Hex.java

package hamaster.gradesign.ibe.util;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.List;

/**
 * 十六进制编码工具类
 * @author <a href="mailto:wangyeee@gmail.com">王烨</a>
 */
public final class Hex {

	private Hex() {
	}

	/**
	 * 使用十六进制编码数据
	 * @param data 要编码的数据
	 * @return 编码后的字符串
	 */
	public final static String hex(byte[] data) {
		return hex(data, 0, data.length);
	}

	/**
	 * 使用十六进制编码数据
	 * @param data 要编码的数据
	 * @param offset 其实偏移 0开始
	 * @param count 编码字节的数量
	 * @return 编码后的字符串
	 */
	public final static String hex(byte[] data, int offset, int count) {
		if (offset < 0)
			throw new IllegalArgumentException(new StringBuilder("invalid offset:").append(offset).toString());
        if (count < 0)
        	throw new IllegalArgumentException(new StringBuilder("invalid count:").append(offset).toString());
        if (offset > data.length - count)
            throw new ArrayIndexOutOfBoundsException(offset + count);
		ByteArrayOutputStream out = new ByteArrayOutputStream(data.length + data.length);
		PrintStream writer = new PrintStream(out);
		for (int i = offset; i < offset + count; i++) {
			writer.printf("%02x", data[i]);
		}
		return out.toString();
	}

	/**
	 * 将十六进制编码的数据还原
	 * @param hex 要还原的字符串
	 * @return 还原后的数据
	 * @throws NumberFormatException 字符串中包含无法格式化为数字的字符
	 */
	public final static byte[] unhex(String hex) {
		char[] tb = hex.toUpperCase().toCharArray();
		List<Byte> bs = new ArrayList<Byte>();
		for (int i = 0; i < tb.length; i += 2) {
			String t = new String();
			t += tb[i];
			t += tb[i + 1];
			int safe = Integer.parseInt(t, 16);
			if (safe > 127)
				safe -= 256;
			bs.add(Byte.parseByte(String.valueOf(safe)));
		}
		byte[] raw = new byte[bs.size()];
		for (int i = 0; i < bs.size(); i++)
			raw[i] = bs.get(i);
		return raw;
	}

	/**
	 * 将64位的long转换成8个字节的数组
	 * @param l 要转换的long
	 * @return 转换后的数组
	 */
	public final static byte[] longToBytes(long l) {
		byte[] buffer = new byte[8];
		buffer[0] = (byte) (0xff & (l >> 56));
		buffer[1] = (byte) (0xff & (l >> 48));
		buffer[2] = (byte) (0xff & (l >> 40));
		buffer[3] = (byte) (0xff & (l >> 32));
		buffer[4] = (byte) (0xff & (l >> 24));
		buffer[5] = (byte) (0xff & (l >> 16));
		buffer[6] = (byte) (0xff & (l >> 8));
		buffer[7] = (byte) (0xff & l);
		return buffer;
	}

	/**
	 * 将8个字节组装成一个long
	 * @param bytes 要转换的字节数组
	 * @return 组装后的long
	 */
	public final static long bytesToLong(byte[] bytes) {
		return bytesToLong(bytes, 0);
	}

	/**
	 * 将8个字节组装成一个long
	 * @param bytes 要转换的字节数组
	 * @param offset 数组中开始读取的偏移量
	 * @return 组装后的long
	 */
	public final static long bytesToLong(byte[] bytes, int offset) {
		if (bytes == null || offset + 8 > bytes.length)
			throw new IllegalArgumentException("invalid byte array to convert!");
		return (((long) (bytes[0 + offset] & 0xff) << 56) |
				((long) (bytes[1 + offset] & 0xff) << 48) |
				((long) (bytes[2 + offset] & 0xff) << 40) |
				((long) (bytes[3 + offset] & 0xff) << 32) |
				((long) (bytes[4 + offset] & 0xff) << 24) |
				((long) (bytes[5 + offset] & 0xff) << 16) |
				((long) (bytes[6 + offset] & 0xff) <<  8) |
				((long) (bytes[7 + offset] & 0xff)));
	}

	/**
	 * 将32bit的int转换为字节数组
	 * @param i 要转换的int
	 * @return 转换完成的数组 长度4字节
	 */
	public final static byte[] intToByte(int i) {
		byte[] bt = new byte[4];
		bt[0] = (byte) ((0xff000000 & i) >> 24);
		bt[1] = (byte) ((0xff0000 & i) >> 16);
		bt[2] = (byte) ((0xff00 & i) >> 8);
		bt[3] = (byte) (0xff & i);
		return bt;
	}

	/**
	 * 将4字节的数组转换成int
	 * @param bytes 要转换的字节数组
	 * @return 转换后的int
	 */
	public final static int bytesToInt(byte[] bytes) {
		return bytesToInt(bytes ,0);
	}

	/**
	 * 将数组中的部分数据转换为int
	 * @param bytes 要转换的数组
	 * @param offset 起始偏移量 从0开始
	 * @return 读取4个字节的内容 将它们转换为32bit的int并返回
	 */
	public final static int bytesToInt(byte[] bytes, int offset) {
		if (bytes == null || offset + 4 > bytes.length)
			throw new IllegalArgumentException("invalid byte array to convert!");
		return (((bytes[0 + offset] & 0xff) << 24) |
				((bytes[1 + offset] & 0xff) << 16) |
				((bytes[2 + offset] & 0xff) <<  8) |
				 (bytes[3 + offset] & 0xff));
	}
}