


PHP thumbnail generation code based on GD library (supports jpg, gif, png formats)_PHP tutorial
It’s still the old rule, go directly to the code
<?php /** * 缩略图生成类,使用示例: */ $newimage=new ImageResize(); $newimage->resize("tu.jpg","tu_lit.jpg",1000,1000); echo $newimage->GetLastError(); class ImageResize{ private $localimage;//原图路径 private $remoteimage;//缩略图保存路径 private $localinfo;//原图属性 private $error; function resize($localimg, $remoteimg, $x, $y) { //检测是否支持gd图像处理 if(!$this->_checkenv()){ return false; } $this->localimage = $localimg; $this->remoteimage = $remoteimg; $this->localinfo = getimagesize($this->localimage); //获取本地图像的信息 return $this->_resize($x,$y); } /** * 检测当前环境是否支持GD */ private function _checkenv(){ if(!function_exists('gd_info')){ $this->error[]="当前环境不支持GD图像处理,请先安装GD库并开启PHP相关扩展"; return false; } return true; } /** * 生成缩略图主函数 * @param int $x 指定的缩略图宽度 * @param int $y 指定的缩略图高度 * @return boolean */ private function _resize($x,$y){ if(!$this->localinfo){ $this->error[]="本地图像文件不存在"; return false; } //创建图像句柄 $im=@$this->_create($this->localinfo[2]); if(!$im){ $this->error[]="当前GD库不支持图像类型:{$this->localinfo['mime']}"; return false; } $dstsize=$this->_dstsize($x, $y); $dstim=@imagecreatetruecolor($dstsize["width"],$dstsize["height"]); $whitecolor=@imagecolorallocatealpha($dstim, 0, 0, 0,127); imagefill($dstim,0,0,$whitecolor); $re=@imagecopyresampled($dstim, $im, 0, 0, 0, 0, $dstsize["width"], $dstsize["height"], $this->localinfo[0], $this->localinfo[1]); if(!$re){ $this->error[]="图像重新采样失败"; return false; } if(!imagejpeg($dstim, $this->remoteimage)){ if(!imagepng($dstim,$this->remoteimage)){ if(!imagegif($dstim,$this->remoteimage)){ $this->error[]="保存缩略图到{$this->remoteimage}失败,请检查gd环境是否正常和缩略图文件夹的写入权限。"; return false; } } } $this->error[]="success"; return true; } /** * 根据本地图片类型,创建图片资源 * @param 图像类型代码 $code * @return resource/boolean 成功则返回resourse失败则返回false */ private function _create($code){ $src=$this->localimage; switch ($code){ case 1: return imagecreatefromgif($src); break; case 2: return imagecreatefromjpeg($src); break; case 3: return imagecreatefrompng($src); break; default : return false; break; } } /** * 按比例计算合适的宽度 * @param int $x 指定的缩略图宽度 * @param int $y 指定的缩略图高度 * @return array 包含调整后的缩略图宽度和高度 */ private function _dstsize($x,$y){ list($srcwidth,$srcheight)=$this->localinfo; if(($srcwidth/$srcheight)<($x/$y)){ $x=floor($y*$srcwidth/$srcheight); }else{ $y=floor($x*$srcheight/$srcwidth); } $dstsize["width"]=$x; $dstsize["height"]=$y; return $dstsize; } /** * 获取最后一条错误信息 * return string */ function GetLastError(){ return array_pop($this->error); } /** * 获取所有错误信息 * return array */ function GetAllError(){ return $this->error; } }

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Sessionlockingisatechniqueusedtoensureauser'ssessionremainsexclusivetooneuseratatime.Itiscrucialforpreventingdatacorruptionandsecuritybreachesinmulti-userapplications.Sessionlockingisimplementedusingserver-sidelockingmechanisms,suchasReentrantLockinJ

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