android 类型转换工具函数

android中类型转换好像支持不是太好，备份下有用的类型转换函数和工具函数.

一、类型转换

1.byte 转 int ( int 可以再转成long double float ）

[java]
public static int byteToInt(byte[] data, int offset)
{
        int result = 0;
    int n1, n2, n3, n4;

    n1 = data[offset + 3] & 0xFF;
    n2 = data[offset + 2] & 0xFF;
    n3 = data[offset + 1] & 0xFF;
    n4 = data[offset] & 0xFF;

    result = n1 << 24 | n2 << 16 | n3 << 8 | n4;

    return result;
}

2. byte 转 Hex
[java] www.zzzyk.com
public static String toHexString(byte[] b)
{
    char HEX_DIGITS[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                  'A', 'B', 'C', 'D', 'E', 'F' };

        StringBuilder sb = new StringBuilder(b.length * 2);
        for (int i = 0; i < b.length; i++)
        {
            sb.append(HEX_DIGITS[(b[i] & 0xf0) >> 4]);
            sb.append(HEX_DIGITS[b[i] & 0x0f]);
        }
        return sb.toString();
}

3. HexString 转 long

[java]
public static long hexStringToLong(String s)
{
    String serial = "0123456789ABCDEF";

    s = s.trim().toUpperCase();
    if( s.length() > 8 ) return 0;

    long num = 0;
    int len = s.length();

    for( int i = 0; i < len; i++)
    {
        num += (serial.indexOf( s.charAt(i) ) << (4 * (len - i - 1)));
    }

    return num;
}

二、工具函数
1. md5sum

[java]
public static String getMd5sum(String filename)
{
        InputStream fis;
        byte[] buffer = new byte[1024];
        int numRead = 0;
        MessageDigest md5;
        try{
            fis = new FileInputStream(filename);
            md5 = MessageDigest.getInstance("MD5");
            while((numRead=fis.read(buffer)) > 0) {
                md5.update(buffer,0,numRead);
            }
            fis.close();
            return toHexString(md5.digest());
        } catch (Exception e) {
            return null;
        }
}

补充：移动开发 , Android ,

android 类型转换 工具函数

android 类型转换工具函数