public static void main(String[] args) {// 数据库连接Connection connection = null;//Statement，使用预编译的Statement提高数据库性能Statement statement = null;// 结果 集ResultSet resultSet = null;try {// 加载数据库驱动Class.forName("com.mysql.jdbc.Driver");// 通过驱动管理类获取数据库链接connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/day02?characterEncoding=utf-8","root", "");// 定义sql语句 ?表示占位符String sql = "select * from user where username = '王五'";// 获取预处理statementstatement = connection.createStatement();//新增statement.executeUpdate("INSERT INTO USER (username ,birthday,sex)VALUES('fyp','2014-01-02',1)",Statement.RETURN_GENERATED_KEYS);connection.setAutoCommit(false);           connection.commit();} catch (Exception e) {e.printStackTrace();} finally {// 释放资源if (resultSet != null) {try {resultSet.close();} catch (SQLException e) {// TODO Auto-generated catch block
                    e.printStackTrace();}}if (statement != null) {try {statement.close();} catch (SQLException e) {// TODO Auto-generated catch block
                    e.printStackTrace();}}if (connection != null) {try {connection.close();} catch (SQLException e) {// TODO Auto-generated catch block
                    e.printStackTrace();}}}}

    public static void main(String[] args) {// 数据库连接Connection connection = null;// 预编译的Statement，使用预编译的Statement提高数据库性能PreparedStatement preparedStatement = null;// 结果 集ResultSet resultSet = null;try {// 加载数据库驱动Class.forName("com.mysql.jdbc.Driver");// 通过驱动管理类获取数据库链接connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/day02?characterEncoding=utf-8","root", "");// 定义sql语句 ?表示占位符String sql = "select * from user where username = ?";// 获取预处理statement
            connection.createStatement();preparedStatement = connection.prepareStatement(sql);// 设置参数，第一个参数为sql语句中参数的序号（从1开始），第二个参数为设置的参数值preparedStatement.setString(1, "王五");// 向数据库发出sql执行查询，查询出结果集resultSet = preparedStatement.executeQuery();// 遍历查询结果集while (resultSet.next()) {System.out.println(resultSet.getString("id") + "  " + resultSet.getString("username"));}} catch (Exception e) {e.printStackTrace();} finally {// 释放资源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 (connection != null) {try {connection.close();} catch (SQLException e) {// TODO Auto-generated catch block
                    e.printStackTrace();}}}}