java连接mysql数据库及简单操作dao

package com.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.SQLException; public class ConMysqlDao { static { // 加载驱动程序 try { Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); System.out.println("驱动加载失败"); } } // 数据库连接字符串 private String url = "jdbc:mysql://localhost:3306/petinfo"; // 用户名 private String userName = "root"; // 密码 private String passWord = "123456"; // 连接对象 public Connection con = null; // 语句对象 public PreparedStatement ps = null; // 数据库连接方法 public void prepareConnection() { try { if (con == null || con.isClosed()) { con = DriverManager.getConnection(url, userName, passWord); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); throw new RuntimeException("连接异常:" + e.getMessage()); } } // 关闭方法 public void close() { try { if (ps != null) { ps.close(); } if (con != null) { con.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); throw new RuntimeException("关闭连接异常:" + e.getMessage()); } } // 操作回滚 public void rollback() { try { con.rollback(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); throw new RuntimeException("回滚失败:" + e.getMessage()); } } }