Data Model Configruation

Define the entity representing a financial account within the system.

package com.example.financial.model;

import java.io.Serializable;

public class BankAccount implements Serializable {
    private Long accountId;
    private String accountHolder;
    private Double availableBalance;

    public BankAccount() {
    }

    public BankAccount(Long accountId, String accountHolder, Double availableBalance) {
        this.accountId = accountId;
        this.accountHolder = accountHolder;
        this.availableBalance = availableBalance;
    }

    // Getters and Setters
    public Long getAccountId() {
        return accountId;
    }

    public void setAccountId(Long accountId) {
        this.accountId = accountId;
    }

    public String getAccountHolder() {
        return accountHolder;
    }

    public void setAccountHolder(String accountHolder) {
        this.accountHolder = accountHolder;
    }

    public Double getAvailableBalance() {
        return availableBalance;
    }

    public void setAvailableBalance(Double availableBalance) {
        this.availableBalance = availableBalance;
    }
}

Data Access Layer (DAO)

Create an interface to hendle balence modifications via JDBC.

package com.example.financial.dao;

public interface AccountRepository {
    int updateAccountBalance(Long accountId, Double amount);
}

Implement the repository using JdbcTemplate to execute the SQL update.

package com.example.financial.dao.impl;

import com.example.financial.dao.AccountRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

@Repository
public class JdbcAccountRepository implements AccountRepository {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public int updateAccountBalance(Long accountId, Double amount) {
        String sqlStatement = "UPDATE bank_accounts SET available_balance = available_balance + ? WHERE account_id = ?";
        return jdbcTemplate.update(sqlStatement, amount, accountId);
    }
}

Business Service Layer

Define the service contract for transferring funds between accounts.

package com.example.financial.service;

public interface TransferService {
    boolean executeTransfer(Long sourceId, Long targetId, Double amount);
}

Implement the business logic to handle the debit and credit operations.

package com.example.financial.service.impl;

import com.example.financial.dao.AccountRepository;
import com.example.financial.service.TransferService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MoneyTransferService implements TransferService {

    @Autowired
    private AccountRepository accountRepository;

    @Override
    public boolean executeTransfer(Long sourceId, Long targetId, Double amount) {
        // Debit the source account
        int debitResult = accountRepository.updateAccountBalance(sourceId, -amount);

        // Credit the target account
        int creditResult = accountRepository.updateAccountBalance(targetId, amount);

        return debitResult > 0 && creditResult > 0;
    }
}

Integration Testing

Verify the functionality by initializing the Spring context and invoking the transfer method.

package com.example.financial.test;

import com.example.financial.service.TransferService;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TransactionTestSuite {

    @Test
    public void testTransferExecution() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        TransferService transferService = context.getBean(TransferService.class);

        boolean status = transferService.executeTransfer(1L, 2L, 500.0);
        System.out.println("Operation Status: " + status);
    }
}