java字节、字符串互相转换类

可用于把文件转换成字符串，存储到源文件的String变量中。

package demo;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class TransformUtil {
	/*
	 * Convert byte[] to hex
	 * string.这里我们可以将byte转换成int，然后利用Integer.toHexString(int)来转换成16进制字符串。
	 * 
	 * @param src byte[] data
	 * 
	 * @return hex string
	 */
	public static String bytesToHexString(byte[] src) {
		StringBuilder stringBuilder = new StringBuilder("");
		if (src == null || src.length <= 0) {
			return null;
		}
		for (int i = 0; i < src.length; i++) {
			int v = src[i] & 0xFF;
			String hv = Integer.toHexString(v);
			if (hv.length() < 2) {
				stringBuilder.append(0);
			}
			stringBuilder.append(hv);
		}
		return stringBuilder.toString();
	}

	/**
	 * Convert hex string to byte[]
	 * 
	 * @param hexString
	 *            the hex string
	 * @return byte[]
	 */
	public static byte[] hexStringToBytes(String hexString) {
		if (hexString == null || hexString.equals("")) {
			return null;
		}
		hexString = hexString.toUpperCase();
		int length = hexString.length() / 2;
		char[] hexChars = hexString.toCharArray();
		byte[] d = new byte[length];
		for (int i = 0; i < length; i++) {
			int pos = i * 2;
			d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
		}
		return d;
	}

	/**
	 * Convert char to byte
	 * 
	 * @param c
	 *            char
	 * @return byte
	 */
	private static byte charToByte(char c) {
		return (byte) "0123456789ABCDEF".indexOf(c);
	}

	public static void main(String[] args) throws IOException {
		File file = new File("e:\\consola.ttf");
		System.out.println(file.length());
		ByteBuffer bb = ByteBuffer.allocateDirect(1024);
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		FileChannel fc = new FileInputStream(file).getChannel();
		
		for (;fc.read(bb) > 0;) {
			bb.flip();
			for(;bb.hasRemaining();){
				baos.write(bb.get());
			}
			bb.clear();
		}
		System.out.println(bytesToHexString(baos.toByteArray()).trim());
	}
}