使用OpenSSL命令手动计算公钥的哈希值，并截取前32个字节作为Android SSL Pinning所需的哈希值。

示例代码：

1. 使用openssl命令生成.pem格式的公钥文件并计算SHA256哈希值：

openssl x509 -in cert.crt -pubkey -noout > pub.pem
openssl rsa -in pub.pem -pubin -outform der | openssl dgst -sha256 -binary | xxd -p

2. 在Android应用程序中，使用如下代码获取证书的SHA256哈希值：

public static String getCertificateSHA256Fingerprint(Context context) throws PackageManager.NameNotFoundException, NoSuchAlgorithmException {
    PackageManager pm = context.getPackageManager();
    String packageName = context.getPackageName();
    int flags = PackageManager.GET_SIGNATURES;
    PackageInfo packageInfo = pm.getPackageInfo(packageName, flags);
    Signature[] signatures = packageInfo.signatures;
    byte[] cert = signatures[0].toByteArray();

    MessageDigest digest = MessageDigest.getInstance("SHA256");
    byte[] hash = digest.digest(cert);

    return bytesToHex(hash);
}

private static String bytesToHex(byte[] hash) {
    StringBuilder hexString = new StringBuilder();
    for (byte b : hash) {
        String hex = Integer.toHexString(0xFF & b);
        if (hex.length() == 1) {
            hexString.append('0');
        }
        hexString.append(hex);
    }
    return hexString.toString();
}