Php有什么方法可以获得待读取文件的编码方式原理：
使用 mb_detect_encoding() 函数来判断字符串是什么编码的。
注意：要把php.ini中 extension=php_mbstring.dll 前的;号去掉，重启apache就可以了。
我创建三个文件：text1.txt text2.txt text3.txt
分别以ASCII UTF-8 UNICODE 的编码方式保存
php代码如下：
<?php
define (‘UTF32_BIG_ENDIAN_BOM’ , chr(0x00) . chr(0x00) . chr(0xFE) . chr(0xFF));
define (‘UTF32_LITTLE_ENDIAN_BOM’, chr(0xFF) . chr(0xFE) . chr(0x00) . chr(0x00));
define (‘UTF16_BIG_ENDIAN_BOM’ , chr(0xFE) . chr(0xFF));
define (‘UTF16_LITTLE_ENDIAN_BOM’, chr(0xFF) . chr(0xFE));
define (‘UTF8_BOM’, chr(0xEF) . chr(0xBB) . chr(0xBF));
function detect_utf_encoding($text) {
$first2 = substr($text, 0, 2);
$first3 = substr($text, 0, 3);
$first4 = substr($text, 0, 3);
if ($first3 == UTF8_BOM) return ‘UTF-8’;
elseif ($first4 == UTF32_BIG_ENDIAN_BOM) return ‘UTF-32BE’;
elseif ($first4 == UTF32_LITTLE_ENDIAN_BOM) return ‘UTF-32LE’;
elseif ($first2 == UTF16_BIG_ENDIAN_BOM) return ‘UTF-16BE’;
elseif ($first2 == UTF16_LITTLE_ENDIAN_BOM) return ‘UTF-16LE’;
}
function getFileEncoding($str){
$encoding=mb_detect_encoding($str);
if(empty($encoding)){
$encoding=detect_utf_encoding($str);
}
return $encoding;
}
$file = ‘text1.txt’;
echo getFileEncoding(file_get_contents($file)); // 输出ASCII
echo ‘<br />’;
$file = ‘text2.txt’;
echo getFileEncoding(file_get_contents($file)); // 输出UTF-8
echo ‘<br />’;
$file = ‘text3.txt’;
echo getFileEncoding(file_get_contents($file)); // 输出UTF-16LE
echo ‘<br />’;
?>
