Java File Read via ByteBuffer readFile(String filename)

Description

read File

License

Open Source License

Declaration

public static String readFile(String filename) 

Method Source Code

//package com.java2s;
/*/* www .ja  v a 2  s  . c  om*/
 *  Copyright (c) 2009, Amostudio,inc
 *  All rights reserved.
 *  Code licensed under the BSD License:
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *        documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Amostudio,inc  nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY Amostudio,inc ''AS IS'' AND ANY
 *   EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 *   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *   DISCLAIMED. IN NO EVENT SHALL Amostudio,inc  BE LIABLE FOR ANY
 *   DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 *  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

import java.io.IOException;

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

public class Main {
    public static String readFile(String filename) {
        return readFile(filename, false);
    }

    public static String readFile(String filename, boolean useNIO) {
        String s = "";
        if (useNIO) {
            s = new String(largeFileReader(filename));
        } else {
            s = new String(smallFileReader(filename));
        }
        return s;
    }

    /**
     *
     * good for Large Files >2Mb
     * @param filename
     * @return
     */
    private static byte[] largeFileReader(String filename) {
        byte[] bytes = null;
        FileChannel fc = null;
        try {
            fc = new FileInputStream(filename).getChannel();

            MappedByteBuffer byteBuffer = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
            int size = byteBuffer.capacity();
            if (size > 0) {
                // Retrieve all bytes in the buffer
                byteBuffer.clear();
                bytes = new byte[size];
                byteBuffer.get(bytes, 0, bytes.length);
            }
            fc.close();
        } catch (FileNotFoundException fnf) {
            System.err.println("" + fnf);
        } catch (IOException io) {
            System.err.println("" + io);
        } finally {
            if (fc != null) {
                try {
                    fc.close();
                } catch (IOException ioe) {
                    // ignore
                }
            }
        }
        return bytes;
    }

    public static byte[] smallFileReader(String filename) {
        byte[] buffer = null;
        FileInputStream in = null;
        try {
            File file = new File(filename);
            int size = (int) file.length();
            if (size > 0) {
                buffer = new byte[size];
                in = new FileInputStream(file);
                in.read(buffer, 0, size);

                //s = new String(buffer, 0, size);
                in.close();
            }
        } catch (FileNotFoundException fnfx) {
            System.err.println("File not found: " + fnfx);
        } catch (IOException iox) {
            System.err.println("I/O problems: " + iox);
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException ioe) {
                }
            }
        }
        return buffer;
    }
}

Related

1. readFile(File file)
2. readFile(java.io.File file)
3. readFile(String filename)
4. readFile(String filename)
5. readFile(String fileName)
6. readFile(String filePath)
7. readFile(String name)
8. readFile(String name)
9. readFile(String path)