以下是一个完整的 Node.js 实现 MySQL 数据库增删改查、前端上传文件和下载文件、前端在线播放视频的示例代码：
后端代码（app.js）：
const express = require('express');
const mysql = require('mysql');
const multer = require('multer');
const app = express();
const upload = multer({ dest: 'uploads/' });
const connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'password',
database: 'database_name'
});
connection.connect((err) => {
if (err) throw err;
console.log('Connected to MySQL database!');
});
app.use(express.static('public'));
app.get('/api/users', (req, res) => {
const sql = 'SELECT * FROM users';
connection.query(sql, (err, results) => {
if (err) throw err;
res.json(results);
});
});
app.post('/api/users', (req, res) => {
const { name, email } = req.body;
const sql = `INSERT INTO users (name, email) VALUES ('${name}', '${email}')`;
connection.query(sql, (err, result) => {
if (err) throw err;
res.json({ message: 'User added successfully!', id: result.insertId });
});
});
app.put('/api/users/:id', (req, res) => {
const { name, email } = req.body;
const id = req.params.id;
const sql = `UPDATE users SET name='${name}', email='${email}' WHERE id=${id}`;
connection.query(sql, (err, result) => {
if (err) throw err;
res.json({ message: 'User updated successfully!', id: id });
});
});
app.delete('/api/users/:id', (req, res) => {
const id = req.params.id;
const sql = `DELETE FROM users WHERE id=${id}`;
connection.query(sql, (err, result) => {
if (err) throw err;
res.json({ message: 'User deleted successfully!', id: id });
});
});
app.post('/api/upload', upload.single('file'), (req, res) => {
console.log(req.file);
res.json({ message: 'File uploaded successfully!' });
});
app.get('/api/download/:filename', (req, res) => {
const filename = req.params.filename;
res.download(`public/${filename}`);
});
app.get('/api/video/:filename', (req, res) => {
const filename = req.params.filename;
res.sendFile(`public/${filename}`);
});
app.listen(3000, () => {
console.log('Server started on port 3000!');
});前端代码：
<!DOCTYPE html>
<html>
<head>
<title>Node.js MySQL File Upload and Download Example</title>
</head>
<body>
<h1>Node.js MySQL File Upload and Download Example</h1>
<h2>Users</h2>
<table>
<thead>
<tr>
<th>ID</th>
<th>Name</th>
<th>Email</th>
<th>Actions</th>
</tr>
</thead>
<tbody id="users-table-body">
</tbody>
</table>
<h2>Add User</h2>
<form>
<label for="name-input">Name:</label>
<input type="text" id="name-input" name="name"><br><br>
<label for="email-input">Email:</label>
<input type="email" id="email-input" name="email"><br><br>
<button type="submit" onclick="addUser()">Add User</button>
</form>
<h2>Upload File</h2>
<form>
<input type="file" id="file-input">
<button type="submit" onclick="uploadFile()">Upload</button>
</form>
<h2>Download File</h2>
<a href="/api/download/file.txt" download>Download</a>
<h2>Play Video</h2>
<video src="/api/video/video.mp4" controls></video>
<script>
function getUsers() {
fetch('/api/users')
.then(response => response.json())
.then(data => {
const usersTableBody = document.getElementById('users-table-body');
usersTableBody.innerHTML = '';
data.forEach(user => {
const tr = document.createElement('tr');
const idTd = document.createElement('td');
idTd.textContent = user.id;
const nameTd = document.createElement('td');
nameTd.textContent = user.name;
const emailTd = document.createElement('td');
emailTd.textContent = user.email;
const actionsTd = document.createElement('td');
const editButton = document.createElement('button');
editButton.textContent = 'Edit';
editButton.onclick = () => editUser(user.id, user.name, user.email);
const deleteButton = document.createElement('button');
deleteButton.textContent = 'Delete';
deleteButton.onclick = () => deleteUser(user.id);
actionsTd.appendChild(editButton);
actionsTd.appendChild(deleteButton);
tr.appendChild(idTd);
tr.appendChild(nameTd);
tr.appendChild(emailTd);
tr.appendChild(actionsTd);
usersTableBody.appendChild(tr);
});
})
.catch(error => console.error(error));
}
function addUser() {
const nameInput = document.getElementById('name-input');
const emailInput = document.getElementById('email-input');
const name = nameInput.value;
const email = emailInput.value;
fetch('/api/users', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({ name, email })
})
.then(response => response.json())
.then(data => {
console.log(data);
getUsers();
})
.catch(error => console.error(error));
}
function editUser(id, name, email) {
const newName = prompt('Enter new name:', name);
const newEmail = prompt('Enter new email:', email);
fetch(`/api/users/${id}`, {
method: 'PUT',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({ name: newName, email: newEmail })
})
.then(response => response.json())
.then(data => {
console.log(data);
getUsers();
})
.catch(error => console.error(error));
}
function deleteUser(id) {
fetch(`/api/users/${id}`, {
method: 'DELETE'
})
.then(response => response.json())
.then(data => {
console.log(data);
getUsers();
})
.catch(error => console.error(error));
}
function uploadFile() {
const fileInput = document.getElementById('file-input');
const file = fileInput.files[0];
const formData = new FormData();
formData.append('file', file);
fetch('/api/upload', {
method: 'POST',
body: formData
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error));
}
getUsers();
</script>
</body>
</html>注意：在使用前请将 database_name 替换为您的 MySQL 数据库名称，将 password 替换为您的 MySQL 数据库密码，将 file.txt 替换为您要下载的文件名，将 video.mp4 替换为您要播放的视频文件名。另外，为了使示例代码正常工作，您需要在项目根目录下创建一个名为 public 的文件夹，并在其中添加一个名为 video.mp4 的视频文件。