php – 如何正确迭代一个大的json文件

它们有几种不同的风格：类似SAX的推送解析器和拉解析器. XML reader models: SAX versus XML pull parser概述了差异.

推分析器

这是使用salsify/json-streaming-parser的快速示例.

当它浏览文件时,我们将跟踪summonerId,championId和state.它都是基于事件的 – 您不会通过顺序解析器获得随机访问权限,因此您必须自己跟踪事物.每当totalSessionsPlayed出现时,它都会回显summonerId,championId和totalSessionsPlayed.

data.json

这是一个用于演示目的的配对json文件.

[
    {
        "_id": "53b29644aafd413977b23b7e","summonerId": 24570940,"stats": {
            "110": {
                "totalSessionsPlayed": 3,"totalSessionsLost": 2,"totalSessionsWon": 1
            },"112": {
                "totalSessionsPlayed": 45,"totalSessionsWon": 1
            }
        }
    },{
        "_id": "asdfasdfasdf","summonerId": 555555,"stats": {
            "42": {
                "totalSessionsPlayed": 65,"88": {
                "totalSessionsPlayed": 99,"totalSessionsWon": 1
            }
        }
    }
]

例：

class ListMatchUps extends JsonStreamingParserListenerIdleListener
{

    private $key;
    private $summonerId;
    private $championId;
    private $inStats;

    public function start_document()
    {
        $this->key        = null;
        $this->summonerId = null;
        $this->championId = null;
        $this->inStats    = false;
    }

    public function start_object()
    {
        if ($this->key === 'stats') {
            $this->inStats = true;
        } else if ($this->inStats) {
            $this->championId = $this->key;
        }
    }

    public function end_object()
    {
        if ($this->championId !== null) {
            $this->championId = null;
        } else if ($this->inStats) {
            $this->inStats = false;
        } else {
            $this->summonerId = null;
        }
    }

    public function key($key)
    {
        $this->key = $key;
    }

    public function value($value)
    {
        switch ($this->key) {
            case 'summonerId':
                $this->summonerId = $value;
                break;
            case 'totalSessionsPlayed':
                echo "{$this->summonerId},{$this->championId},$valuen";
                break;
        }
    }
}

$stream = fopen('data.json','r');
$listener = new ListMatchUps();
try {
    $parser = new JsonStreamingParser_Parser($stream,$listener);
    $parser->parse();
} catch (Exception $e) {
    fclose($stream);
    throw $e;
}

输出：

24570940,110,3
24570940,112,45
555555,42,65
555555,88,99

拉解析器

这是使用我最近编写的解析器,pcrov/jsonreader(需要PHP 7.)

与上面相同的data.json.

例：

use pcrovJsonReaderJsonReader;

$reader = new JsonReader();
$reader->open("data.json");

while($reader->read("summonerId")) {
    $summonerId = $reader->value();
    $reader->next("stats");
    foreach($reader->value() as $championId => $stats) {
        echo "$summonerId,$championId,{$stats['totalSessionsPlayed']}n";
    }
}
$reader->close();

输出：

24570940,99