express的bodyParser无法解析?

输出req.files为undefined,req.body为{},请问这是为什么呢?谢谢

var express = require('express');
var bodyParser = require('body-parser');
var fs =require('fs');
var server = express();
server.use(bodyParser.json()).use(bodyParser.urlencoded({ extended: true }));
server.get('/', function (req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});
    fs.createReadStream(__dirname + '/static.html').pipe(res);
});
server.post('/upload', function (req, res) {
    console.log(req.files);
    console.log(req.body);
});
server.listen(3003);
<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="file1" multiple="multiple" />
    <input type="submit" />
</form>
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