PHP开发笔记系列(四)-文件操作
??? 对于一般的web应用程序,数据会保存在数据库表中,但是文件操作也是必须的,例如文件的读取、写入等,典型的应用场景是考试报名,当系统启动时,自动读取“报名须知”的内容到内存中,然后再需要时显示到页面当中。这次本文《PHP开发笔记系列(四)-文件操作》 将研究一下PHP中的文件操作。
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1. 读取文件到数组(file)
??? file()函数可以将文件按行读取到一个字符串数组中,后续程序可以通过遍历这个字符串数组来做处理。
file:file.php url:http://localhost:88/file/file.php <?php $file = file(basename(__FILE__)); $lines = count($file); for($i=0; $i<$lines; $i++){ $color = ($i%2==0) ? 'red' : 'white'; echo '<div style="background-color: '.$color.'">'; echo $i.':'.htmlspecialchars($file[$i]); echo '</div>'; } ?>?
2. 读取文件到字符串(file_get_contents)
??? file_get_contents()函数可以将文件中的所有内容读取到一个字符串变量中,后续程序可以将这个字符串中的内容显示在页面,或者写入到新文件当中。
file:file_get_contents.php url:http://localhost:88/file/readfile.php <?php $file = file_get_contents('file.html'); $file = strip_tags($file); echo '<form><textarea rows=12 cols=80>'.htmlspecialchars($file).'</textarea></form>'; ?>?
3. 读取文件到屏幕(readfile)
??? readfile()函数直接读取文件内容并回显到屏幕,上传或下载时也会用到这个函数。
file:readfile.php url:http://localhost:88/file/readfile.php <?php readfile('file.html'); ?>
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??? 上面的方法只能全部或按照新行符读取文件中的内容,读到数组或字符串或屏幕中,然后如果需要更加灵活的读取文件内容或写文件内容,就需要用到文件句柄了,类似于C语言当中的文件读写函数。
4. 一次读取整个文件内容(fread、filesize)
??? 对于文件的大小相对比较小的文件,可以一次将整个文件的内容读取到内存当中。步骤是,1)fopen打开新文件,并指定使用模式,2)使用fread按照指定的长度读取文件内容,3)fclose关闭句柄。
file:fread.php url:http://localhost:88/file/fread.php <?php $location = 'file.html'; $file = fopen($location, "rb"); $fileContent = fread($file, filesize($location)); fclose($file); echo $fileContent; ?>?
5. 分次读取整个文件的内容(fgets、feof)
??? fgets函数可以分片获取文件的中内容,feof可以判断文件是否已经读取到末尾。
file:fgets.php url:http://localhost:88/file/fgets.php <?php $location = 'file.html'; $fp = fopen($location, 'rb'); while(!feof($fp)){ $chunk = fgets($fp); echo $chunk; } fclose($fp); ?>?
6. 一次读取(file_get_contents),一次写入(file_put_contents)
??? 有时候对于小文件读取和写入,可以方便的使用file_get_contents()和file_put_contents()方法进行写入,无需创建文件句柄。
file:readOnce_writeOnce.php url:http://localhost:88/file/readOnce_writeOnce.php <?php $source = 'file.html'; $destination1 = 'readOnce_writeOnce.html'; // 一次读取,一次写入 $sourceContent = file_get_contents($source); file_put_contents($destination1, $sourceContent); ?>
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7. 分行读取,分行写入(fwrite)
??? 对于大文件的读取和写入,如果一次load到内容,很有可能导致内存溢出或web服务器宕机,因此需要采用逐行读取逐行写入。可以使用file()行数将源文件读取到一个字符串数组中,然后通过fwrite逐行写入目标文件,当然,需要使用fopen打开句柄,写入结束后使用fclose关闭句柄。
file:multiRead_multiWrite.php url:http://localhost:88/file/multiRead_multiWrite.php <?php $source = 'file.html'; $destination2 = 'multiRead_multiWrite.html'; $lines = file($source); $fp = fopen($destination2, 'w'); foreach ($lines as $line) { fwrite($fp, $line); } fclose($fp); ?>?
8. 其他文件处理函数
file:other.php url:http://localhost:88/file/other.php <?php $fileName = basename(__FILE__); $dirPath = './'; // file_exists()返回1 或 0 echo $fileName.': '.file_exists($fileName).'<br/>'; // is_file()返回1 或 0 echo $fileName.' is '.is_file($fileName)?'file':'directory'.'!'.'<br/>'; // is_readable()返回1 或 0 echo $fileName.' readable:'.is_readable($fileName).'<br/>'; // is_writable()返回1 或 0 echo $fileName.' writable:'.is_writable($fileName).'<br/>'; echo $fileName.' created at:'.filemtime($fileName).'<br/>'; echo $fileName.' created at:'.fileatime($fileName).'<br/>'; echo $fileName.' size:'.filesize($fileName).'<br/>'; ?>
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9. 目录读取(opendire、readdir、closedir)
??? 第一种方法,使用opendir、readdir、closedir函数进行目录的打开、读取、关闭,类似于文件的fopen、fread、fclose,代码如下:
file:dir.php url:http://localhost:88/file/dir.php <?php $location = './'; $dp = opendir($location); while ($entry = readdir($dp)){ if(is_dir($entry)) { echo '[DIR] '.$entry. '<br/>'; }elseif (is_file($entry)) { echo '[FILE] '.$entry. '<br/>'; } } closedir($dp); ?>
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??? 第二种方法,采用php提供的面向对象的dir类,通过传入一个目录路径来构造一个dir实例,再通过实例的read方法进行目录读取,代码如下:
file:dir-class.php url:http://localhost:88/file/dir-class.php <?php $location = './'; $dir = dir($location); while ($entry = $dir->read()){ if(is_dir($entry)) { echo '[DIR] '.$entry. '<br/>'; }elseif (is_file($entry)) { echo '[FILE] '.$entry. '<br/>'; } } closedir($dp); ?>?
10. 文件拷贝(copy)
file:copy.php url:http://localhost:88/file/copy.php <?php $source = 'file.html'; $dest = 'file-copy.html'; copy($source, $dest); ?>
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11. 文件移动、重命名(rename)
<?php $source = 'file-copy.html'; $dest = 'file-copy-1.html'; rename($source, $dest); ?>
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??? 本文地址:http://ryan-d.iteye.com/blog/1543374

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