连接数据库查询数据

package dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class Test {
 private String className="A";
 private String url="B";
 private String user="C";
 private String password="D";
 private Connection connection;
 private Statement statement;
 private ResultSet resultSet;

 public Connection getConn() {
  try {
   Class.forName(className);
   connection = DriverManager.getConnection(url, user, password);
  } catch (ClassNotFoundException e) {
   // TODO 自动生成 catch 块
   e.printStackTrace();
  } catch (SQLException e) {
   // TODO 自动生成 catch 块
   e.printStackTrace();
  }
  return connection;
 }
 
 public ResultSet executeQuery(String sql) {
  connection=getConn();
  try {
   statement = connection.createStatement();
   resultSet = statement.executeQuery(sql);
  } catch (SQLException e) {
   // TODO 自动生成 catch 块
   e.printStackTrace();
  }
  return resultSet;
 }
 
 public static void main(String[] args) {
  Test test = new Test();
  ResultSet set = test.executeQuery("select * from T");
 }
}