如何搭建Node.js服务器

const http = require("http");
// 创建服务器实例
const app = http.createServer((req, res) => {
    // 设置响应头，指定内容类型和编码
    res.setHeader("Content-Type", "text/html;charset=utf-8");
    // 根据请求路径返回不同内容
    switch (req.url) {
        case "/":
            res.end("欢迎访问主页！");
            break;
        case "/about":
            res.end("这是关于页面！");
            break;
        default:
            res.statusCode = 404;
            res.end("404 - 页面未找到");
    }
});
// 监听端口并启动服务器
app.listen(5000, () => {
    console.log("服务器已启动！监听在 http://localhost:5000");
});
// 添加错误处理
app.on("error", (error) => {
    console.error(`服务器启动失败: ${error.message}`);
});    

const http = require("http");
const fs = require("fs").promises;
const path = require("path");
// 定义静态资源目录
const STATIC_DIR = path.join(__dirname, "static");
// 内容类型映射表
const CONTENT_TYPES = {
    ".html": "text/html",
    ".css": "text/css",
    ".js": "text/javascript",
    ".json": "application/json",
    ".png": "image/png",
    ".jpg": "image/jpeg",
    ".gif": "image/gif",
    ".svg": "image/svg+xml",
    ".txt": "text/plain"
};
const app = http.createServer(async (req, res) => {
    try {
        // 构建文件路径
        let filePath = path.join(STATIC_DIR, req.url === "/" ? "index.html" : req.url);
        // 检查文件是否存在
        await fs.access(filePath);
        // 获取文件状态
        const stat = await fs.stat(filePath);
        if (stat.isDirectory()) {
            // 如果是目录，尝试默认文件
            filePath = path.join(filePath, "index.html");
            await fs.access(filePath);
        }
        // 获取文件扩展名并确定内容类型
        const extname = path.extname(filePath);
        const contentType = CONTENT_TYPES[extname] || "application/octet-stream";
        // 设置响应头并发送文件内容
        res.setHeader("Content-Type", contentType);
        const fileContent = await fs.readFile(filePath);
        res.end(fileContent);
    } catch (error) {
        // 处理错误
        res.statusCode = 404;
        res.end("404 - 文件未找到");
    }
});
app.listen(3000, () => {
    console.log("服务器监听在 http://localhost:3000");
});    

const http = require("http");
const url = require("url");
const qs = require("querystring");
const app = http.createServer((req, res) => {
    res.setHeader("Content-Type", "text/html;charset=utf-8");
    // 解析URL和查询参数
    const parsedUrl = url.parse(req.url, true);
    const pathname = parsedUrl.pathname;
    const query = parsedUrl.query;
    if (pathname === "/") {
        // 返回表单页面
        const formHtml = `
            <form method="GET" action="/api">
                <input type="text" name="username" placeholder="用户名">
                <input type="password" name="password" placeholder="密码">
                <button type="submit">提交</button>
            </form>
        `;
        res.end(formHtml);
    } else if (pathname === "/api") {
        // 处理GET请求参数
        res.end(`收到GET请求，参数：${JSON.stringify(query)}`);
    } else {
        res.statusCode = 404;
        res.end("404 - 页面未找到");
    }
});
app.listen(8888, () => {
    console.log("服务器已启动！地址为: http://localhost:8888");
});    

const http = require("http");
const qs = require("querystring");
const app = http.createServer((req, res) => {
    res.setHeader("Content-Type", "text/html;charset=utf-8");
    if (req.url === "/") {
        // 返回表单页面
        const formHtml = `
            <form method="POST" action="/api">
                <input type="text" name="username" placeholder="用户名">
                <input type="password" name="password" placeholder="密码">
                <button type="submit">提交</button>
            </form>
        `;
        res.end(formHtml);
    } else if (req.url === "/api" && req.method === "POST") {
        // 处理POST请求
        let body = "";
        // 监听data事件，收集数据块
        req.on("data", (chunk) => {
            body += chunk.toString();
        });
        // 监听end事件，数据接收完成
        req.on("end", () => {
            // 解析表单数据
            const formData = qs.parse(body);
            // 返回处理结果
            res.end(`收到POST请求，参数：${JSON.stringify(formData)}`);
        });
    } else {
        res.statusCode = 404;
        res.end("404 - 页面未找到");
    }
});
app.listen(8888, () => {
    console.log("服务器已启动！地址为: http://localhost:8888");
});