spring + react

different files.jsx

App.jsx:

import {useState} from 'react'
import './App.css'

function App() {
    const [formData, setFormData] = useState({
        name: '',
        email: '',
        phone: '',
        subject: '',
        message: ''
    })
    const [response, setResponse] = useState('')
    const [loading, setLoading] = useState(false)

    const handleChange = (e) => {
        setFormData({
            ...formData,
            [e.target.name]: e.target.value
        })
    }

    const handleSubmit = async (e) => {
        e.preventDefault()
        setLoading(true)
        setResponse('')

        try {
            const res = await fetch('http://localhost:8080/api/submit', {
                method: 'POST',
                headers: {
                    'Content-Type': 'application/json',
                },
                body: JSON.stringify(formData),
            })

            if (res.ok) {
                const message = await res.text()
                setResponse(message)
                setFormData({
                    name: '',
                    email: '',
                    phone: '',
                    subject: '',
                    message: ''
                })
            } else {
                throw new Error('Помилка сервера')
            }
        } catch (error) {
            setResponse('Помилка: ' + error.message)
        } finally {
            setLoading(false)
        }
    }

    return (
        <div className="app-container">
            <div className="form-card">
                <h1 className="form-title">Контактна форма</h1>
                <form onSubmit={handleSubmit} className="form">
                    <div className="input-group">
                        <label htmlFor="name" className="label">Ім'я</label>
                        <input
                            type="text"
                            id="name"
                            name="name"
                            value={formData.name}
                            onChange={handleChange}
                            required
                            className="input"
                            disabled={loading}
                        />
                    </div>
                    <div className="input-group">
                        <label htmlFor="email" className="label">Email</label>
                        <input
                            type="email"
                            id="email"
                            name="email"
                            value={formData.email}
                            onChange={handleChange}
                            required
                            className="input"
                            disabled={loading}
                        />
                    </div>
                    <div className="input-group">
                        <label htmlFor="phone" className="label">Телефон</label>
                        <input
                            type="tel"
                            id="phone"
                            name="phone"
                            value={formData.phone}
                            onChange={handleChange}
                            className="input"
                            disabled={loading}
                        />
                    </div>
                    <div className="input-group">
                        <label htmlFor="subject" className="label">Тема</label>
                        <input
                            type="text"
                            id="subject"
                            name="subject"
                            value={formData.subject}
                            onChange={handleChange}
                            required
                            className="input"
                            disabled={loading}
                        />
                    </div>
                    <div className="input-group">
                        <label htmlFor="message" className="label">Повідомлення</label>
                        <textarea
                            id="message"
                            name="message"
                            value={formData.message}
                            onChange={handleChange}
                            required
                            rows="5"
                            className="textarea"
                            disabled={loading}
                        />
                    </div>
                    <button type="submit" className={`submit-btn ${loading ? 'disabled' : ''}`} disabled={loading}>
                        {loading ? 'Відправка...' : 'Відправити'}
                    </button>
                    {response && (
                        <div className={`response ${response.includes('Помилка') ? 'error' : 'success'}`}>
                            {response}
                        </div>
                    )}
                </form>
            </div>
        </div>
    )
}

export default App

=================================================================================================================================

App.css: (файл index.css має бути пустим!)

:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --success-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --error-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
    --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --card-bg: rgba(255, 255, 255, 0.95);
    --border-color: #e1e5e9;
    --text-primary: #333;
    --text-secondary: #555;
    --shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 25px 50px rgba(0, 0, 0, 0.15);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.6;
    color: var(--text-primary);
}

.app-container {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-gradient);
    padding: 20px;
    position: relative;
    overflow: hidden;
}

.app-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000"><defs><radialGradient id="a" cx="50%" cy="50%" r="50%"><stop offset="0%" stop-color="rgba(255,255,255,0.1)"/><stop offset="100%" stop-color="rgba(255,255,255,0)"/></radialGradient></defs><circle cx="200" cy="200" r="100" fill="url(%23a)"/><circle cx="800" cy="300" r="150" fill="url(%23a)"/><circle cx="400" cy="800" r="120" fill="url(%23a)"/></svg>');
    pointer-events: none;
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% {
        transform: translateY(0px) rotate(0deg);
    }
    50% {
        transform: translateY(-20px) rotate(180deg);
    }
}

.form-card {
    background: var(--card-bg);
    backdrop-filter: blur(20px);
    border-radius: 24px;
    padding: 48px 40px;
    width: 100%;
    max-width: 480px;
    box-shadow: var(--shadow);
    border: 1px solid rgba(255, 255, 255, 0.2);
    position: relative;
    z-index: 1;
    animation: slideUp 0.6s ease-out;
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.form-title {
    text-align: center;
    color: var(--text-primary);
    margin-bottom: 36px;
    font-size: 28px;
    font-weight: 700;
    letter-spacing: -0.5px;
    position: relative;
}

.form-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--primary-gradient);
    border-radius: 2px;
}

.form {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.input-group {
    display: flex;
    flex-direction: column;
}

.label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-secondary);
    font-size: 14px;
    font-weight: 500;
    letter-spacing: 0.5px;
    transition: var(--transition);
}

.input,
.textarea {
    width: 100%;
    padding: 14px 18px;
    border: 2px solid var(--border-color);
    border-radius: 16px;
    font-size: 16px;
    font-family: inherit;
    background: rgba(255, 255, 255, 0.8);
    transition: var(--transition);
    outline: none;
    resize: vertical;
}

.input:focus,
.textarea:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 4px rgba(102, 126, 234, 0.1);
    background: white;
    transform: translateY(-1px);
}

.textarea {
    min-height: 120px;
    font-family: inherit;
}

.submit-btn {
    width: 100%;
    padding: 16px;
    background: var(--primary-gradient);
    color: white;
    border: none;
    border-radius: 16px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    margin-top: 8px;
    position: relative;
    overflow: hidden;
}

.submit-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: -100%;
    width: 100%;
    height: 100%;
    background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
    transition: left 0.5s;
}

.submit-btn:hover:not(.disabled)::before {
    left: 100%;
}

.submit-btn:hover:not(.disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-hover);
}

.submit-btn.disabled {
    opacity: 0.7;
    cursor: not-allowed;
    transform: none;
}

.response {
    padding: 14px 18px;
    border-radius: 16px;
    text-align: center;
    font-size: 14px;
    font-weight: 500;
    margin-top: 16px;
    animation: fadeIn 0.4s ease-out;
    border: 1px solid transparent;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: scale(0.95);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.response.success {
    background: var(--success-gradient);
    color: #0a6c00;
    border-color: rgba(79, 172, 254, 0.3);
}

.response.error {
    background: var(--error-gradient);
    color: #721c24;
    border-color: rgba(250, 112, 154, 0.3);
}

@media (max-width: 480px) {
    .form-card {
        padding: 32px 24px;
        margin: 10px;
    }

    .form-title {
        font-size: 24px;
        margin-bottom: 28px;
    }

    .input,
    .textarea {
        padding: 12px 16px;
    }
}

=================================================================================================================================

ReactApplication.java:

package com.sunmeat.react;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.CrossOrigin;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.Map;

@SpringBootApplication
public class ReactApplication {
	public static void main(String[] args) {
		SpringApplication.run(ReactApplication.class, args);
	}
}

@RestController
@CrossOrigin(origins = "http://localhost:5173")
class SubmitController {
	@PostMapping("/api/submit")
	public String submitData(@RequestBody Map<String, String> data) {
		System.out.println("Отримано дані з форми (з React на 5173):");
		data.forEach((key, value) -> System.out.println(key + ": " + value));
		return "Дані отримано на сервері! (Перевірте консоль)";
	}
}