PHP implements the method of resuming the download at a breakpoint, PHP implements the resumable download at the breakpoint_PHP tutorial

/*
* PHP download breakpoint resume
*/
function dl_file_resume($file){

//Check whether the file exists
If (!is_file($file)) { die("404 File not found!"); }
       
$len = filesize($file);//Get file size
$filename = basename($file);//Get the file name
$file_extension = strtolower(substr(strrchr($filename,"."),1));//Get the file extension
       
//Indicate the output browser format based on the extension
switch( $file_extension ) {
case "exe": $ctype="application/octet-stream"; break;
          case "zip": $ctype="application/zip"; break;
case "mp3": $ctype="audio/mpeg"; break;
case "mpg":$ctype="video/mpeg"; break;
case "avi": $ctype="video/x-msvideo"; break;
​​​​Default: $ctype="application/force-download";
}
       
//Begin writing headers
header("Cache-Control:");
header("Cache-Control: public");
       
//Set the output browser format
header("Content-Type: $ctype");
If (strstr($_SERVER['HTTP_USER_AGENT'], "MSIE")) {//If it is IE browser
​​​​ # workaround for IE filename bug with multiple periods / multiple dots in filename
            # that adds square brackets to filename - eg. setup.abc.exe becomes setup[1].abc.exe
           $iefilename = preg_replace('/./', '%2e', $filename, substr_count($filename, '.') - 1);
header("Content-Disposition: attachment; filename="$iefilename"");
} else {
header("Content-Disposition: attachment; filename="$filename"");
}
header("Accept-Ranges: bytes");
       
$size=filesize($file);
//If there is $_SERVER['HTTP_RANGE'] parameter
If(isset($_SERVER['HTTP_RANGE'])) {
/* --------------------------
Range header field The Range header field can request one or more sub-ranges of an entity. For example, represents the first 500 bytes: bytes=0-499 represents the second 500 bytes: bytes=500-999 represents the last 500 bytes: bytes=-500 represents the range after 500 bytes: bytes=500- The first and last bytes: bytes=0-0,-1 Specify several ranges at the same time: bytes=500-600,601-999 But the server can ignore this request header. If the unconditional GET contains the Range request header, the response will be in status Code 206 (PartialContent) is returned instead of 200 (OK).
---------------------------*/
 
// Connect again after the breakpoint. The value of $_SERVER['HTTP_RANGE'] bytes=4390912-
 
list($a, $range)=explode("=",$_SERVER['HTTP_RANGE']);
//if yes, download missing part
        str_replace($range, "-", $range);//What is this sentence for? . . .
$size2=$size-1;//The total number of bytes in the file
          $new_length=$size2-$range;//Get the length of the next download
header("HTTP/1.1 206 Partial Content");
          header("Content-Length: $new_length");//Input total length
header("Content-Range: bytes $range$size2/$size");//Content-Range: bytes 4908618-4988927/4988928 95% of the time
} else {//First connection
         $size2=$size-1;
header("Content-Range: bytes 0-$size2/$size"); //Content-Range: bytes 0-4988927/4988928
          header("Content-Length: ".$size);//Output total length
}
//Open file
$fp=fopen("$file","rb");
//Set the pointer position
fseek($fp,$range);
//Unreal output
While(!feof($fp)){
//Set the maximum file execution time
​​​​ set_time_limit(0);
​​​​print(fread($fp,1024*8));//Output file
​​​​flush();//Output buffer
         ob_flush();
}
fclose($fp);
exit;
}

dl_file_resume("1.zip");//1.zip file in the same directory

//------------------------------------------

//File downloads that can be resumed at breakpoints are not supported.

//------------------------------------------

downFile("1.zip");

function downFile($sFilePath)
{
If(file_exists($sFilePath)){
         $aFilePath=explode("/",str_replace("\","/",$sFilePath),$sFilePath);
         $sFileName=$aFilePath[count($aFilePath)-1];
          $nFileSize=filesize ($sFilePath);
header ("Content-Disposition: attachment; filename=" . $sFileName);
header ("Content-Length: " . $nFileSize);
header ("Content-type: application/octet-stream"); ​​
        readfile($sFilePath);
}
else
{
echo("File does not exist!");
}
}
?>