问连接到Google日历时出错

EN

public GoogleCredential conexion(String email, String scope) { 

    GoogleCredential credential =null;
    try{

        // Build service account credential.
        credential = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT)
        .setJsonFactory(JSON_FACTORY)
        .setServiceAccountId(SERVICE_ACCOUNT_EMAIL)
        .setServiceAccountScopes(scope)
        .setServiceAccountPrivateKeyFromP12File(new File(file))
        .setServiceAccountUser(email)
        .build();
    }
    catch(Exception e){
        e.printStackTrace();

    }


return credential;

}


public int function(){
    GoogleCredential sa = serviceAc.conexion("user@mail.com",CalendarScopes.CALENDAR);

    Calendar service = new Calendar(new NetHttpTransport(), new JacksonFactory(), sa);//   here throw the exception
.
.
.
}