Java File Write via ByteBuffer mmap(File file, long offset, long length, boolean writeable)

Description

mmap

License

Apache License

Declaration

public static MappedByteBuffer mmap(File file, long offset, long length, boolean writeable) throws IOException 

Method Source Code

//package com.java2s;
/*//from w  w  w .j  ava2 s .c  o m
 * Copyright 2012 Johns Hopkins University
 *
 * Licensed 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 java.io.File;
import java.io.IOException;

import java.io.RandomAccessFile;

import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

public class Main {
    public static MappedByteBuffer mmap(File file, long offset, long length, boolean writeable) throws IOException {
        FileChannel chan = channel(file, writeable);
        FileChannel.MapMode mode = writeable ? FileChannel.MapMode.READ_WRITE : FileChannel.MapMode.READ_ONLY;
        MappedByteBuffer buf = chan.map(mode, offset, length);
        chan.close();

        return buf;
    }

    public static FileChannel channel(File file, boolean writeable) throws IOException {
        String opts = writeable ? "rw" : "r";
        RandomAccessFile fd = new RandomAccessFile(file, opts);
        FileChannel chan = fd.getChannel();

        return chan;
    }
}

Related

1. newWriteableBuffer(int capacity)
2. write(File file, String content, String encoding)
3. write(InputStream source, File target)
4. write(Path file, String content)