nodejs 使用DataView写本地二进制文件时读取问题

taojianlong 2022-06-10 原文

最近遇到这个问题很困惑的问题

使用nodejs写了个本地文件

代码如下

function test() {

    let buffer = new ArrayBuffer(8);
    let u8A = new Uint8Array(buffer);
    let dataView = new DataView(u8A.buffer);
    dataView.setInt8(0, 127);
    dataView.setUint16(1, 256, true);
    dataView.setUint16(3, 11, true); //当这里写入的值大于 127时出现问题
    dataView.setUint16(5, 165, true);//当这里写入的值大于127时会溢出（浏览器读取时）
    let url = "test.bin";
    fs.writeFile(url, dataView, { encoding: 'utf-8' }, function (err) {// 'utf8'
        if (err) {
            console.log('写入文件失败 url: ' + url);//+ " text: " + text
            return;
        }
        console.log('===>写入bin文件成功 url: ' + url);
    });
    console.log("=====>OutBin path:" + path + "  buffer.byteLength: " + buffer.byteLength);
    setTimeout(() => {
        fs.readFile("test.bin", {}, (err, buffer) => {

            console.log("=============>load test.bin buffer: " + buffer + " byteLength: " + buffer.byteLength);

            let dv = new DataView(buffer);
            let a = dv.getInt8(0);
            let b = dv.getUint16(1, true);
            let c = dv.getUint16(3, true);
            let d = dv.getUint16(5, true);

            console.log(`a=${a} b=${b} c=${c} d=${d}`);  //本地这里读取这里没问题
        });
    }, 2000);
}
test();

在本地服务起打开index.html时读取生成的该文件时出现溢出问题！！！

<html>

<head>
    <title>www.layabox.com</title>
    <meta charset='utf-8' />
    <meta name='renderer' content='webkit' />
    <meta name='viewport'
        content='width=device-width,initial-scale=1.0,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no' />
    <meta name='apple-mobile-web-app-capable' content='yes' />
    <meta name='full-screen' content='true' />
    <meta name='x5-fullscreen' content='true' />
    <meta name='360-fullscreen' content='true' />
    <meta name='laya' screenorientation='landscape' />
    <meta http-equiv='expires' content='0' />
    <meta http-equiv='X-UA-Compatible' content='IE=edge,chrome=1' />
    <meta http-equiv='expires' content='0' />
    <meta http-equiv='Cache-Control' content='no-siteapp' />
</head>

<body>
    <script type="text/javascript">
        function loadLib(url) {
            var script = document.createElement("script");
            script.async = false;
            script.src = url;
            document.body.appendChild(script);
        }
        var request = new XMLHttpRequest();
        request.open("get", "test.bin");
        request.send(null);
        request.responseType = "arraybuffer";
        request.onload = function () {
            console.log("arraybuffer-----", request.response);

            let dv = new DataView(request.response);

            let a = dv.getInt8(0);
            let b = dv.getUint16(1, true);
            let c = dv.getUint16(3, true);//这里值大于127时会产生溢出
            let d = dv.getUint16(5, true);//这里值大于127时会产生溢出

            console.log(`a=${a} b=${b} c=${c} d=${d}`);
        }
    </script>
</body>

</html>