Flutter无法连接Express应用，用户数据无法存入MongoDB问题求助

我正尝试通过Node.js和Express，把Flutter端的用户数据存入本地MongoDB，但数据始终无法成功存储。我已经写好了REST API，也在Flutter里调用了接口，但就是没效果。下面是我的代码，麻烦各位帮忙排查下问题！

Express REST API代码 #

const express = require('express');

const mongodb = require('mongodb');

const MongoClient = mongodb.MongoClient;

let database;

async function initDb() {

const client = await MongoClient.connect('mongodb://127.0.0.1:27017');

database = client.db('project');

}

function getDb() {

if(!database) {

throw new Error('Database not connected');

}

return database;

}

const app = express();

app.use(express.json());

app.post('/data', function(req, res, next) {

console.log(req.body);

getDb().collection('userData').insertOne(req.body);

console.log('Data submited');

res.json('Data submited');

});

initDb().then(function() {

app.listen(3000, console.log('Listining to port 3000'));

}).catch(function(error) {

console.log('Connecting to the database failed');

});

Flutter调用API的代码 #

class StoreUserData {

postData() async {

print('Function Called');

try {

var response = http.post(

Uri.parse('http://10.0.2.2:3000/data'),

body: {

'username': user!.displayName,

'email': user!.email,

'uid': user!.uid

},

);

} catch (error) {

print(error);

}

}

}

备注：内容来源于stack exchange，提问作者Mayur Panchal