mybatis

public static void main(String[] args) {
    Connection connection = null;
    PreparedStatement preparedStatement = null;
    ResultSet resultSet = null;
    
    try {
        //1、加载数据库驱动
        Class.forName("com.mysql.jdbc.Driver");
        //2、通过驱动管理类获取数据库连接
        connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8", "root", "root");
        //3、定义sql语句 ?表示占位符
        String sql = "select * from user where username = ?";
        //4、获取预处理statement
        preparedStatement = connection.prepareStatement(sql);
        //5、给sql语句中的？赋值；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");
        //6、向数据库发出sql执行查询，查询出结果集
        resultSet = preparedStatement.executeQuery();
        //7、遍历结果集
        while(resultSet.next()){
            System.out.println(resultSet.getString("id")+"  "+resultSet.getString("username"));
        }
    } catch (Exception e) {
        e.printStackTrace();
    }finally{
        //8、释放资源
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(preparedStatement!=null){
            try {
                preparedStatement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(connection!=null){
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}