PHP实现的文件操作类及文件下载功能示例

本文实例讲述了PHP实现的文件操作类及文件下载功能。分享给大家供大家参考，具体如下：
文件操作类：

<?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"s try reading it.echo $myfile->read（）;//Then let"s try writing to the file.$myfile->write （"Hello World！"）;//Then, let"s try appending.$myfile->append （"Hello Again！"）;?>

文件下载：

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

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希望本文所述对大家PHP程序设计有所帮助。