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Marcin Parśniak
Marcin Parśniak

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Finovara - Building a Simple Chatbot in Spring Boot

#java #ai #opensource #programming

Recently, I added a simple chatbot to my Finovara app that answers users’ finance-related questions.

No AI, no NLP libraries — just clean architecture, enums, and text files.

It works surprisingly well for the limited scope we need. Here’s how it’s built.

The Idea

The chatbot works like this:

  1. A user asks a question.
  2. The system normalizes the input.
  3. It maps the question to a predefined entry.
  4. The entry corresponds to a SmartReportType enum.
  5. The enum is handled by a handler class.
  6. The handler generates the actual response.

This makes the system:

  • Predictable
  • Easy to extend
  • Fast and lightweight

Core Architecture

The main entry point is:

  public String generateResponse(String email, String userQuestion) {
        User user = userManagerService.getUserByEmailOrThrow(email);

        SmartReportType type = smartReportQuestionService.getTypeFromQuestion(userQuestion);

        if (type == null)
            return "I’m not smart enough to answer this question. Please ask a question from the question book!";

        SmartReportHandler handler = handlers.get(type);

        if (handler == null) {
            return "Report type not supported";
        }

        return handler.generate(user.getId());
    }
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Here’s what’s happening:

The question is mapped to a SmartReportType enum.
Each enum has its own handler.
The handler generates a response based on templates and user data.

This is basically a Strategy Pattern in action.

Mapping Questions to Enums

Instead of hardcoding questions in Java, they are stored in TXT files:

MONTH_SPENDING | how much did i spend this month
MONTH_SPENDING | monthly expenses
AVERAGE_DAY_SPENDING | average daily spending
EXPENSE_RATE | what percentage of my income is spent
SAVINGS_RATE | how much did i save
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Loader Service: 

questionMap.put(question, SmartReportType.valueOf(enumName));
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Normalization: 

private String normalize(String text) {
    return text.toLowerCase()
        .trim()
        .replace("?", "");
}
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Thanks to this:

  • “How much did I spend?”
  • “how much did i spend”
  • “HOW MUCH DID I SPEND??”

all map to the same key.

Handlers: Business Logic

Each enum type has its own handler:

public interface SmartReportHandler {
    SmartReportType getType();
    String generate(Long userId);
}
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Handlers are responsible for fetching user data and generating responses.

Example: Expense Rate 

BigDecimal total = sumExpenses.multiply(BigDecimal.valueOf(100))
    .divide(sumRevenue, 2, RoundingMode.HALF_UP);

String template = templateService.getRandomResponse(SmartReportType.EXPENSE_RATE);
return template.replace("{amount}", total.toString());
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Dynamic Responses (Templates)

Responses are stored in text files instead of being hardcoded:

You spent {amount} this month.
Your total expenses are {amount}.
Your savings rate is {amount}%.
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Randomization makes replies feel less repetitive:

return responses.get(random.nextInt(responses.size()));
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*Thanks for reading! *

If you’re curious to see the full project or try it yourself, check out the code on GitHub:

GitHub logo M4rc1nek / finovara-backend

Backend service for a personal finance management application

Finovara

Backend platform for a personal finance management application, built with Java 25 and Spring Boot 4 as a set of microservices.

About the Project

Finovara is a personal finance platform designed to help users take full control of their money. The backend exposes a secure REST API that powers tracking of income and expenses, budget management, savings goals, shared accounts and financial reporting.

The platform is built as a set of independent services, each responsible for a separate area of the domain, so that individual parts of the system can be developed, deployed and scaled on their own. Security is a central concern: authentication is based on JWT, sessions are tracked per device, and user activity is recorded in an audit log.

Key Features

Accounts and Security

  • Authentication and Authorization - stateless JWT security built on Spring Security, with an access and refresh token flow.
  • Device and Session Tracking…


View on GitHub


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