import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException; import com.mysql.jdbc.Connection;import com.mysql.jdbc.PreparedStatement; public class Test {  public static void main(String[] args) {         //聲明Connection對象    Connection conn = null;    PreparedStatement preparedStatement = null;    ResultSet resultSet = null;    //驅動程序名    String driver = "com.mysql.jdbc.Driver";    //用戶名    String user = "root";    //密碼    String password = "1234";    //url    String url = "jdbc:mysql://localhost:3306/db_person";         try {      String sql = "SELECT * FROM student";      //1.加載驅動      Class.forName(driver);      //2.獲得connect連接      conn = (Connection) DriverManager.getConnection(url, user, password);      //3.獲得PreparedStatement      preparedStatement = (PreparedStatement) conn.prepareStatement(sql);      //4.獲得結果集      resultSet = preparedStatement.executeQuery();             while(resultSet.next()) {        int id = resultSet.getInt(1);        String name = resultSet.getString(2);        String sex = resultSet.getString(3);        int age = resultSet.getInt(4);                 System.out.println(id +" "+ name + " " + sex + " " + age);      }           } catch (Exception e) {      // TODO Auto-generated catch block      e.printStackTrace();    }finally {      if(resultSet != null) {        try {          resultSet.close();        } catch (SQLException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }      }             if(preparedStatement != null) {        try {          preparedStatement.close();        } catch (SQLException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }      }             if(conn != null) {        try {          conn.close();        } catch (SQLException e) {          // TODO Auto-generated catch block          e.printStackTrace();        }      }           }  }}