gd库图片下载类实现下载网页所有图片的php代码

<?php
header("Content-type:text/html ; charset=utf-8");
if (!empty($_POST[submit])){
$url = $_POST[url];
//为了获取相对路径的图片所做的操作
$url_fields = parse_url($url);
$main_url = $url_fields[host];
$base_url = substr($url,0,strrpos($url, /)+1);
//获取网页内容
//设置代理服务器
$opts = array(http=>array(request_fulluri=>true));
$context = stream_context_create($opts);
$content = file_get_contents($url,false,$context);
//匹配img标签,将所有匹配字符串保存到数组$matches
$reg = "/<img.*?src=\"(.*?)\".*?>/i";
preg_match_all($reg, $content, $matches);
$count = count($matches[0]);
for ($i=0; $i<$count; $i++){
/*将所有图片的url转换为小写
*$matches[1][$i] = strtolower($matches[1][$i]);
*/
//如果图片为相对路径就转化为全路径
if (!strpos(a.$matches[1][$i], http)){
//因为/是第0个位置
if (strpos(a.$matches[1][$i], /)){
$matches[1][$i] = http://.$main_url.$matches[1][$i];
}else{
$matches[1][$i] = $base_url.$matches[1][$i];
}
}
}
//过滤重复的图片
$img_arr = array_unique($matches[1]);
//实例化图片下载类
$getImg = new DownImage();
$url_count = count($img_arr);
for ($i=0; $i<$url_count; $i++){
$getImg->source = $img_arr[$i];
$getImg->save_address = ./pic/;
$file = $getImg->download();
}
echo "下载完成！哈哈，简单吧！";
}
class DownImage{
public $source;//远程图片URL
public $save_address;//保存本地地址
public $set_extension; //设置图片扩展名
public $quality; //图片的质量（0'100,100最佳，默认75左右）
//下载方法（选用GD库图片下载）
public function download(){
//获取远程图片信息
$info = @getimagesize($this->source);
//获取图片扩展名
$mime = $info[mime];
$type = substr(strrchr($mime, /), 1);
//不同的图片类型选择不同的图片生成和保存函数
switch($type){
case jpeg:
$img_create_func = imagecreatefromjpeg;
$img_save_func = imagejpeg;
$new_img_ext = jpg;
$image_quality = isset($this->quality) ? $this->quality : 100;
break;
case png:
$img_create_func = imagecreatefrompng;
$img_save_func = imagepng;
$new_img_ext = png;
break;
case bmp:
$img_create_func = imagecreatefrombmp;
$img_save_func = imagebmp;
$new_img_ext = bmp;
break;
case gif:
$img_create_func = imagecreatefromgif;
$img_save_func = imagegif;
$new_img_ext = gif;
break;
case vnd.wap.wbmp:
$img_create_func = imagecreatefromwbmp;
$img_save_func = imagewbmp;
$new_img_ext = bmp;
break;
case xbm:
$img_create_func = imagecreatefromxbm;
$img_save_func = imagexbm;
$new_img_ext = xbm;
break;
default:
$img_create_func = imagecreatefromjpeg;
$img_save_func = imagejpeg;
$new_img_ext = jpg;
}
//根据是否设置扩展名来合成本地文件名
if (isset($this->set_extension)){
$ext = strrchr($this->source,".");
$strlen = strlen($ext);
$newname = basename(substr($this->source,0,-$strlen))...$new_img_ext;
}else{
$newname = basename($this->source);
}

//生成本地文件路径
$save_address = $this->save_address.$newname;
$img = @$img_create_func($this->source);
if (isset($image_quality)){
$save_img = @$img_save_func($img,$save_address,$image_quality);
}else{
$save_img = @$img_save_func($img,$save_address);
}
return $save_img;
}
}
?>
<form method="POST" action="">
远程url地址：<input type="text" name="url" size=30 />
<input type="submit" name="submit" value="下载该页面所有图片" />
</form>