek(offset);
        int count = 0;
        while (need > 0 && count != -1) {
            need -= count;
            dest.write(ByteBuffer.wrap(buf, 0, count));
            count = hfile.read(buf, 0, 4096);
        }
        return nbytes - need;
    }
}