关于mysql，sqlserverl，与oracle数据库链接总结

首先准备工具类，其中须要修改的地方分别作标注

代码一sqlserver为例，不一样数据库只需修改我所标记的第一处和第二处

mysql     第一处应为：com.mysql.jdbc.Driver   第二处url 为：jdbc:mysql://127.0.0.1:3306/javaweb    //3306位端口，javaweb为数据库名

Oracle   第一处应为：oracle.jdbc.OracleDriver  第二处url 为：jdbc:oracle:thin:@localhost:1522:orcl   //1522为端口，orcl为数据库名

sql语句因数据库不一样略有差别，但都大同小异。

package Util; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DBUtil { public  static Connection getConnection(){ try { Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver").newInstance(); //1.此处根据数据库修改 } catch (InstantiationException | IllegalAccessException | ClassNotFoundException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } String user = "sa"; 　　　　　　 //用户名 String password = "123456"; //密码 String url = "jdbc:sqlserver://127.0.0.1:1433;DatabaseName=keji"; //2.数据库名 Connection connection = null; try { //2 �������Ӷ���connection
             connection = DriverManager.getConnection(url,user,password); } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } return connection; } public static void close(Connection connection ) { try { if (connection != null) { connection.close(); } } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } } public static void close(PreparedStatement preparedStatement ) { try { if (preparedStatement != null) { preparedStatement.close(); } } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } } public static void close(ResultSet resultSet ) { try { if (resultSet != null) { resultSet.close(); } } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } } }

对数据库操做代码

简单的插入

public void add (User user){ Connection connection=DBUtil.getConnection(); String sql = "select count(*) from t_user where username = ?"; PreparedStatement preparedStatement = null; ResultSet resultSet = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getUsername()); resultSet = preparedStatement.executeQuery(); while(resultSet.next()) { if (resultSet.getInt(1) > 0) { throw new UserException("用户名存在") ; } } sql = "insert into t_user(username,password) values (?,?)"; preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getUsername()); preparedStatement.setString(2, user.getPassword()); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); } finally{ DBUtil.close(resultSet); DBUtil.close(preparedStatement); DBUtil.close(connection); } }

删除

public void delete(String username) { // TODO Auto-generated method stub
        Connection connection = DBUtil.getConnection(); String sql = "delete from t_user where username = ?"; PreparedStatement preparedStatement = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, username); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); }finally { DBUtil.close(preparedStatement); DBUtil.close(connection); } }

修改

public void update(User user) { // TODO Auto-generated method stub
        Connection connection = DBUtil.getConnection(); //׼��sql���
        String sql = "update t_user set password = ? where username = ?"; //������䴫�����
        PreparedStatement preparedStatement = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, user.getPassword()); preparedStatement.setString(2, user.getUsername()); preparedStatement.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); }finally { DBUtil.close(preparedStatement); DBUtil.close(connection); } }

查询

public User load(String username) { // TODO Auto-generated method stub
        Connection connection = DBUtil.getConnection(); //׼��sql���
        String sql = "select * from t_user  where username = ?"; //������䴫�����
        PreparedStatement preparedStatement = null; ResultSet resultSet = null; User user = null; try { preparedStatement = connection.prepareStatement(sql); preparedStatement.setString(1, username); resultSet = preparedStatement.executeQuery(); while(resultSet.next()) { user = new User(); user.setId(resultSet.getInt("id")); user.setUsername(username); user.setBalance(resultSet.getFloat("balance")); user.setPassword(resultSet.getString("password")); user.setType(resultSet.getInt("type")); user.setCredit(resultSet.getFloat("credit")); } } catch (SQLException e) { // TODO Auto-generated catch block
 e.printStackTrace(); }finally { DBUtil.close(resultSet); DBUtil.close(preparedStatement); DBUtil.close(connection); } return user; }