廢話不多說，請看：

    /**  
     * 字串轉換成十六進位制字串 
     * @param String str 待轉換的ASCII字串 
     * @return String 每個Byte之間空格分隔，如: [61 6C 6B] 
     */    
    public static String str2HexStr(String str)  
    {    
  
        char[] chars = "0123456789ABCDEF".toCharArray();    
        StringBuilder sb = new StringBuilder("");  
        byte[] bs = str.getBytes();    
        int bit;    
          
        for (int i = 0; i < bs.length; i++)  
        {    
            bit = (bs[i] & 0x0f0) >> 4;    
            sb.append(chars[bit]);    
            bit = bs[i] & 0x0f;    
            sb.append(chars[bit]);  
            sb.append(' ');  
        }    
        return sb.toString().trim();    
    }  
      
    /**  
     * 十六進位制轉換字串 
     * @param String str Byte字串(Byte之間無分隔符 如:[616C6B]) 
     * @return String 對應的字串 
     */    
    public static String hexStr2Str(String hexStr)  
    {    
        String str = "0123456789ABCDEF";    
        char[] hexs = hexStr.toCharArray();    
        byte[] bytes = new byte[hexStr.length() / 2];    
        int n;    
  
        for (int i = 0; i < bytes.length; i++)  
        {    
            n = str.indexOf(hexs[2 * i]) * 16;    
            n += str.indexOf(hexs[2 * i + 1]);    
            bytes[i] = (byte) (n & 0xff);    
        }    
        return new String(bytes);    
    }  
      
    /** 
     * bytes轉換成十六進位制字串 
     * @param byte[] b byte陣列 
     * @return String 每個Byte值之間空格分隔 
     */  
    public static String byte2HexStr(byte[] b)  
    {  
        String stmp="";  
        StringBuilder sb = new StringBuilder("");  
        for (int n=0;n<b.length;n++)  
        {  
            stmp = Integer.toHexString(b[n] & 0xFF);  
            sb.append((stmp.length()==1)? "0"+stmp : stmp);  
            sb.append(" ");  
        }  
        return sb.toString().toUpperCase().trim();  
    }  
      
    /** 
     * bytes字串轉換為Byte值 
     * @param String src Byte字串，每個Byte之間沒有分隔符 
     * @return byte[] 
     */  
    public static byte[] hexStr2Bytes(String src)  
    {  
        int m=0,n=0;  
        int l=src.length()/2;  
        System.out.println(l);  
        byte[] ret = new byte[l];  
        for (int i = 0; i < l; i++)  
        {  
            m=i*2+1;  
            n=m+1;  
            ret[i] = Byte.decode("0x" + src.substring(i*2, m) + src.substring(m,n));  
        }  
        return ret;  
    }  
  
    /** 
     * String的字串轉換成unicode的String 
     * @param String strText 全形字串 
     * @return String 每個unicode之間無分隔符 
     * @throws Exception 
     */  
    public static String strToUnicode(String strText)  
        throws Exception  
    {  
        char c;  
        StringBuilder str = new StringBuilder();  
        int intAsc;  
        String strHex;  
        for (int i = 0; i < strText.length(); i++)  
        {  
            c = strText.charAt(i);  
            intAsc = (int) c;  
            strHex = Integer.toHexString(intAsc);  
            if (intAsc > 128)  
                str.append("\\u" + strHex);  
            else // 低位在前面補00  
                str.append("\\u00" + strHex);  
        }  
        return str.toString();  
    }  
      
    /** 
     * unicode的String轉換成String的字串 
     * @param String hex 16進位制值字串 （一個unicode為2byte） 
     * @return String 全形字串 
     */  
    public static String unicodeToString(String hex)  
    {  
        int t = hex.length() / 6;  
        StringBuilder str = new StringBuilder();  
        for (int i = 0; i < t; i++)  
        {  
            String s = hex.substring(i * 6, (i + 1) * 6);  
            // 高位需要補上00再轉  
            String s1 = s.substring(2, 4) + "00";  
            // 低位直接轉  
            String s2 = s.substring(4);  
            // 將16進位制的string轉為int  
            int n = Integer.valueOf(s1, 16) + Integer.valueOf(s2, 16);  
            // 將int轉換為字元  
            char[] chars = Character.toChars(n);  
            str.append(new String(chars));  
        }  
        return str.toString();  
    }