Java RandomAccessFile Read readFileBytes(final File file)

Description

Reads the bytes from the given file if it is a file and it exists.

License

Open Source License

Parameter

Parameter	Description
file	the file object

Return

a byte array

Declaration

public static byte[] readFileBytes(final File file) 

Method Source Code

//package com.java2s;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Main {
    /**//from w  w  w . j a  v a2 s.co  m
     * Reads an array of bytes from the given input stream.
     * @param inputstream the input stream
     * @return the bytes or null if the inputstream is null
     */
    public static byte[] readFileBytes(final InputStream inputstream) {
        if (inputstream == null)
            return null;

        // Start with a buffer size between 1K and 1M based on available memory.
        final int minBufferSize = (int) Math.max(1024,
                Math.min(Runtime.getRuntime().freeMemory() / 10, 1024 * 1024));

        List buffers = new ArrayList();
        int totalBytesRead = 0;

        // Fill buffer lists
        try {
            byte[] curBuf = new byte[minBufferSize];
            int curBufPos = 0;

            int bytesRead;
            while ((bytesRead = inputstream.read(curBuf, curBufPos, curBuf.length - curBufPos)) != -1) {
                totalBytesRead += bytesRead;
                curBufPos += bytesRead;

                if (curBufPos == curBuf.length) {
                    buffers.add(curBuf);
                    curBuf = new byte[minBufferSize];
                    curBufPos = 0;
                }
            }
            buffers.add(curBuf);
        } catch (IOException ex) {
            //      LOG.throwing("FileUtils", "readFileBytes", ex);
            throw new RuntimeException("Unable to read file bytes", ex);
        }

        byte[] result = new byte[totalBytesRead];
        int pos = 0;
        Iterator it = buffers.iterator();
        while (it.hasNext()) {
            byte[] curBuf = (byte[]) it.next();
            int copy = curBuf.length;
            if (copy > (totalBytesRead - pos))
                copy = totalBytesRead - pos;
            System.arraycopy(curBuf, 0, result, pos, copy);
            pos += copy;
        }

        return result;
    }

    /**
     * Reads the bytes from the given file if it is a file and it exists.
     * @param file the file object
     * @return a byte array
     */
    public static byte[] readFileBytes(final File file) {
        byte[] data = null;
        if (file != null && file.exists() && file.isFile()) {
            RandomAccessFile raf = null;
            try {
                raf = new RandomAccessFile(file, "r");
                data = new byte[(int) raf.length()];
                raf.readFully(data);
            } catch (IOException ex) {
                ex.printStackTrace();
            } finally {
                if (raf != null) {
                    try {
                        raf.close();
                    } catch (Exception ex) {
                        //            LOG.throwing("FileUtils", "readFileBytes", ex);
                    }
                }
            }
        }
        return data;
    }
}

Related

1. readFile(String file)
2. readFile(String file)
3. readFile(String filename)
4. readFile(String filePath)
5. readFileByRandomAccess(String fileName)
6. readFileFully(File f)
7. readLine(RandomAccessFile file, long position, int trim)
8. readLongLittleEndian( RandomAccessFile randomAccessFile)