php 常用自定义方法

主要方法有检测 ajax 请求调整图像尺寸网址字符串转换成超级链接 URL地址预设 http 字符串解压缩 Zip 文件文件 Zip 压缩创建标签云强制性文件下载返回字符串相似程度的百分比截断文字

强制性文件下载

//      1. PHP强制性文件下载
function force_download($file)  
{  
    if ((isset($file))&&(file_exists($file))) {  
        header("Content-length: ".filesize($file));  
        header('Content-Type: application/octet-stream');  
        header('Content-Disposition: attachment; filename="' . $file . '"');  
        readfile("$file");  
    } else {  
        echo "No file selected";  
    }  
}

创建标签云

//　　2. PHP创建标签云
function getCloud( $data = array(), $minFontSize = 12, $maxFontSize = 30 )  
{  
    $minimumCount = min( array_values( $data ) );  
    $maximumCount = max( array_values( $data ) );  
    $spread = $maximumCount - $minimumCount;  
    $cloudHTML = '';  
    $cloudTags = array();   
      
    $spread == 0 && $spread = 1;   
  
    foreach( $data as $tag => $count )  
    {  
        $size = $minFontSize + ( $count - $minimumCount )  * ( $maxFontSize - $minFontSize ) / $spread;  
        $cloudTags[] = '<a style="font-size: ' . floor( $size ) . 'px' . '" href="#" title="\'' . $tag .  
        '\' returned a count of ' . $count . '">' . htmlspecialchars( stripslashes( $tag ) ) . '</a>';  
    }   
      
    return join( "\n", $cloudTags ) . "\n";  
}  

$arr = Array('Actionscript' => 35, 'Adobe' => 22, 'Array' => 44, 'Background' => 43,  'Blur' => 18, 'Canvas' => 33, 'Class' => 15, 'Color Palette' => 11, 'Crop' => 42,  
'Delimiter' => 13, 'Depth' => 34, 'Design' => 8, 'Encode' => 12, 'Encryption' => 30,  'Extract' => 28, 'Filters' => 42);  

echo getCloud($arr, 12, 36);

寻找两个字符串的相似性返回相似程度的百分比


//　　3. PHP寻找两个字符串的相似性  返回相似程度的百分比
//    PHP 提供了一个极少使用的 similar_text 函数，但此函数非常有用，用于比较两个字符串并返回相似程度的百分比。
similar_text($string1, $string2, $percent);  
//$percent will have the percentage of similarity

使用 Gravatar 通用头像

//　　4. PHP在应用程序中使用 Gravatar 通用头像
//　　随着 WordPress 越来越普及，Gravatar 也随之流行。由于 Gravatar 提供了易于使用的 API，将其纳入应用程序也变得十分方便。
function show_gravatar($email, $size, $default, $rating)  
{  
    echo '<！！！！img src="http://www.gravatar.com/avatar.php?gravatar_id='.md5($email).  
    '&default='.$default.'&size='.$size.'&rating='.$rating.'" width="'.$size.'px" height="'.$size.'px" />';  
}

在字符断点处截断文字

//　　5. PHP在字符断点处截断文字
//　　所谓断字 (word break)，即一个单词可在转行时断开的地方。这一函数将在断字处截断字符串。
// Original PHP code by Chirp Internet: www.chirp.com.au  
// Please acknowledge use of this code by including this header. 
function myTruncate($string, $limit, $break=".", $pad="...") {  
    // return with no change if string is shorter than $limit  
    if(strlen($string) <= $limit)  
    return $string;   
    // is $break present between $limit and the end of the string?  
    if(false !== ($breakpoint = strpos($string, $break, $limit))) {  
        if($breakpoint < strlen($string) - 1) {  
            $string = substr($string, 0, $breakpoint) . $pad;  
        }  
    }  
    return $string;  
}  
 
$short_string=myTruncate($long_string, 100, ' ');

文件 Zip 压缩

//　　6. PHP文件 Zip 压缩
function create_zip($files = array(),$destination = '',$overwrite = false) {  
    //if the zip file already exists and overwrite is false, return false  
    if(file_exists($destination) && !$overwrite) { return false; }  
    //vars  
    $valid_files = array();  
    //if files were passed in...  
    if(is_array($files)) {  
    //cycle through each file  
        foreach($files as $file) {  
        //make sure the file exists  
            if(file_exists($file)) {  
                $valid_files[] = $file;  
            }  
        }  
    }  
    //if we have good files...  
    if(count($valid_files)) {  
        //create the archive  
        $zip = new ZipArchive();  
        if($zip->open($destination,$overwrite ? ZIPARCHIVE::OVERWRITE : ZIPARCHIVE::CREATE) !== true) {  
            return false;  
        }  
        //add the files  
        foreach($valid_files as $file) {  
            $zip->addFile($file,$file);  
        }  
        //debug  
        //echo 'The zip archive contains ',$zip->numFiles,' files with a status of ',$zip->status;   
      
        //close the zip -- done!  
        $zip->close();   
      
        //check to make sure the file exists  
        return file_exists($destination);  
    }  
    else  
    {  
        return false;  
    }  
}  
 
$files=array('file1.jpg', 'file2.jpg', 'file3.gif');  
create_zip($files, 'myzipfile.zip', true);

解压缩 Zip 文件

//　　7. PHP解压缩 Zip 文件
function unzip_file($file, $destination){  
    // create object  
    $zip = new ZipArchive() ;  
    // open archive  
    if ($zip->open($file) !== TRUE) {  
        die ('Could not open archive');  
    }  
    // extract contents to destination directory  
    $zip->extractTo($destination);  
    // close archive  
    $zip->close();  
    echo 'Archive extracted to directory';  
}

URL 地址预设 http 字符串

//　　8. PHP为 URL 地址预设 http 字符串
if (!preg_match("/^(http|ftp):/", $_POST['url'])) {  
   $_POST['url'] = 'http://'.$_POST['url'];  
}

URL 和 E-mail 地址字符串转换为可点击的超级链接。

//　　9. PHP将网址字符串转换成超级链接
function makeClickableLinks($text) {  
    $text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&//=]+)', '<a href="\1">\1</a>', $text);  
    $text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)','\1<a href="http://\2">\2</a>', $text);  
    $text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',  '<a href="mailto:\1">\1</a>', $text);   
    return $text;  
}

后台重新定义图像尺寸方法为阻塞方式需要许多时间此代码将有助于了解缩略图的逻辑。

//　　10. PHP调整图像尺寸
function resize_image($filename, $tmpname, $xmax, $ymax) {  
    $ext = explode(".", $filename);  
    $ext = $ext[count($ext)-1];    
  
    if($ext == "jpg" || $ext == "jpeg")  
        $im = imagecreatefromjpeg($tmpname);  
    elseif($ext == "png")  
        $im = imagecreatefrompng($tmpname);  
    elseif($ext == "gif")  
        $im = imagecreatefromgif($tmpname);    
  
    $x = imagesx($im);  
    $y = imagesy($im);    
    
    if($x <= $xmax && $y <= $ymax)  
        return $im;    
    if($x >= $y) {  
        $newx = $xmax;  
        $newy = $newx * $y / $x;  
    } else {  
        $newy = $ymax;  
        $newx = $x / $y * $newy;  
    }    
    $im2 = imagecreatetruecolor($newx, $newy);  
    imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);  
    return $im2;  
}

检测 ajax 请求主要判断的是头部信息 HTTP_X_REQUESTED_WITH == xmlhttprequest

//　　11. PHP检测 ajax 请求

if( !emptyempty($_SERVER['HTTP_X_REQUESTED_WITH'])  && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){  
    //If AJAX Request Then  
}else{  
    //something else  
}

php 常用自定义方法

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