<?php

class Session

{

	private $db;				// 设置数据库变量

	private $expiry = 3600;		// 设置Session失效时间	

	public function Session()

	{

		session_set_save_handler(array(& $this,'_session_open'),

								array(& $this,'_session_close'),

								array(& $this,'_session_read'),

								array(& $this,'_session_write'),

								array(& $this,'_session_destroy'),

								array(& $this,'_session_gc')

		);

	}	

	public function _session_open($save_path,$session_name)

	{

		$this->db = mysql_connect('localhost','root','123456') or die ("数据库连接失败！");

		mysql_select_db("db_database11",$this->db);

		return(true);

	}

	public function _session_close()

	{

		mysql_close($this->db);

		return(true);

	}

	public function _session_read($key)

	{

		$time = time();							// 设定当前时间

		$sql = "select session_data from tb_session where session_key = '$key' and session_time > $time";

		$result = mysql_query($sql,$this->db);

		$row = mysql_fetch_array($result);

		if ($row)

		{

			return($row['session_data']);			// 返回Session名称及内容

		}else

		{

			return(false);

		}

	}

	public function _session_write($key,$data)

	{

		$lapse_time = time() + $this->time;					// 得到Unix时间戳

		$sql = "select session_data from tb_session where session_key = '$key' and session_time > $lapse_time";

		$result = mysql_query($sql,$this->db);

		if (mysql_num_rows($result) == 0 )				// 没有结果

		{

			$sql = "insert into tb_session values('$key','$data',$lapse_time)";		// 插入数据库sql语句

			$result = mysql_query($sql,$this->db);

		}else

		{

			$sql = "update tb_session set session_key = '$key',session_data = '$data',session_time = $lapse_time where session_key = '$key'";												// 修改数据库sql语句

			$result = mysql_query($sql,$this->db);

		}

		return($result);

	}

	public function _session_destroy($key)

	{

		$sql = "delete from tb_session where session_key = '$key'";					// 删除数据库sql语句

		$result = mysql_query($sql,$this->db);

		return($result);

	}

	public function _session_gc($expiry_time)

	{

		$expiry_time = time();									// 将参数$expiry_time赋值为当前时间戳

		$sql = "delete from tb_session where expiry_time < $expiry_time";	// 删除数据库sql语句

		$result = mysql_query($sql,$this->db);

		return($result);

	}

}

$_session_new = new Session();

session_start();

$_SESSION['SID'] = true;

?>