import org.bouncycastle.asn1.pkcs.RSAPrivateKeyStructure; //导入依赖的package包/类
/**
 * 加载 PKCS#1 编码的 pem 格式私钥
 * 
 * @param privateKeyStr 私钥
 * @throws Exception
 */
public void loadPrivateKeyPEMPKCS1(String privateKeyStr) throws Exception {
    try {
        byte[] e = Base64.decode(privateKeyStr);
        // 读取 PKCS#1的私钥
        RSAPrivateKeyStructure asn1PrivateKey = new RSAPrivateKeyStructure(
                                                                           (ASN1Sequence) ASN1Sequence.fromByteArray(e));
        RSAPrivateKeySpec rsaPrivateKeySpec = new RSAPrivateKeySpec(asn1PrivateKey.getModulus(),
                                                                    asn1PrivateKey.getPrivateExponent());
        // 实例化KeyFactory对象，并指定 RSA 算法
        KeyFactory keyFactory = KeyFactory.getInstance(SIGN_ALGORITHMS);
        // 获得 PrivateKey 对象
        this.privateKey = keyFactory.generatePrivate(rsaPrivateKeySpec);
    } catch (NoSuchAlgorithmException var6) {
        throw new Exception("无此算法");
    } catch (InvalidKeySpecException var7) {
        throw new Exception("私钥非法");
    } catch (IOException var8) {
        throw new Exception("私钥数据内容读取错误");
    } catch (NullPointerException var9) {
        throw new Exception("私钥数据为空");
    }
}