gd库图片下载类实现下载网页所有图片的php代码

代码如下：

<?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>

下载的图片本例中保存在当前目录的pic文件夹下！