feat: Add Core API demonstration module

index.js

@@ -5,6 +5,7 @@ const { exec } = require('child_process');
 const LargeFileHandler = require('./src/largeFile');
 const xmlJsonHandler = require('./src/xmlJson');
 const performanceMonitor = require('./src/performance');
+const CoreApiDemo = require('./src/coreApiDemo');
 
 const app = express();
 const PORT = 7860;
@@ -68,6 +69,12 @@ async function runJsonDemo() {
     }
 }
 
+// Feature 4: Core APIs Demo
+async function runCoreApiDemo() {
+    const coreDemo = new CoreApiDemo(DATA_DIR);
+    await coreDemo.run();
+}
+
 function logMemoryUsage() {
     const used = process.memoryUsage();
     console.log('Memory Usage:');
@@ -92,9 +99,11 @@ app.get('/', (req, res) => {
                     button { padding: 15px; font-size: 16px; cursor: pointer; background: #007bff; color: white; border: none; border-radius: 5px; transition: background 0.3s; font-weight: bold; }
                     button:hover { background: #0056b3; }
                     button:disabled { background: #ccc; cursor: not-allowed; }
+                    .btn-core { background: #6610f2; }
+                    .btn-core:hover { background: #520dc2; }
                     .btn-system { background: #28a745; }
                     .btn-system:hover { background: #218838; }
-                    .btn-clear { background: #6c757d; grid-column: span 2; }
+                    .btn-clear { background: #6c757d; }
                     .btn-clear:hover { background: #5a6268; }
                     #output { background: #1e1e1e; color: #d4d4d4; padding: 20px; border-radius: 5px; font-family: "Menlo", "Monaco", "Courier New", monospace; height: 500px; overflow-y: auto; white-space: pre-wrap; font-size: 14px; line-height: 1.5; border: 1px solid #333; }
                     .status { margin-top: 10px; font-style: italic; color: #666; }
@@ -108,6 +117,7 @@ app.get('/', (req, res) => {
                         <button onclick="runDemo('xml')">🏷️ 2. XML 解析处理</button>
                         <button onclick="runDemo('json')">📦 3. JSON 流式解析</button>
                         <button onclick="getSystemInfo()" class="btn-system">🖥️ 4. 系统信息 (child_process)</button>
+                        <button onclick="runDemo('core-api')" class="btn-core">🛠️ 5. 核心 API 综合演示</button>
                         <button onclick="clearOutput()" class="btn-clear">🗑 清空输出</button>
                     </div>
                     <div id="output">点击上方按钮开始测试...</div>
@@ -251,6 +261,9 @@ app.get('/api/run-demo', async (req, res) => {
             case 'json':
                 await runJsonDemo();
                 break;
+            case 'core-api':
+                await runCoreApiDemo();
+                break;
             default:
                 console.log('未知的任务类型');
         }

src/coreApiDemo.js

@@ -0,0 +1,104 @@
+const fs = require('fs');
+const path = require('path');
+const os = require('os');
+const EventEmitter = require('events');
+const { pipeline } = require('stream');
+const { promisify } = require('util');
+
+const pipelineAsync = promisify(pipeline);
+
+/**
+ * Node.js 核心 API 演示模块
+ * 展示: fs, path, stream, os, events, util
+ */
+class CoreApiDemo extends EventEmitter {
+    constructor(dataDir) {
+        super();
+        this.dataDir = dataDir;
+        this.demoFile = path.join(dataDir, 'core_demo.txt');
+        this.copyFile = path.join(dataDir, 'core_demo_copy.txt');
+    }
+
+    async run() {
+        console.log('--- 开始 Node.js 核心 API 演示 ---');
+
+        try {
+            // 1. Path 模块演示
+            this.demoPath();
+
+            // 2. OS 模块演示
+            this.demoOs();
+
+            // 3. Events 模块演示
+            this.demoEvents();
+
+            // 4. FS & Stream 模块演示
+            await this.demoFsAndStream();
+
+        } catch (err) {
+            console.error('核心 API 演示出错:', err);
+        }
+        
+        console.log('--- 核心 API 演示结束 ---');
+    }
+
+    demoPath() {
+        console.log('\n[Path 模块]');
+        console.log(`__dirname: ${__dirname}`);
+        console.log(`文件名 (basename): ${path.basename(this.demoFile)}`);
+        console.log(`扩展名 (extname): ${path.extname(this.demoFile)}`);
+        console.log(`解析路径 (parse):`, path.parse(this.demoFile));
+    }
+
+    demoOs() {
+        console.log('\n[OS 模块]');
+        console.log(`平台: ${os.platform()} (${os.arch()})`);
+        console.log(`主机名: ${os.hostname()}`);
+        console.log(`总内存: ${(os.totalmem() / 1024 / 1024 / 1024).toFixed(2)} GB`);
+        console.log(`空闲内存: ${(os.freemem() / 1024 / 1024 / 1024).toFixed(2)} GB`);
+        console.log(`CPU核数: ${os.cpus().length}`);
+    }
+
+    demoEvents() {
+        console.log('\n[Events 模块]');
+        console.log('注册自定义事件 "hello"...');
+        
+        // 监听一次性事件
+        this.once('hello', (data) => {
+            console.log(`触发了 "hello" 事件，数据: ${JSON.stringify(data)}`);
+        });
+
+        // 触发事件
+        this.emit('hello', { msg: 'Node.js is cool!', timestamp: Date.now() });
+    }
+
+    async demoFsAndStream() {
+        console.log('\n[FS & Stream 模块]');
+        
+        // FS: 写入文件
+        const content = 'Hello Node.js Core APIs!\nThis is a test file for streams.\n' + new Date().toISOString();
+        console.log(`写入文件: ${this.demoFile}`);
+        fs.writeFileSync(this.demoFile, content);
+
+        // FS: 获取文件状态
+        const stats = fs.statSync(this.demoFile);
+        console.log(`文件大小: ${stats.size} bytes`);
+        console.log(`创建时间: ${stats.birthtime}`);
+
+        // Stream: 流式复制文件
+        console.log(`使用 Stream Pipeline 复制文件到: ${this.copyFile}`);
+        
+        await pipelineAsync(
+            fs.createReadStream(this.demoFile),
+            fs.createWriteStream(this.copyFile)
+        );
+        
+        console.log('文件复制完成 (Stream pipeline)');
+
+        // FS: 读取复制后的文件验证
+        const copiedContent = fs.readFileSync(this.copyFile, 'utf8');
+        console.log('读取复制文件内容前 50 字符:', copiedContent.substring(0, 50).replace(/\n/g, '\\n') + '...');
+    }
+}
+
+module.exports = CoreApiDemo;