可以试下：

package java_jdbc;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class DmText {
    public static void main(String[] args) {
        try {
            // 连接到达梦数据库
            Connection connection = DriverManager.getConnection("jdbc:dm://192.168.186.3:5239", "SYSDBA", "SYSDBA");

            // 创建Statement对象
            Statement statement = connection.createStatement();

            // 执行SQL查询
            ResultSet resultSet = statement.executeQuery("SELECT DESCRIPTION FROM PRODUCT;");

            // 遍历结果集
            while (resultSet.next()) {
                // 将Text类型数据转换为字符串
                BufferedReader reader = new BufferedReader(resultSet.getCharacterStream("DESCRIPTION"));
                StringBuilder stringBuilder = new StringBuilder();
                String line;
                while ((line = reader.readLine()) != null) {
                    stringBuilder.append(line);
                }
                String text = stringBuilder.toString();

                // 打印字符串
                System.out.println(text);
            }

            // 关闭连接
            resultSet.close();
            statement.close();
            connection.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}