HTML5 file api读取文件的MD5码工具

时间：2021-06-28 08:09:44

1、工具的用途：用HTML5 file api读取文件的MD5码。MD5码在文件的唯一性识别上有很重要的应用，业内常用MD5进行文件识别、文件秒传、文件安全性检查等；

2、适用性：IE、Chrome皆兼容；

3、缺陷：当上传大文件时，需要较长的时间才能扫描出MD5码；

4、关于引用：其中引用了js文件（spark-md5.js）

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="utf-8">

    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">

    <title>HTML5 read files hash</title>

    <meta name="author" content="Mofei">

    <meta name="viewport" content="width=device-width; initial-scale=1.0;">

    <script src="spark-md5.js" type="text/javascript"></script>

</head>

<body>

    <div>

        <header>

            <h1>HTML5 read files hash</h1>

        </header>

        <div>

            <input type="file" id="file">

            <div id="box"></div>

        </div>

        <footer>

            <p>&copy; Copyright  by Percy(<a href="http://www.cnblogs.com/Percy_Lee/">www.cnblogs.com/Percy_Lee</a>)</p>

        </footer>

    </div>

    <script type="text/javascript">

     document.getElementById("file").addEventListener("change", function () {

        var fileReader = new FileReader(),

            box = document.getElementById('box'),

            blobSlice = File.prototype.mozSlice || File.prototype.webkitSlice || File.prototype.slice,

            file = document.getElementById("file").files[0],

            chunkSize = 2097152,

            chunks = Math.ceil(file.size / chunkSize),

            currentChunk = 0,

            bs = fileReader.readAsBinaryString,

            spark = bs ? new SparkMD5() : new SparkMD5.ArrayBuffer();

        fileReader.onload = function (ee) {

            spark.append(ee.target.result);

            currentChunk++;

            if (currentChunk < chunks) {

                loadNext();

            } else {

                box.innerText = 'MD5:  ' + spark.end();

            }

        }

        function loadNext() {

            var start = currentChunk * chunkSize, end = start + chunkSize >= file.size ? file.size : start + chunkSize;

            if (bs) fileReader.readAsBinaryString(blobSlice.call(file, start, end));

            else fileReader.readAsArrayBuffer(blobSlice.call(file, start, end));

        }

        loadNext();

    });

    </script>

</body>

</html>

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