数字类型转换

在对APDU进行十进制、十六进制、字节、字符串转换时用到下列方法：

package com.example.android.BluetoothChat;

public class Convertor {

    /* 给APDU添加前缀和后缀 */
    public static String m_encode_apdu(String apdu)
    {
        int len = apdu.length() / 2;
        String lenHex = m_convert_int_to_hex_string(len);
        return "02" + "00" + lenHex + "80" + "FFFFFFFF" +
            apdu + "01" + "03";
    }
    
    /* 十进制数值转换为十六进制字符串 */
    public static String m_convert_int_to_hex_string(int d){
    	String hex = Integer.toHexString(d);
    	if (hex.length() == 1) {   
            hex = '0' + hex;   
        }
    	return hex.toUpperCase();
    }
    
    /* 字节数值转换为十六进制字符串 */
    public static String m_convert_byte_to_hex_string(byte b){
    	String hex = Integer.toHexString(b & 0xFF);   
        if (hex.length() == 1) {   
            hex = '0' + hex;   
        }
        return hex.toUpperCase();
    }
    
    /* 字节数组转换为十六进制字符串 */
	public static String m_convert_byte_array_to_hex_string(byte[] ba) {
		String hex = "";
		for (int i = 0; i < ba.length; i++) {
			hex += m_convert_byte_to_hex_string(ba[i]);
		}
		return hex;
	}
    
    /* 整形数值转换为长度为4的字节数组 */
    public static byte[] m_convert_int_to_byte_array(int d)
    {
        byte[] ba = new byte[4];
        for (int i = 0; i < 4; i++)
        {
            ba[i] = (byte)(d >> 8 * (3 - i) & 0xFF);
        }
        return ba;
    }
    
    /* 整形数值转换为十六进制字符串 */
    public static String m_convert_int_to_byte_hex_String(int d){
    	byte[] ba = m_convert_int_to_byte_array(d);
    	String hexString = m_convert_byte_array_to_hex_string(ba);
    	return hexString;
    }
}