Here you can find the source of readFile(String file)
public static byte[] readFile(String file) throws IOException
//package com.java2s; //License from project: Open Source License import java.io.File; import java.io.IOException; import java.io.RandomAccessFile; public class Main { public static byte[] readFile(String file) throws IOException { return readFile(new File(file)); }//from w w w. j a v a 2 s . co m public static byte[] readFile(File file) throws IOException { // Open file RandomAccessFile f = new RandomAccessFile(file, "r"); try { // Get and check length long longlength = f.length(); int length = (int) longlength; if (length != longlength) throw new IOException("File size >= 2 GB"); // Read file and return data byte[] data = new byte[length]; f.readFully(data); return data; } finally { f.close(); } } }