gistfile1.php

<?php
	//<meta http-equiv="refresh" content="1;">
	$url='http://www.baidu.com';
	$fileName='test.zip';
	
	
	$fsave = @filesize($fileName) or $fsave=0;
	
	getFile($url,$fsave,20240,$content,$fsize);
	echo $content;
	if($fsave>=$fsize)exit('done');
	$fp = fopen($fileName,'a');
    if (flock($fp,LOCK_EX)){
	    fputs($fp,$content);
	    flock($fp,LOCK_UN);
    }
    
	echo $fsave.'/'.$fsize;
	
	/**
	 * 函数getFile
	 * url 文件连接
	 * start 从文件start字节开始下载
	 * size 下载数据长度
	 * content 返回数据内容
	 * fsize 下载文件大小
	 *
	 */
	function getFile($url,$start=0,$size=102400,&$content,&$fsize){
		$urlInfo = parse_url($url);
		
		//请求头信息
		$header = "GET $url HTTP/1.0\r\n";
		//$header .= "RANGE: bytes=1";
    	//$header .= "RANGE: bytes=$start-".($start+$size);
    	//echo "RANGE: bytes=$start-".($start+$size)."<Br/>";
    	//$header .= "Connection: Close\r\n\r\n";
    	$header .= "connection: keep-alive\r\n\r\n";
    	
    	//连接
    	$fp = fsockopen ($urlInfo['host'],80, $errno, $errstr,30);
    	
    	//检测是否成功
    	if(!$fp){
	       exit('file no exists');
	    }else{
	    	fputs ($fp, $header);
	    }
	    
	    //去除头信息
	    while (!feof($fp)){
	    	$str=fgets ($fp,1024);
	    	echo $str."<br/>";
	    	if(preg_match('/Content-Length: /si', $str, $arr)) {
	    		$arr = explode('/',$arr[1]);
                $fsize1 = trim($arr[1]);
            }
            if(preg_match('/Content-Range: bytes(.*)/si', $str, $arr)) {
                $fsize2 = $arr[1];
            }
	    	if($str=="\r\n")break;
	    }
	    $fsize=!empty($fsize1)?$fsize1:$fsize2;
	    
	    //返回内容
	    fseek($fp,$start);
	    $content=@fread($fp,$size);
	}
?>

gistfile2.txt