memcache使用实例|PHP

首先，判断memcache中是否存在key，如果有则从memcache中取值；如果没有相应的key，则从去网页中抓取数据，如果抓取成功，则存入db,写入memcache并读取，如果抓取不成功，则直接mysql中取值，并将取出来的值放入memcache。

<?phpinclude('inc/common.inc.php');if (! isset($city) || ! is_array($city) ) {exit;}//print_r ($city);exit;$mem = new Memcache();$mem-> connect('localhost', '11211');$expires=15*60;//check if cache exitsif(($value = $mem-> get($city)) != FALSE) {echo "get key from memcache: "."<br />";// $return=$mem->get($city);// echo json_encode($return);}//ifelse {$resultJson=fetch_data();echo count($resultJson)."<br />";if(count($resultJson)==1 || empty($resultJson)){//从mysql中取值echo "get key from mysql:"."<br />";$query="select * from pm25";$result=mysql_query ($query) ;while ($row = mysql_fetch_assoc($result)){$rows[]=$row;}//将获取的值数组存入memcachefor($i=0;$i<count($rows);$i++){$k[$i]=$rows[$i]['city'];$v[$i]['city']=$rows[$i]['city'];$v[$i]['pm25']=$rows[$i]['pm25'];$mem -> set($k[$i], $v[$i], false, $expires);}// $return=$mem->get($city);// echo json_encode($return);}//ifelse{echo "get key from new_writed mysql:"."<br />";write_db($resultJson);$query="select * from pm25";$result=mysql_query ($query) ;while ($row = mysql_fetch_assoc($result)){$rows[]=$row;}//write memcachefor($i=0;$i<count($rows);$i++){$k[$i]=$rows[$i]['city'];$v[$i]['city']=$rows[$i]['city'];$v[$i]['pm25']=$rows[$i]['pm25'];$mem -> set($k[$i], $v[$i], false, $expires);}// $return=$mem->get($city);// echo json_encode($return);}//else}//elseforeach ($city as $k=>$v){$return[$k]=$mem->get($v);}echo json_encode($return);function fetch_data() {$url="http://www.example.com";//$url="";$data = http_get($url);$getJson = json_decode($data, true);return $getJson;} //func fetch_datafunction write_db($getJson){$sql="DELETE FROM pm25";mysql_query($sql);//sort the json.txtforeach ($getJson as $key => $row) {$area[$key] = $row['area'];$pm2_5[$key]= $row['pm2_5'];}array_multisort($area, SORT_ASC,$pm2_5,SORT_ASC,$getJson);for($i=0;$i<count($getJson)-1;$i++){if($getJson[$i]['pm2_5']==0)$count=0;else$count=1;$sum=$getJson[$i]['pm2_5'];for($j=$i+1;$j<count($getJson);$j++,$i++){if(strcmp($getJson[$j]['area'],$getJson[$i]['area'])==0 ){if($getJson[$j]['pm2_5']==0 ){continue;}else{$count++;$sum+=$getJson[$j]['pm2_5'];$pm2_5=$sum/$count;}}else{//insert into mysql$result['city']=$getJson[$i]['area'];$result['pm25']=intval($pm2_5);$query="insert into pm25(city,pm25) values ('".$result['city']."',".$result['pm25'].")";mysql_query($query);break;}}}return $getJson;}//func write_db$mem -> close();?>