在对于字符串的替换上，我们已经学过了不少的方法。但在做练习题的时候，我们会对多个字符串进行替换。从方法的实用性来说，str_replace就非常适合处理多个字符串的替换问题。下面我们就php中str_replace的概念、语法、参数、返回值进行讲解，然后带来替换的实例分享。
<&＃63;php
/**
* 安全过滤函数
*
* @param $string
* @return string
*/
function safe_replace($string) {
$string = str_replace('%20','',$string);
$string = str_replace('%27','',$string);
$string = str_replace('%2527','',$string);
$string = str_replace('*','',$string);
$string = str_replace('"','"',$string);
$string = str_replace("'",'',$string);
$string = str_replace('"','',$string);
$string = str_replace(';','',$string);
$string = str_replace('<','<',$string);
$string = str_replace('>','>',$string);
$string = str_replace("{",'',$string);
$string = str_replace('}','',$string);
$string = str_replace('','',$string);
return $string;
}
&＃63;>
<&＃63;php
/**
* 返回经addslashes处理过的字符串或数组
* @param $string 需要处理的字符串或数组
* @return mixed
*/
function new_addslashes($string) {
if(!is_array($string)) return addslashes($string);
foreach($string as $key => $val) $string[$key] = new_addslashes($val);
return $string;
}
&＃63;>
<&＃63;php
//对请求的字符串进行安全处理
/*
$safestep
0 为不处理，
1 为禁止不安全HTML内容(Javascript等)，
2 完全禁止HTML内容，并替换部份不安全字符串（如：eval(、union、CONCAT(、--、等）
*/
function StringSafe($str, $safestep=-1){
$safestep = ($safestep > -1) &＃63; $safestep : 1;
if($safestep == 1){
$str = preg_replace("#script:#i", "ｓｃｒｉｐｔ：", $str);
$str = preg_replace("#<[/]{0,1}(link|meta|ifr|fra|scr)[^>]*>#isU", '', $str);
$str = preg_replace("#[ ]{1,}#", ' ', $str);
return $str;
}else if($safestep == 2){
$str = addslashes(htmlspecialchars(stripslashes($str)));
$str = preg_replace("#eval#i", 'ｅｖａｌ', $str);
$str = preg_replace("#union#i", 'ｕｎｉｏｎ', $str);
$str = preg_replace("#concat#i", 'ｃｏｎｃａｔ', $str);
$str = preg_replace("#--#", '－－', $str);
$str = preg_replace("#[ ]{1,}#", ' ', $str);
return $str;
}else{
return $str;
}
}
&＃63;>
<&＃63;php
/**
+----------------------------------------------------------
* 输出安全的html，用于过滤危险代码
+----------------------------------------------------------
* @access public
+----------------------------------------------------------
* @param string $text 要处理的字符串
* @param mixed $tags 允许的标签列表，如 table|td|th|td
+----------------------------------------------------------
* @return string
+----------------------------------------------------------
*/
static public function safeHtml($text, $tags = null)
{
$text = trim($text);
//完全过滤注释
$text = preg_replace('//','',$text);
//完全过滤动态代码
$text = preg_replace('/<&＃63;|&＃63;'.'>/','',$text);
//完全过滤js
$text = preg_replace('//','',$text);
$text = str_replace('[','&＃091;',$text);
$text = str_replace(']','&＃093;',$text);
$text = str_replace('|','&＃124;',$text);
//过滤换行符
$text = preg_replace('/ &＃63; /','',$text);
//br
$text = preg_replace('//i','[br]',$text);
$text = preg_replace('/([br]s*){10,}/i','[br]',$text);
//过滤危险的属性，如：过滤on事件lang js
while(preg_match('/(<[^><]+)(lang|on|action|background|codebase|dynsrc|lowsrc)[^><]+/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1],$text);
}
while(preg_match('/(<[^><]+)(window.|Javascript:|js:|about:|file:|document.|vbs:|COOKIE)([^><]*)/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1].$mat[3],$text);
}
if( empty($allowTags) ) { $allowTags = self::$htmlTags['allow']; }
//允许的HTML标签
$text = preg_replace('/<('.$allowTags.')( [^><[]]*)>/i','[12]',$text);
//过滤多余html
if ( empty($banTag) ) { $banTag = self::$htmlTags['ban']; }
$text = preg_replace('/<]*>/i','',$text);
//过滤合法的html标签
while(preg_match('/<([a-z]+)[^><[]]*>[^><]*/i',$text,$mat)){
$text=str_replace($mat[0],str_replace('>',']',str_replace('<','[',$mat[0])),$text);
}
//转换引号
while(preg_match('/([[^[]]*=s*)("|')([^2=[]]+)2([^[]]*])/i',$text,$mat)){
$text=str_replace($mat[0],$mat[1].'|'.$mat[3].'|'.$mat[4],$text);
}
//空属性转换
$text = str_replace('''','||',$text);
$text = str_replace('""','||',$text);
//过滤错误的单个引号
while(preg_match('/[[^[]]*("|')[^[]]*]/i',$text,$mat)){
$text=str_replace($mat[0],str_replace($mat[1],'',$mat[0]),$text);
}
//转换其它所有不合法的 <>
$text = str_replace('<','<',$text);
$text = str_replace('>','>',$text);
$text = str_replace('"','"',$text);
//反转换
$text = str_replace('[','<',$text);
$text = str_replace(']','>',$text);
$text = str_replace('|','"',$text);
//过滤多余空格
$text = str_replace(' ',' ',$text);
return $text;
}
&＃63;>
<&＃63;php
function RemoveXSS($val) {
// remove all non-printable characters. CR(0a) and LF(0b) and TAB(9) are allowed
// this prevents some character re-spacing such as
// note that you have to handle splits with , , and later since they *are* allowed in some // inputs
$val = preg_replace('/([x00-x08,x0b-x0c,x0e-x19])/', '', $val);
// straight replacements, the user should never need these since they're normal characters
// this prevents like )
$search = 'abcdefghijklmnopqrstuvwxyz';
$search .= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
$search .= '1234567890!@#$%^&*()';
$search .= '~`";:&＃63;+/={}[]-_|'';
for ($i = 0; $i 0) {
$pattern .= '(';
$pattern .= '(&＃[xX]0{0,8}([9ab]);)';
$pattern .= '|';
$pattern .= '|(&＃0{0,8}([9|10|13]);)';
$pattern .= ')*';
}
$pattern .= $ra[$i][$j];
}
$pattern .= '/i';
$replacement = substr($ra[$i], 0, 2).''.substr($ra[$i], 2); // add in <> to nerf the tag
$val = preg_replace($pattern, $replacement, $val); // filter out the hex tags
if ($val_before == $val) {
// no replacements were made, so exit the loop
$found = false;
}
}
}
return $val;
}
&＃63;>
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