//使用如下类就可以生成图片缩略图class resizeimage{    //图片类型    var $type;    //实际宽度    var $width;    //实际高度    var $height;    //改变后的宽度    var $resize_width;    //改变后的高度    var $resize_height;    //是否裁图    var $cut;    //源图象    var $srcimg;    //目标图象地址    var $dstimg;    //临时创建的图象    var $im;     function resizeimage($img, $wid, $hei,$c,$dstpath)    {        $this->srcimg = $img;        $this->resize_width = $wid;        $this->resize_height = $hei;        $this->cut = $c;        //图片的类型   $this->type = strtolower(substr(strrchr($this->srcimg,"."),1));        //初始化图象        $this->initi_img();        //目标图象地址        $this -> dst_img($dstpath);        //--        $this->width = imagesx($this->im);        $this->height = imagesy($this->im);        //生成图象        $this->newimg();        ImageDestroy ($this->im);    }    function newimg()    {        //改变后的图象的比例        $resize_ratio = ($this->resize_width)/($this->resize_height);        //实际图象的比例        $ratio = ($this->width)/($this->height);        if(($this->cut)=="1")        //裁图        {            if($ratio>=$resize_ratio)            //高度优先            {                $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);                ImageJpeg ($newimg,$this->dstimg);            }            if($ratio<$resize_ratio)            //宽度优先            {                $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));                ImageJpeg ($newimg,$this->dstimg);            }        }        else        //不裁图        {            if($ratio>=$resize_ratio)            {                $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);                ImageJpeg ($newimg,$this->dstimg);            }            if($ratio<$resize_ratio)            {                $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);                imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);                ImageJpeg ($newimg,$this->dstimg);            }        }    }    //初始化图象    function initi_img()    {        if($this->type=="jpg")        {            $this->im = imagecreatefromjpeg($this->srcimg);        }        if($this->type=="gif")        {            $this->im = imagecreatefromgif($this->srcimg);        }        if($this->type=="png")        {            $this->im = imagecreatefrompng($this->srcimg);        }    }    //图象目标地址    function dst_img($dstpath)    {        $full_length  = strlen($this->srcimg);         $type_length  = strlen($this->type);        $name_length  = $full_length-$type_length;          $name         = substr($this->srcimg,0,$name_length-1);        $this->dstimg = $dstpath;  //echo $this->dstimg;    }}  //就只用下面的一句话,就能生成缩略图,其中,源文件和缩略图地址可以相同,200,100分别代表宽和高,第4个参数表示是否截图$resizeimage = new resizeimage($save_path.$file_name, "185", "130", "0",$save_path."c_".$file_name);