将sql ResultSet写入csv文件。

import java.io.FileWriter;
import java.io.IOException;
import java.sql.*;

public class ResultSetToCSV {
    public static void main(String[] args) {
        String jdbcUrl = "jdbc:mysql://localhost:3306/mydatabase";
        String username = "username";
        String password = "password";
        String query = "SELECT * FROM mytable";

        try (Connection connection = DriverManager.getConnection(jdbcUrl, username, password);
             Statement statement = connection.createStatement();
             ResultSet resultSet = statement.executeQuery(query);
             FileWriter writer = new FileWriter("output.csv")) {

            // 写入CSV文件头部
            ResultSetMetaData metaData = resultSet.getMetaData();
            int columnCount = metaData.getColumnCount();
            for (int i = 1; i <= columnCount; i++) {
                writer.append(metaData.getColumnName(i));
                if (i < columnCount) {
                    writer.append(",");
                }
            }
            writer.append("\n");

            // 写入ResultSet中的数据
            while (resultSet.next()) {
                for (int i = 1; i <= columnCount; i++) {
                    writer.append(resultSet.getString(i));
                    if (i < columnCount) {
                        writer.append(",");
                    }
                }
                writer.append("\n");
            }

            System.out.println("成功将ResultSet写入CSV文件！");
        } catch (SQLException | IOException e) {
            e.printStackTrace();
        }
    }
}