This article mainly introduces the file operation class and file download function implemented by PHP. It analyzes PHP's functions of reading, writing, creating and downloading files in the form of examples. Friends in need can refer to the following

The details are as follows:

File operation class:

<?php
 // Copyright 2005, Lee Babin (lee@thecodeshoppe.com)
 // This code may be used and redistributed without charge
 // under the terms of the GNU General Public
 // License version 2.0 or later -- www.gnu.org
 // Subject to the retention of this copyright
 // and GPL Notice in all copies or derived works
 class cfile {
  //The path to the file we wish to work with.
  protected $thepath;
  //Error messages in the form of constants for ease of use.
  const FOUNDERROR = "Sorry, the file in question does not exist.";
  const PERMERROR = "Sorry, you do not have the proper permissions on this file";
  const OPENERROR = "Sorry, the file in question could not be opened.";
  const CLOSEERROR = "Sorry, the file could not be closed.";
  //The constructor function.
  public function __construct (){
   $num_args = func_num_args();
   if($num_args > 0){
    $args = func_get_args();
    $this->thepath = $args[0];
   }
  }
  //A function to open the file.
  private function openfile ($readorwrite){
    //First, ensure the file exists.
    try {
      if (file_exists ($this->thepath)){
        //Now, we need to see if we are reading or writing or both.
        $proceed = false;
        if ($readorwrite == "r"){
          if (is_readable($this->thepath)){
            $proceed = true;
          }
        } elseif ($readorwrite == "w"){
          if (is_writable($this->thepath)){
            $proceed = true;
          }
        } else {
          if (is_readable($this->thepath) && is_writable($this->thepath)){
            $proceed = true;
          }
        }
        try {
          if ($proceed){
            //We can now attempt to open the file.
            try {
              if ($filepointer = fopen ($this->thepath, $readorwrite)){
                return $filepointer;
              } else {
                throw new exception (self::OPENERROR);
                return false;
              }
            } catch (exception $e) {
              echo $e->getmessage();
            }
          } else {
            throw new exception (self::PERMERROR);
          }
        } catch (exception $e) {
          echo $e->getmessage();
        }
      } else {
        throw new exception (self::FOUNDERROR);
      }
    } catch (exception $e) {
      echo $e->getmessage();
    }
  }
  //A function to close a file.
  function closefile () {
    try {
      if (!fclose ($this->thepath)){
        throw new exception (self::CLOSEERROR);
      }
    } catch (exception $e) {
      echo $e->getmessage();
    }
  }
  //A function to read a file, then return the results of the read in a string.
  public function read () {
    //First, attempt to open the file.
    $filepointer = $this->openfile ("r");
    //Now, return a string with the read data.
    if ($filepointer != false){
      //Then we can read the file.
      return fgets ($filepointer);
    }
    //Lastly, close the file.
    $this->closefile ();
  }
  //A function to write to a file.
  public function write ($towrite) {
    //First, attempt to open the file.
    $filepointer = $this->openfile ("w");
    //Now, return a string with the read data.
    if ($filepointer != false){
      //Then we can read the file.
      return fwrite ($filepointer, $towrite);
    }
    //Lastly, close the file.
    $this->closefile ();
  }
  //A function to append to a file.
  public function append ($toappend) {
    //First, attempt to open the file.
    $filepointer = $this->openfile ("a");
    //Now, return a string with the read data.
    if ($filepointer != false){
      //Then we can read the file.
      return fwrite ($filepointer, $toappend);
    }
    //Lastly, close the file.
    $this->closefile ();
  }
  //A function to set the path to a new file.
  public function setpath ($newpath) {
    $this->thepath = $newpath;
  }
 }
?>

<?php
  $myfile = new cfile ("test.txt");
  //Now, let&#39;s try reading it.
  echo $myfile->read();
  //Then let&#39;s try writing to the file.
  $myfile->write ("Hello World!");
  //Then, let&#39;s try appending.
  $myfile->append ("Hello Again!");
?>

File download:

<?php
$filename = &#39;file1.txt&#39;;
$file = fopen($filename, &#39;r&#39;);
Header("Expires: 0");
Header("Pragma: public");
Header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
Header("Cache-Control: public");
Header("Content-Length: ". filesize($filename));
Header("Content-Type: application/octet-stream");
Header("Content-Disposition: attachment; filename=".$filename);
readfile($filename);
?>

PHP implementation of file download

PHP realizes File downloadingHow to issue

php uses curl to implement ftpFile downloadingfunction

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