Node.js中net模块详解

Node.js 中 net 模块 API 详解

Node.js 的 net 模块提供了基于 TCP/IP 的网络功能，用于创建 TCP 服务器和客户端。以下是 net 模块的所有 API 详解：

1. 创建 TCP 服务器

const net = require('net');// 1. 基本服务器
const server = net.createServer((socket) => {console.log('客户端已连接');socket.on('data', (data) => {console.log('收到数据:', data.toString());socket.write('服务器已收到数据');});socket.on('end', () => {console.log('客户端已断开连接');});socket.on('error', (err) => {console.error('Socket 错误:', err);});
});server.listen(3000, '127.0.0.1', () => {console.log('服务器运行在 127.0.0.1:3000');
});// 2. 使用 Server 类
const server2 = new net.Server((socket) => {console.log('客户端已连接');
});server2.listen(3001);// 3. 处理连接事件
server.on('connection', (socket) => {console.log('新连接建立');// 设置超时socket.setTimeout(60000); // 60 秒// 设置保活socket.setKeepAlive(true, 60000);// 设置缓冲区大小socket.setNoDelay(true);
});// 4. 错误处理
server.on('error', (err) => {console.error('服务器错误:', err);
});// 5. 关闭服务器
server.close(() => {console.log('服务器已关闭');
});

2. 服务器方法

// 1. 启动服务器
server.listen(3000, '127.0.0.1', () => {console.log('服务器运行在 127.0.0.1:3000');
});// 2. 关闭服务器
server.close(() => {console.log('服务器已关闭');
});// 3. 获取服务器地址信息
const address = server.address();
console.log('服务器地址:', address);
// { address: '127.0.0.1', family: 'IPv4', port: 3000 }// 4. 获取最大连接数
const maxConnections = server.maxConnections;
console.log('最大连接数:', maxConnections);// 5. 设置最大连接数
server.maxConnections = 100;// 6. 获取当前连接数
const connections = server.connections;
console.log('当前连接数:', connections);

3. Socket 对象

// 1. Socket 属性
server.on('connection', (socket) => {console.log('远程地址:', socket.remoteAddress);console.log('远程端口:', socket.remotePort);console.log('本地地址:', socket.localAddress);console.log('本地端口:', socket.localPort);console.log('字节读取:', socket.bytesRead);console.log('字节写入:', socket.bytesWritten);console.log('超时设置:', socket.timeout);console.log('保活设置:', socket.keepAlive);console.log('保活初始延迟:', socket.keepAliveInitialDelay);console.log('无延迟设置:', socket.noDelay);console.log('可写状态:', socket.writable);console.log('可读状态:', socket.readable);console.log('已销毁:', socket.destroyed);
});// 2. Socket 事件
server.on('connection', (socket) => {// 数据事件socket.on('data', (data) => {console.log('收到数据:', data.toString());});// 结束事件socket.on('end', () => {console.log('连接结束');});// 关闭事件socket.on('close', (hadError) => {console.log('连接关闭, 是否有错误:', hadError);});// 错误事件socket.on('error', (err) => {console.error('Socket 错误:', err);});// 超时事件socket.on('timeout', () => {console.log('连接超时');});// 可写事件socket.on('drain', () => {console.log('缓冲区已清空');});// 查找事件socket.on('lookup', (err, address, family, host) => {console.log('DNS 查找结果:', address, family, host);});// 准备事件socket.on('ready', () => {console.log('Socket 已准备就绪');});
});// 3. Socket 方法
server.on('connection', (socket) => {// 写入数据socket.write('Hello Client\n');// 结束写入socket.end();// 暂停读取socket.pause();// 恢复读取socket.resume();// 设置超时socket.setTimeout(60000);// 设置保活socket.setKeepAlive(true, 60000);// 设置无延迟socket.setNoDelay(true);// 获取地址信息const address = socket.address();console.log('Socket 地址:', address);// 销毁 Socketsocket.destroy();
});

4. 创建 TCP 客户端

// 1. 基本客户端
const client = new net.Socket();client.connect(3000, '127.0.0.1', () => {console.log('已连接到服务器');client.write('Hello Server');
});client.on('data', (data) => {console.log('收到数据:', data.toString());
});client.on('end', () => {console.log('与服务器断开连接');
});client.on('error', (err) => {console.error('客户端错误:', err);
});// 2. 使用 createConnection
const client2 = net.createConnection(3000, '127.0.0.1', () => {console.log('已连接到服务器');client2.write('Hello Server');
});// 3. 使用 Unix 域套接字
const unixClient = net.createConnection('/tmp/socket.sock', () => {console.log('已连接到 Unix 域套接字');
});// 4. 使用选项对象
const client3 = net.createConnection({port: 3000,host: '127.0.0.1',timeout: 5000,keepAlive: true,keepAliveInitialDelay: 10000,noDelay: true
}, () => {console.log('已连接到服务器');
});

5. 客户端事件

// 1. 连接事件
client.on('connect', () => {console.log('已连接到服务器');
});// 2. 数据事件
client.on('data', (data) => {console.log('收到数据:', data.toString());
});// 3. 结束事件
client.on('end', () => {console.log('与服务器断开连接');
});// 4. 关闭事件
client.on('close', (hadError) => {console.log('连接关闭, 是否有错误:', hadError);
});// 5. 错误事件
client.on('error', (err) => {console.error('客户端错误:', err);
});// 6. 超时事件
client.on('timeout', () => {console.log('连接超时');
});// 7. 可写事件
client.on('drain', () => {console.log('缓冲区已清空');
});// 8. 查找事件
client.on('lookup', (err, address, family, host) => {console.log('DNS 查找结果:', address, family, host);
});// 9. 准备事件
client.on('ready', () => {console.log('Socket 已准备就绪');
});

6. 客户端方法

// 1. 连接到服务器
client.connect(3000, '127.0.0.1', () => {console.log('已连接到服务器');
});// 2. 写入数据
client.write('Hello Server\n');// 3. 结束连接
client.end();// 4. 销毁连接
client.destroy();// 5. 暂停读取
client.pause();// 6. 恢复读取
client.resume();// 7. 设置超时
client.setTimeout(5000);// 8. 设置保活
client.setKeepAlive(true, 10000);// 9. 设置无延迟
client.setNoDelay(true);// 10. 获取地址信息
const address = client.address();
console.log('客户端地址:', address);

7. 网络工具函数

// 1. 检查是否为 IP 地址
const isIP = net.isIP('192.168.1.1');
console.log('是否为 IP 地址:', isIP); // 4 (IPv4) 或 6 (IPv6) 或 0 (不是 IP)// 2. 检查是否为 IPv4 地址
const isIPv4 = net.isIPv4('192.168.1.1');
console.log('是否为 IPv4 地址:', isIPv4); // true 或 false// 3. 检查是否为 IPv6 地址
const isIPv6 = net.isIPv6('2001:db8::1');
console.log('是否为 IPv6 地址:', isIPv6); // true 或 false// 4. 获取本地 IP 地址
const os = require('os');
const interfaces = os.networkInterfaces();
console.log('网络接口:', interfaces);

8. 实际应用示例

// 1. 回显服务器
const echoServer = net.createServer((socket) => {console.log('客户端已连接');socket.on('data', (data) => {console.log('收到数据:', data.toString());socket.write(data); // 回显数据});socket.on('end', () => {console.log('客户端已断开连接');});
});echoServer.listen(3000, '127.0.0.1');// 2. 聊天服务器
const chatServer = net.createServer();
const clients = [];chatServer.on('connection', (socket) => {console.log('新客户端连接');clients.push(socket);socket.write('欢迎加入聊天室!\n');socket.on('data', (data) => {const message = data.toString().trim();console.log('收到消息:', message);// 广播消息给所有客户端clients.forEach(client => {if (client !== socket) {client.write(`客户端 ${socket.remotePort} 说: ${message}\n`);}});});socket.on('end', () => {console.log('客户端断开连接');const index = clients.indexOf(socket);if (index !== -1) {clients.splice(index, 1);}});
});chatServer.listen(3001, '127.0.0.1');// 3. 端口扫描器
function scanPort(host, port) {return new Promise((resolve) => {const socket = new net.Socket();socket.setTimeout(1000);socket.on('connect', () => {console.log(`端口 ${port} 开放`);socket.destroy();resolve(true);});socket.on('timeout', () => {socket.destroy();resolve(false);});socket.on('error', () => {socket.destroy();resolve(false);});socket.connect(port, host);});
}async function scanPorts(host, startPort, endPort) {console.log(`开始扫描主机 ${host} 的端口 ${startPort}-${endPort}`);for (let port = startPort; port <= endPort; port++) {const isOpen = await scanPort(host, port);if (isOpen) {console.log(`端口 ${port} 开放`);}}console.log('扫描完成');
}// scanPorts('127.0.0.1', 1, 1024);

9. 高级功能

// 1. 多路复用服务器
const multiplexServer = net.createServer();
const channels = {};multiplexServer.on('connection', (socket) => {console.log('新连接建立');socket.on('data', (data) => {const message = JSON.parse(data.toString());if (message.type === 'register') {// 注册通道channels[message.channel] = socket;socket.channel = message.channel;socket.write(JSON.stringify({ type: 'registered', channel: message.channel }) + '\n');} else if (message.type === 'message') {// 转发消息const targetChannel = channels[message.target];if (targetChannel) {targetChannel.write(JSON.stringify({type: 'message',from: socket.channel,data: message.data}) + '\n');}}});socket.on('end', () => {if (socket.channel) {delete channels[socket.channel];}});
});multiplexServer.listen(3002, '127.0.0.1');// 2. 负载均衡器
const backendServers = [{ host: '127.0.0.1', port: 3003 },{ host: '127.0.0.1', port: 3004 },{ host: '127.0.0.1', port: 3005 }
];let currentServer = 0;const loadBalancer = net.createServer((clientSocket) => {const server = backendServers[currentServer];currentServer = (currentServer + 1) % backendServers.length;console.log(`将客户端连接到后端服务器 ${server.host}:${server.port}`);const serverSocket = net.createConnection(server.port, server.host, () => {clientSocket.write('已连接到后端服务器\n');});clientSocket.pipe(serverSocket);serverSocket.pipe(clientSocket);clientSocket.on('error', (err) => {console.error('客户端错误:', err);});serverSocket.on('error', (err) => {console.error('服务器错误:', err);});clientSocket.on('end', () => {serverSocket.end();});serverSocket.on('end', () => {clientSocket.end();});
});loadBalancer.listen(3000, '127.0.0.1');

10. 性能优化

// 1. 使用连接池
class ConnectionPool {constructor(host, port, size) {this.host = host;this.port = port;this.size = size;this.pool = [];this.available = [];}async initialize() {for (let i = 0; i < this.size; i++) {const socket = await this.createConnection();this.pool.push(socket);this.available.push(socket);}}createConnection() {return new Promise((resolve, reject) => {const socket = new net.Socket();socket.connect(this.port, this.host, () => {resolve(socket);});socket.on('error', (err) => {reject(err);});});}acquire() {if (this.available.length === 0) {return null;}return this.available.pop();}release(socket) {if (this.pool.includes(socket)) {this.available.push(socket);}}
}// 2. 使用缓冲区
const bufferServer = net.createServer((socket) => {let buffer = Buffer.alloc(0);socket.on('data', (chunk) => {buffer = Buffer.concat([buffer, chunk]);// 处理完整消息while (buffer.length >= 4) {const messageLength = buffer.readUInt32BE(0);if (buffer.length >= messageLength + 4) {const message = buffer.slice(4, messageLength + 4);buffer = buffer.slice(messageLength + 4);// 处理消息console.log('收到消息:', message.toString());socket.write(Buffer.concat([Buffer.from([0, 0, 0, 4]), // 4 字节长度Buffer.from('OK\n')]));} else {break;}}});
});bufferServer.listen(3006, '127.0.0.1');