"创建一个 jdbc 连接对象但连接太多"

Question

我刚刚创建了一个 JDBC 连接对象，在将数据插入数据库时​​出现了太多的连接错误。 我试图在不同的线程中找到原因，但据我所知，“连接太多”错误是由于没有关闭旧连接并创建新连接造成的。

public class LoadToDB {
    Connection conn;

    public LoadToDB(String url, String user, String password) {
        try {
            conn = DriverManager.getConnection(url, user, password);
            conn.setAutoCommit(true);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

static final String insertCustomer = "INSERT INTO bank_customer (" +
            "CUSTOMER_ID, " +
            "CUSTOMER_NAME, " +
            "CUSTOMER_SURNAME, " +
            "CUSTOMER_ADDRESS, " +
            "CUSTOMER_ZIP_CODE, " +
            "CUSTOMER_NATIONAL_ID, " +
            "CUSTOMER_BIRTH_DATE ) " +
            "values (?, ?, ?, ?, ?, ?, ?)";


public boolean insertCustomer(List<Customer> customerList) throws SQLException {
        int row = 0;
        for (Customer customer : customerList) {
            try {
                PreparedStatement insertCustomerStatement = conn.prepareStatement(insertCustomer);
                insertCustomerStatement.setString(1, String.valueOf(customer.getCustomerID()));
                insertCustomerStatement.setString(2, customer.getCustomerName());
                insertCustomerStatement.setString(3, customer.getCustomerSurname());
                insertCustomerStatement.setString(4, customer.getCustomerAddress());
                insertCustomerStatement.setString(5, customer.getCustomerZipCode());
                insertCustomerStatement.setString(6, String.valueOf(customer.getCustomerNationalID()));
                insertCustomerStatement.setString(7, new SimpleDateFormat("yyyy-MM-dd").format(customer.getCustomerBirthDate()));

                row += insertCustomerStatement.executeUpdate();

            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (row > 0) {
            System.out.println(row + " Customers was inserted");
        }
                    conn.commit();
conn.close();
        return true;
    }

}