php 根据URL下载远程图片、压缩包、pdf等文件到本地

//远程路径，名称，文件后缀
function downImgRar($url,$rename,$ext){

    switch ($ext) {
        case ‘jpg‘:        //下载图片
            $file_path = ‘uploads/images/‘;            
            break;
        case ‘png‘:        //下载图片
            $file_path = ‘uploads/images/‘;            
            break;
        case ‘pdf‘:        //下载PDF
            $file_path = ‘uploads/pdf/‘;    
            break;
        case ‘rar‘:        //下载压缩包
            $file_path = ‘uploads/rar/‘;            
            break;
        case ‘zip‘:        //下载压缩包
            $file_path = ‘uploads/rar/‘;            
            break;
        default:
            $file_path = ‘uploads/files/‘;            
        break;
    }
    $ch = curl_init($url);
    curl_setopt($ch,CURLOPT_HEADER,0);
    curl_setopt($ch,CURLOPT_RETURNTRANSFER,1);
    curl_setopt($ch,CURLOPT_BINARYTRANSFER,1);
    $rawdata=curl_exec ($ch);
    curl_close ($ch);
    // 使用中文文件名需要转码
    $fp = fopen($file_path.iconv(‘UTF-8‘,‘GBK‘,$rename).".".$ext,‘w‘);
    fwrite($fp,$rawdata);
    fclose($fp);
    // 返回路径
    return $_SERVER[‘DOCUMENT_ROOT‘].$file_path.$rename.".".$ext;
}

// 下载压缩包
function downRar($file_path)
{
    $file_name = ‘/uploads/rar/2009323162920-维C银翘片说明书.rar‘;
    $file_name = iconv("utf-8","gbk//IGNORE",$file_name); // 特别注意！特别注意！特别注意这里，windows下必须开转码,不然直接文件不存

    $file_path = $_SERVER[‘DOCUMENT_ROOT‘] . $file_name;// 比如windows下这里我的是 "D:/web/public/uploads/rar/2009323162920-维C银翘片说明书.rar"
    //判断如果文件存在,则跳转到下载路径
    if (!file_exists($file_path)) {
        die("文件不存在!");
    }
    $fp = fopen($file_path,"r+") or die(‘打开文件错误‘);   //下载文件必须要将文件先打开。写入内存
    $file_size = filesize($file_path);
    //返回的文件流
    Header("Content-type:application/octet-stream");
    //按照字节格式返回
    Header("Accept-Ranges:bytes");
    //返回文件大小
    Header("Accept-Length:" . $file_size);
    //弹出客户端对话框，对应的文件名
    Header("Content-Disposition:attachment;filename=" . substr($file_name,strrpos($file_name,‘/‘) + 1));
    //防止服务器瞬间压力增大，分段读取
    $buffer = 1024;
    while (!feof($fp)) {
        $file_data = fread($fp,$buffer);
        echo $file_data;
    }
    fclose($fp);

    die("下载成功!");
}