<?php
/**
+----------------------
 * Mysql操作类
+----------------------
 * 文件名称  Db.class.php
+----------------------
 * 文件描述  mysql操作类
+----------------------
 */
class Db{
    //数据库连接标识
    protected $link = null;
    //当前操作的表
    public $table = '';
    //查询参数
    protected $options = array();
    //当前执行的SQL语句
    protected $sql = '';
    //用什么编码传递数据
    protected $dbCharset = 'utf8';

    //缓存路径
    protected $cachePath = './cache/';
    //缓存扩展名
    protected $cacheFileExt = "php";
    //缓存文件名
    protected $cacheFileName;
    //是否缓存
    protected $cache = false;
    //缓存更新时间秒数
    protected $cacheLimitTime = 60;

    //数据返回类型, 1代表数组, 2代表对象
    protected $returnType = 1;

  /*
   * 根据当前动态文件生成缓存文件名
   */
	function setCacheFileName($fileName) {
		$cacheFileName = $this->cachePath . strtoupper(md5($fileName)).".".$this->cacheFileExt;
		$this->cacheFileName=$cacheFileName;
    }
  /*
   * 根据当前动态文件生成缓存文件名
   */
	function getCacheFileName() {
		return  $this->cacheFileName;
    }
    /**
     * 连接数据库
     *
     * @access      public
     * @param       array    $db  数据库配置
     * @return      resource 数据库连接标识
     */
    public function connect($db){
        //根据配置使用不同函数连接数据库
        $db['host'] = isset($db['port']) ? $db['host'].':'.$db['port']: $db['host'];
        $db['char'] = isset($db['char']) ? $db['char']: $this->dbCharset;
        $func = $db['pconnect'] ? 'mysql_pconnect' : 'mysql_connect';
        $this->link = $func($db['host'], $db['user'], $db['pwd']);
        mysql_select_db($db['database'], $this->link);
        mysql_query("SET NAMES '{$db['char']}'");
        $this->cachePath = isset($db['cachepath']) ? $db['cachepath']: $this->cachePath;
        return $this->link;
    }
    /**
     * 查询符合条件的一条记录
     *
     * @access      public
     * @param       string    $where  查询条件
     * @param       string    $field  查询字段
     * @param       string    $table  表
     * @return      mixed             符合条件的记录
     */
    public function find($where = NULL, $field = '*', $table = ''){
        return $this->findAll($where = NULL, $field = '*', $table = '', FALSE);
    }
    /**
     * 查询符合条件的所有记录
     *
     * @access      public
     * @param       string    $where  查询条件
     * @param       string    $field  查询字段
     * @param       string    $table  表
     * @return      mixed             符合条件的记录
     */
    public function findAll($where = NULL, $field = '*', $table = '', $all = TRUE){
        $this->options['where'] = is_null($where) ? @$this->options['where']: $where;
        $this->options['field'] = isset($this->options['field']) ? $this->options['field']: $field;
        $this->options['table'] = $table == '' ? $this->table: $table;
        $sql = "SELECT {$this->options['field']} FROM `{$this->options['table']}` ";
        $sql .= isset($this->options['join']) ? ' LEFT JOIN '.$this->options['join']: '';
        $sql .= isset($this->options['where']) ? ' WHERE '.$this->options['where']: '';
        $sql .= isset($this->options['group']) ? ' GROUP BY '.$this->options['group']: '';
        $sql .= isset($this->options['having']) ? ' HAVING '.$this->options['having']: '';
        $sql .= isset($this->options['order']) ? ' ORDER BY '.$this->options['order']: '';
        $sql .= isset($this->options['limit']) ? ' LIMIT '.$this->options['limit']: '';
        $this->sql = $sql;
        $row = NULL;
        //如果开启了缓存, 那么重缓存中获取数据
        if ($this->cache === TRUE){
			$this->setCacheFileName($this->sql);
            $row = $this->readCache();
        }
        //如果读取失败, 或则没有开启缓存
        if (is_null($row)){
            $result = $this->query();
            $row = $all === TRUE ? $this->fetchAll($result): $this->fetch($result);
            //如果开启了缓存, 那么就写入
            if ($this->cache === TRUE){
                $this->writeCache($row);
            }