[PHP] 读取大文件并显示

使用PHP读取日志文件，当文件比较大的时候，会报内存不足，因此应该部分读取，读取指定的行数的数据

PHP代码：

<?php
class Test{
    //日志路径
    const LOG_PATH="E:\phpServer\Apache\logs\error.log";
    const NGINX_LOG_PATH="E:\phpServer\\nginx\logs\error.log";
    //显示的行数
    const PAGES=50;
    public static function main(){
        header("content-type:text/html;charset=utf-8");

        if(!empty($_GET['action'])){
            self::$_GET['action']();
            exit;
        }
    }

    public static function showApacheLogs(){
        $test=new Test();
        $result=$test->readLogs(self::LOG_PATH,self::PAGES);
        $html="";
        foreach($result as $line){
            if(strpos($line,"error:")){
                $line="<font color='red'>".$line."</font>";
            }
            $html.="<div class='line'>".$line."<div>";
        }
        echo $html;
    }
    public static function showNginxLogs(){
        $test=new Test();
        $result=$test->readLogs(self::NGINX_LOG_PATH,self::PAGES);
        $html="";
        foreach($result as $line){
            if(strpos($line,"error")){
                $line="<font color='red'>".$line."</font>";
            }
            $html.="<div class='line'>".$line."<div>";
        }
        echo $html;
    }
    /**
    * 读取日志
    */
    private function readLogs($filePath,$num=20){
        $fp = fopen($filePath,"r");
        $pos = -2;
        $eof = "";
        $head = false;   //当总行数小于Num时，判断是否到第一行了
        $lines = array();
        while($num>0){
            while($eof != "\n"){
                if(fseek($fp, $pos, SEEK_END)==0){    //fseek成功返回0，失败返回-1
                    $eof = fgetc($fp);
                    $pos--;
                }else{                               //当到达第一行，行首时，设置$pos失败
                    fseek($fp,0,SEEK_SET);
                    $head = true;                   //到达文件头部，开关打开
                    break;
                }  

            }
            array_unshift($lines,fgets($fp));
            if($head){ break; }                 //这一句，只能放上一句后，因为到文件头后，把第一行读取出来再跳出整个循环
            $eof = "";
            $num--;
        }
        fclose($fp);
        return array_reverse($lines);
    }
}
Test::main();
?>
<style type="text/css">
*{
    padding: 0;
    margin: 0;
}
.logsBox{
    margin:5px;
    padding: 5px;
    width: 600px;
    background: #000;
    color:#fff;
    font-size: 13px;
    float: left;
}
.logsBox .line{
    margin: 12px 0;
}
</style>
<div class="logsBox apache">
    <div class="line">日志读取...</div>
</div>
<div class="logsBox nginx">
    <div class="line">日志读取...</div>
</div>
<script type="text/javascript" src="http://apps.bdimg.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
    $(function(){

        function showLogs(api,showClass){
            function readLogs(){
                $.ajax({
                    url:api,
                    type:"get",
                    dataType:"text",
                    success:function(data){
                        $(showClass).html(data);
                    }
                });
            }
            readLogs();
            setInterval(readLogs,5000);
        }
        showLogs("?action=showNginxLogs",".nginx");
        showLogs("?action=showApacheLogs",".apache");
    });
</script>