[PHP]代码    

class Db{   protected $_connect;   protected $_db = Array();   protected $_cache = Array();     public function __construct($args){    list($this->_db,$this->_cache) = $args;   }   protected function connect($db){    $this->_connect = mysql_connect($db['hostname'],$db['username'],$db['password']);    mysql_set_charset('UTF8');    mysql_select_db($db['databasename'],$this->_connect);   }   /**    *作用：获取表中数据，并将所查询到的数据格式化返回，返回格式是数组形式！    *$sql：传入的待执行的SQL语句，必须而且只能是SELECT    *    */   public function fetch($sql){    $result = '';    if(isset($this->_cache['expire'])){     $name = md5(strtolower(str_replace(' ','',$sql)));     $dir = substr($name,0,2);     $dir = $this->_cache['dir'].'/'.$dir;     !is_dir($dir) && mkdir($dir,0777);     !is_dir($dir) && mkdir($dir,0777);     $this->_cache['path'] = $dir.'/'.$name;     if(is_file($this->_cache['path']) && $this->check_expire()){      $result = $this->get();     }    }    if($result == ''){     $data = $this->exec($sql);     $result = Array();     while($result[] = mysql_fetch_array($data,MYSQL_ASSOC)){} //去除索引     mysql_free_result($data);     array_pop($result);     isset($this->_cache['expire']) && $this->write($result);    }    return $result;   }   /**    *作用：执行所有的SQL语句，但不包括SELECT！    *$sql：传入的待执行的SQL语句，不能为SELECT    *返回值：TRUE OR FALSE    */   public function exec($sql){    if($this->_connect === null) $this->connect($this->_db); //进行数据链接    if( $result = mysql_query($sql, $this->_connect) ){     return $result;    }else{     die("{$sql}<br />执行错误: " . mysql_error());    }   }   /**    *作用：执行数据库插入语句，只能是INSERT语句！    *$v：传入的待执行的条件，是数组格式table代表待执行插入的表，row是字段，value是待插入的值    *返回值：mysql_insert_id() OR FALSE    */    public function insert($table,$field,$ignore = 0){    $D = Array('field'=>'','val'=>'');    foreach($field AS $key => $v){     $D['field'] .= $key.',';     $D['val'] .= "'{$this->escape($v)}',";    }    $D['field'] = rtrim($D['field'],',');    $D['val'] = rtrim($D['val'],',');    $ignore = $ignore > 0 ? 'IGNORE' : '';    $sql = "INSERT {$ignore} INTO {$this->_db['perfix']}{$table}({$D['field']}) VALUES({$D['val']})";    if($this->exec($sql)){     $insert_id = mysql_insert_id();     return is_numeric($insert_id) ? $insert_id : TRUE;    }else{     return FALSE;    }   }   public function update($table,$field){    $D = Array('where'=>'','str'=>'');    $index = 0;    foreach($field AS $key => $v){     $index == 0 ? $D['where'] = "{$key} = '{$this->escape($v)}'" : $D['str'] .= "{$key} = '{$this->escape($v)}',";     $index++;    }    $D['str'] = rtrim($D['str'],',');    $sql = "UPDATE {$this->_db['perfix']}{$table} SET {$D['str']} WHERE {$D['where']}";    return $this->exec($sql);        }   public function delete($table,$field){    $str = '';    foreach($field AS $key => $v){     $str = "{$key} = '{$v}'";    }    $sql = 'DELETE FROM '.$this->_db['perfix'].$table.' WHERE '.$str.' LIMIT 1';    return $this->exec($sql);   }   public function sum($table,$condition){    $totle = $this->fetch('SELECT COUNT(*) AS totle FROM '.$this->_db['perfix'].$table.' WHERE '.$condition);    return $totle[0]['totle'];   }   /**     *作用：对输入特殊字符进行过滤    *$v：待传入检测的参数    *返回值：检测完的参数    */    public function escape($v){    return mysql_real_escape_string($v);   }   /*    *作用：进行缓存判断     */   public function cache($name,$expire=100000000){    $this->_cache['expire'] = $expire;    return $this;   }   public function check_expire(){    return (filemtime($this->_cache['path']) + $this->_cache['expire']) > strtotime("now");   }      public function write($data){    $f = fopen($this->_cache['path'], 'w');          if ($f) {              flock($f, LOCK_EX);              fseek($f, 0);              ftruncate($f, 0);              $tmp = fwrite($f, serialize($data));              if (!($tmp === false)) {                  $result = true;              }              fclose($f);          }    chmod($this->_cache['path'],0777);   }   public function get(){    $f = fopen($this->_cache['path'], 'r');     $data = fread($f,filesize($this->_cache['path']));    fclose($f);    return unserialize($data);   }   public function delete_dir($dir = ''){    $dir = empty($dir) ? $this->_cache['dir'] : $dir;    !is_dir($dir) && exit;    $d = opendir($dir);    $i = 0;    while(($file = readdir($d)) !== false){     $path = $dir.'/'.$file;     if($i > 1) is_file($path) ? unlink($path) : $this->delete_dir($path);     $i++;    }    closedir($d);    rmdir($dir);   }   public function __destruct(){    isset($this->_connect) && mysql_close($this->_connect);   }   }