public class TestJDBC {
    public static void main(String[] args) {
        //數(shù)據(jù)庫連接
        Connection connection = null;
        //預(yù)編譯的Statement，使用預(yù)編譯的Statement提高數(shù)據(jù)庫性能
        PreparedStatement preparedStatement = null;
        //結(jié)果集
        ResultSet resultSet = null;

        try {
            //加載數(shù)據(jù)庫驅(qū)動(dòng)
            Class.forName("com.mysql.jdbc.Driver");

            //通過驅(qū)動(dòng)管理類獲取數(shù)據(jù)庫鏈接
            connection =  DriverManager.getConnection("jdbc:mysql://172.31.50.116:3306/test_ssm?characterEncoding=utf-8", "root", "123456");
            //定義sql語句 ?表示占位符
            String sql = "select * from _user where user_name = ?";
            //獲取預(yù)處理statement
            preparedStatement = connection.prepareStatement(sql);
            //設(shè)置參數(shù)，第一個(gè)參數(shù)為sql語句中參數(shù)的序號(hào)（從1開始），第二個(gè)參數(shù)為設(shè)置的參數(shù)值
            preparedStatement.setString(1, "阿堅(jiān)");
            //向數(shù)據(jù)庫發(fā)出sql執(zhí)行查詢，查詢出結(jié)果集
            resultSet =  preparedStatement.executeQuery();
            //遍歷查詢結(jié)果集
            while(resultSet.next()){
                System.out.println(resultSet.getString("user_id")+"  "+resultSet.getString("user_name"));
            }
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            //釋放資源
            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();
                }
            }

        }

    }
}