Login using HttpClient school educational administration system, the verification code is a simple four-digit captcha images, with OCR automatically fill in, the login user name and password are correct, cookie every request brought, HttpClient object is the same, but each time to return a json, display verification code is not correct, the authentication code with Commons - IO images saved to the local, and OCR return is the same, confirm the verification code are all right, so where is the problem? The bosses of bosses, answer, have to understand I can provide detailed code