PHP使用迭代器Iterator读取大容量文本文件

Posted 2022-11-21 SuperAvalon

某度早期php简易面试题，用php处理大容量文件，比如内存只有100m，要处理2G的文本文件，php怎么办？

可以通过fgets函数来逐行读取，然后通过Iterator来实现一个迭代器，方便遍历，

分享下代码：

<?php

class Reader implements Iterator 
    
    private $num;
    
    private $handler;
    
    public function __construct($file)
    
        $this->handler = fopen($file, "r");
    
    
    
    public function __destruct()
    
        fclose($this->handler);
    
    
    public function current()
    
        return fgets($this->handler, 2048);
    
    
    public function next()
    
        $this->num++;
    
    
    public function key()
    
        return $this->num;
    
    
    public function valid()
    
        return !feof($this->handler);
    
    
    public function rewind()
    
        fseek($this->handler, 0);
        
        $this->num = 1;
    


$file = __FILE__;

$reader = new Reader($file);

foreach ($reader as $k => $v) 
    echo $k ."\\t\\t" . $v . "\\r\\n";