Node.js和Tomcat是两种常用的服务器端技术。虽然它们都用于构建网络应用程序，但在许多方面存在显著差异。本文将介绍Node.js和Tomcat之间的主要区别，并提供一些示例代码来帮助读者更好地理解这些差异。

javascript
// 引入依赖
const express = require('express');
const http = require('http');
const socketIO = require('socket.io');
// 创建Express应用程序
const app = express();
const server = http.createServer(app);
const io = socketIO(server);
// 处理客户端连接
io.on('connection', (socket) => {
  console.log('客户端已连接');
  // 处理客户端发送的消息
  socket.on('message', (data) => {
    console.log('接收到消息:', data);
    // 广播消息给所有客户端
    io.emit('message', data);
  });
  // 处理客户端断开连接
  socket.on('disconnect', () => {
    console.log('客户端已断开连接');
  });
});
// 启动服务器
server.listen(3000, () => {
  console.log('服务器已启动，监听端口3000');
});

java
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet {
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("");
    out.println("");
    out.println("");
    out.println("
Hello World!
");
    out.println("");
  }
}