我应该如何返回数据

from flask import Flask, jsonify

app = Flask(__name__)

@app.route('/data')
def get_data():
    data = {'key': 'value'}
    return jsonify(data)

if __name__ == '__main__':
    app.run()

from django.http import JsonResponse

def get_data(request):
    data = {'key': 'value'}
    return JsonResponse(data)

const express = require('express');
const app = express();

app.get('/data', (req, res) => {
    const data = { key: 'value' };
    res.json(data);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class DataController {

    @GetMapping("/data")
    public Map<String, String> getData() {
        Map<String, String> data = new HashMap<>();
        data.put("key", "value");
        return data;
    }
}

<?php
header('Content-Type: application/json');

$data = ['key' => 'value'];
echo json_encode($data);
?>

class DataController < ApplicationController
  def index
    @data = { key: 'value' }
    render json: @data
  end
end