把一个文件转化成byte[] 数组

啥都不说了，给一个文件，返回给byte数组

// read the photo file into a byte array...
	public static byte[] getBytesFromFile(File file) throws IOException {
		InputStream is = new FileInputStream(file);
		// Get the size of the file
		long length = file.length();
		// You cannot create an array using a long type.
		// It needs to be an int type.
		// Before converting to an int type, check
		// to ensure that file is not larger than Integer.MAX_VALUE.
		if (length > Integer.MAX_VALUE) {
			// File is too large
		}
		// Create the byte array to hold the data
		byte[] bytes = new byte[(int) length];
		// Read in the bytes
		int offset = 0;
		int numRead = 0;
		while (offset < bytes.length
				&& (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
			offset += numRead;
		}
		// Ensure all the bytes have been read in
		if (offset < bytes.length) {
			throw new IOException("Could not completely read file "
					+ file.getName());
		}
		// Close the input stream and return bytes
		is.close();
		return bytes;
	}