const http = require('http');
const fs = require('fs');
const filePath = './1.mp4';
const server = http.createServer((req, res) => {
    const range = req.headers.range
    if (range) {
        const stat = fs.statSync(filePath);
        const fileSize = stat.size;
        const rangeList = range.replace("bytes=", "").split('-');
        const bufferSize = 1024 * 1024 * 2;//每次传输的字节数，或设置未为fileSize，让客户端尽可能长的获取字节数
        let startPos = parseInt(rangeList[0], 10);
        let endPos = startPos + bufferSize;
        if (endPos >= fileSize) {
            endPos = fileSize - 1;
        } 
        const ContentLength = endPos - startPos + 1;
        res.setHeader('Accept-Ranges', 'bytes');
        res.setHeader('Content-Range', 'bytes ' + startPos + '-' + endPos + '/' + fileSize);
        res.setHeader('Content-Length', ContentLength);
        if (endPos == fileSize - 1) {
            res.writeHead(206, 'Partial Content', {
                'Content-Type': 'video/mp4',
            });
        } else {
            res.writeHead(206, 'Partial Content', {
                'Content-Type': 'application/octet-stream',
            });
        }
        var fReadStream = fs.createReadStream(filePath, {
            encoding: 'binary',
            bufferSize:bufferSize,
            start:startPos,
            end:endPos
        });
        fReadStream.on('data', function (chunk) {
            res.write(chunk, 'binary');
        });
        fReadStream.on('end', function () {
            res.end();
        });
    } else {
        res.end();
    }
});
server.listen(3001);
console.log('server.listen(3001)')