根据pfx文件创建PrivateKey对象

public static PrivateKey getPrivateKeyByPfx(String pfxPath, String password) throws Exception {
   File pfxFile = new File(pfxPath);
   return getPrivateKeyByPfx(FileUtils.readFileToByteArray(pfxFile), password);
}
public static PrivateKey getPrivateKeyByPfx(byte[] pfxData, String password) throws Exception {
   PrivateKey privateKey = null;
   KeyStore keystore = getKeyStore(pfxData, password);
   Enumeration<String> enums = keystore.aliases();
   String keyAlias = "";
   while (enums.hasMoreElements()) {
      keyAlias = enums.nextElement();
      if (keystore.isKeyEntry(keyAlias)) {
         privateKey = (PrivateKey) keystore.getKey(keyAlias, password.toCharArray());
      }
   }
   return privateKey;
}
private static KeyStore getKeyStore(byte[] pfxData, String password) throws Exception {
   KeyStore keystore = KeyStore.getInstance("PKCS12");
   keystore.load(new ByteArrayInputStream(pfxData), password.toCharArray());
   return keystore;
}