php 常用

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PHP加密解密PHP加密和解密函数可以用来加密一些有用的字符串存放在数据库里，并且通过可逆解密字符串，该函数使用了base64和MD5加密和解密。function encryptDecrypt($key, $string, $decrypt){    if($decrypt){        $decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, md5($key), base64_decode($string), MCRYPT_MODE_CBC, md5(md5($key))), "12");        return $decrypted;    }else{        $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_RIJNDAEL_256, md5($key), $string, MCRYPT_MODE_CBC, md5(md5($key))));        return $encrypted;    }}//以下是将字符串“Helloweba欢迎您”分别加密和解密//加密：echo encryptDecrypt('password', 'Helloweba欢迎您',0);//解密：echo encryptDecrypt('password', 'z0JAx4qMwcF+db5TNbp/xwdUM84snRsXvvpXuaCa4Bk=',1);PHP生成随机字符串当我们需要生成一个随机名字，临时密码等字符串时可以用到下面的函数：function generateRandomString($length = 10) {    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';    $randomString = '';    for ($i = 0; $i < $length; $i++) {        $randomString .= $characters[rand(0, strlen($characters) - 1)];    }    return $randomString;}echo generateRandomString(20);

PHP获取文件扩展名（后缀）以下函数可以快速获取文件的扩展名即后缀。function getExtension($filename){    $myext = substr($filename, strrpos($filename, '.'));    return str_replace('.','',$myext);}$filename = '我的文档.doc';echo getExtension($filename);PHP获取文件大小并格式化以下使用的函数可以获取文件的大小，并且转换成便于阅读的KB，MB等格式。function formatSize($size) {    $sizes = array(" Bytes", " KB", " MB", " GB", " TB", " PB", " EB", " ZB", " YB");    if ($size == 0) {        return('n/a');    } else {        return (round($size/pow(1024, ($i = floor(log($size, 1024)))), 2) . $sizes[$i]);    }}$thefile = filesize('test_file.mp3');echo formatSize($thefile);PHP替换标签字符有时我们需要将字符串、模板标签替换成指定的内容，可以用到下面的函数：function stringParser($string,$replacer){    $result = str_replace(array_keys($replacer), array_values($replacer),$string);    return $result;}$string = 'The {b}anchor text{/b} is the {b}actual word{/b} or words used {br}to describe the link {br}itself';$replace_array = array('{b}' => '<b>','{/b}' => '</b>','{br}' => '<br />');echo stringParser($string,$replace_array);PHP列出目录下的文件名如果你想列出目录下的所有文件，使用以下代码即可：function listDirFiles($DirPath){    if($dir = opendir($DirPath)){        while(($file = readdir($dir))!== false){            if(!is_dir($DirPath.$file))            {                echo "filename: $file<br />";            }        }    }}listDirFiles('home/some_folder/');PHP获取当前页面URL以下函数可以获取当前页面的URL，不管是http还是https。function curPageURL() {    $pageURL = 'http';    if (!empty($_SERVER['HTTPS'])) {$pageURL .= "s";}    $pageURL .= "://";    if ($_SERVER["SERVER_PORT"] != "80") {        $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];    } else {        $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];    }    return $pageURL;}echo curPageURL();PHP强制下载文件有时我们不想让浏览器直接打开文件，如PDF文件，而是要直接下载文件，那么以下函数可以强制下载文件，函数中使用了application/octet-stream头类型。function download($filename){    if ((isset($filename))&&(file_exists($filename))){        header("Content-length: ".filesize($filename));        header('Content-Type: application/octet-stream');        header('Content-Disposition: attachment; filename="' . $filename . '"');        readfile("$filename");    } else {        echo "Looks like file does not exist!";    }}download('/down/test_45f73e852.zip');or$filename = $_GET['file']; //Get the fileid from the URL// Query the file ID$query = sprintf("SELECT * FROM tableName WHERE id = '%s'",mysql_real_escape_string($filename));$sql = mysql_query($query);if(mysql_num_rows($sql) > 0){    $row = mysql_fetch_array($sql);// Set some headers    header("Pragma: public");    header("Expires: 0");    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");    header("Content-Type: application/force-download");    header("Content-Type: application/octet-stream");    header("Content-Type: application/download");    header("Content-Disposition: attachment; filename=".basename($row['FileName']).";");    header("Content-Transfer-Encoding: binary");    header("Content-Length: ".filesize($row['FileName']));    @readfile($row['FileName']);    exit(0);}else{    header("Location: /");    exit;}PHP截取字符串长度我们经常会遇到需要截取字符串(含中文汉字)长度的情况，比如标题显示不能超过多少字符，超出的长度用...表示，以下函数可以满足你的需求。/* Utf-8、gb2312都支持的汉字截取函数 cut_str(字符串, 截取长度, 开始长度, 编码); 编码默认为 utf-8 开始长度默认为 0*/function cutStr($string, $sublen, $start = 0, $code = 'UTF-8'){    if($code == 'UTF-8'){        $pa = "/[x01-x7f]|[xc2-xdf][x80-xbf]|xe0[xa0-xbf][x80-xbf]|[xe1-xef][x80-xbf][x80-xbf]|xf0[x90-xbf][x80-xbf][x80-xbf]|[xf1-xf7][x80-xbf][x80-xbf][x80-xbf]/";        preg_match_all($pa, $string, $t_string);        if(count($t_string[0]) - $start > $sublen) return join('', array_slice($t_string[0], $start, $sublen))."...";        return join('', array_slice($t_string[0], $start, $sublen));    }else{        $start = $start*2;        $sublen = $sublen*2;        $strlen = strlen($string);        $tmpstr = '';        for($i=0; $i<$strlen; $i++){            if($i>=$start && $i<($start+$sublen)){                if(ord(substr($string, $i, 1))>129){                    $tmpstr.= substr($string, $i, 2);                }else{                    $tmpstr.= substr($string, $i, 1);                }            }            if(ord(substr($string, $i, 1))>129) $i++;        }        if(strlen($tmpstr)<$strlen ) $tmpstr.= "...";        return $tmpstr;    }}$str = "jQuery插件实现的加载图片和页面效果";echo cutStr($str,16);PHP获取客户端真实IP我们经常要用数据库记录用户的IP，以下代码可以获取客户端真实的IP：//获取用户真实IPfunction getIp() {    if (getenv("HTTP_CLIENT_IP") && strcasecmp(getenv("HTTP_CLIENT_IP"), "unknown"))        $ip = getenv("HTTP_CLIENT_IP");    else        if (getenv("HTTP_X_FORWARDED_FOR") && strcasecmp(getenv("HTTP_X_FORWARDED_FOR"), "unknown"))            $ip = getenv("HTTP_X_FORWARDED_FOR");        else            if (getenv("REMOTE_ADDR") && strcasecmp(getenv("REMOTE_ADDR"), "unknown"))                $ip = getenv("REMOTE_ADDR");            else                if (isset ($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] && strcasecmp($_SERVER['REMOTE_ADDR'], "unknown"))                    $ip = $_SERVER['REMOTE_ADDR'];                else                    $ip = "unknown";    return ($ip);}echo getIp();PHP防止SQL注入我们在查询数据库时，出于安全考虑，需要过滤一些非法字符防止SQL恶意注入，请看以下函数：function injCheck($sql_str) {    if (is_array($sql_str))    {        foreach ($sql_str as $key => $val)        {            $sql_str[$key] = injCheck($val);        }    }else{        $sql_str = (string)$sql_str;        if (get_magic_quotes_gpc())        {            $output = stripslashes($output);        }        $check = preg_match('/select|insert|update|delete|/*|*|../|./|union|into|load_file|outfile/', $sql_str);        if ($check) {            echo '非法字符！！';            exit;        } else {            return $sql_str;        }    }}echo injCheck('1 or 1=1');PHP页面提示与跳转我们在进行表单操作时，有时为了友好需要提示用户操作结果，并跳转到相关页面，请看以下函数：function message($msgTitle,$message,$jumpUrl){    $str = '<!DOCTYPE HTML>';    $str .= '<html>';    $str .= '<head>';    $str .= '<meta charset="utf-8">';    $str .= '<title>页面提示</title>';    $str .= '<style type="text/css">';    $str .= '*{margin:0; padding:0}a{color:#369; text-decoration:none;}a:hover{text-decoration:underline}body{height:100%; font:12px/18px Tahoma, Arial,  sans-serif; color:#424242; background:#fff}.message{width:450px; height:120px; margin:16% auto; border:1px solid #99b1c4; background:#ecf7fb}.message h3{height:28px; line-height:28px; background:#2c91c6; text-align:center; color:#fff; font-size:14px}.msg_txt{padding:10px; margin-top:8px}.msg_txt h4{line-height:26px; font-size:14px}.msg_txt h4.red{color:#f30}.msg_txt p{line-height:22px}';    $str .= '</style>';    $str .= '</head>';    $str .= '<body>';    $str .= '<div class="message">';    $str .= '<h3>'.$msgTitle.'</h3>';    $str .= '<div class="msg_txt">';    $str .= '<h4 class="red">'.$message.'</h4>';    $str .= '<p>系统将在 <span style="color:blue;font-weight:bold">3</span> 秒后自动跳转,如果不想等待,直接点击 <a href="{$jumpUrl}">这里</a> 跳转</p>';    $str .= "<script>setTimeout('location.replace('".$jumpUrl."')',2000)</script>";    $str .= '</div>';    $str .= '</div>';    $str .= '</body>';    $str .= '</html>';    echo $str;}message('操作提示','操作成功！','http://www.xxx.xxx/');随机颜色生成器function randomColor() {    $str = '#';    for($i = 0 ; $i < 6 ; $i++) {        $randNum = rand(0 , 15);        switch ($randNum) {            case 10: $randNum = 'A'; break;            case 11: $randNum = 'B'; break;            case 12: $randNum = 'C'; break;            case 13: $randNum = 'D'; break;            case 14: $randNum = 'E'; break;            case 15: $randNum = 'F'; break;        }        $str .= $randNum;    }    return $str;}$color = randomColor();
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