获取Andorid apk 签名方式

public static byte[] getSignature(Context context) {
    try {
        String pkgname = context.getPackageName();
        PackageManager manager = context.getPackageManager();
        PackageInfo packageInfo = manager.getPackageInfo(pkgname, PackageManager.GET_SIGNATURES);
        Signature[] signatures = packageInfo.signatures;
        return signatures[0].toByteArray();
    } catch (Exception e) {
        return null;
    }
}

public static String md5(byte[] bytes) {
    try {
        MessageDigest md = MessageDigest.getInstance("MD5");
        md.update(bytes);
        byte[] b = md.digest();
        int i;
        StringBuilder sb = new StringBuilder();
        for (byte value : b) {
            i = value;
            if (i < 0)
                i += 256;
            if (i < 16)
                sb.append("0");
            sb.append(Integer.toHexString(i));
        }
        return sb.toString();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return "";
}