主文件功能拆分

backend/middleware/backendInjector.js

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+/**
+ * 后端实例注入中间件
+ * 将PixivBackend实例注入到请求对象中，供后续中间件和路由处理器使用
+ */
+
+function backendInjector(backend) {
+  return (req, res, next) => {
+    req.backend = backend;
+    next();
+  };
+}
+
+module.exports = { backendInjector };

backend/middleware/bodyParser.js

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+/**
+ * Body Parser中间件
+ * 处理JSON和URL编码的请求体
+ */
+const express = require('express');
+
+function bodyParserMiddleware() {
+  return [
+    // JSON 解析中间件
+    express.json({ limit: '20mb' }),
+    // URL编码解析中间件
+    express.urlencoded({ extended: true, limit: '20mb' })
+  ];
+}
+
+module.exports = { bodyParserMiddleware };

backend/middleware/cors.js

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+/**
+ * CORS中间件配置
+ */
+const cors = require('cors');
+
+function corsMiddleware() {
+  return cors({
+    origin: process.env.FRONTEND_URL || true, // 允许所有来源，或者通过环境变量指定
+    credentials: true,
+  });
+}
+
+module.exports = { corsMiddleware };

backend/middleware/logger.js

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+/**
+ * 日志中间件
+ */
+const { defaultLogger } = require('../utils/logger');
+
+// 创建logger实例
+const logger = defaultLogger.child('API');
+
+/**
+ * 自定义日志中间件
+ */
+function loggerMiddleware(req, res, next) {
+  // 过滤掉静态资源请求和图片代理请求
+  const isStaticResource =
+    req.path.startsWith('/assets/') ||
+    req.path.startsWith('/downloads/') ||
+    req.path.includes('.js') ||
+    req.path.includes('.css') ||
+    req.path.includes('.ico') ||
+    req.path.includes('.png') ||
+    req.path.includes('.jpg') ||
+    req.path.includes('.jpeg') ||
+    req.path.includes('.gif') ||
+    req.path.includes('.svg') ||
+    req.path.includes('.woff') ||
+    req.path.includes('.woff2') ||
+    req.path.includes('.ttf') ||
+    req.path.includes('.eot');
+
+  // 过滤掉图片代理请求
+  const isImageProxy = req.path === '/api/proxy/image';
+
+  // 过滤掉下载任务状态查询请求
+  const isDownloadTasksQuery = 
+    req.path === '/api/download/tasks' ||
+    req.path === '/api/download/tasks/active' ||
+    req.path === '/api/download/tasks/summary' ||
+    req.path === '/api/download/tasks/changes' ||
+    req.path === '/api/download/tasks/completed';
+
+  // 过滤掉仓库预览请求（图片预览）
+  const isRepositoryPreview = req.path === '/api/repository/preview';
+
+  // 过滤掉健康检查请求
+  const isHealthCheck = req.path === '/health';
+
+  // 只记录重要的API请求，排除静态资源、图片代理、下载任务查询、仓库预览和健康检查
+  if (!isStaticResource && !isImageProxy && !isDownloadTasksQuery && !isRepositoryPreview && !isHealthCheck) {
+    const start = Date.now();
+
+    // 原始响应结束方法
+    const originalEnd = res.end;
+
+    // 重写响应结束方法以获取响应时间
+    res.end = function (chunk, encoding) {
+      const duration = Date.now() - start;
+      const statusCode = res.statusCode;
+      const method = req.method;
+      const url = req.originalUrl;
+
+      // 根据状态码选择图标
+      let statusIcon;
+      if (statusCode >= 200 && statusCode < 300) {
+        statusIcon = '✅';
+      } else if (statusCode >= 300 && statusCode < 400) {
+        statusIcon = '🔄';
+      } else if (statusCode >= 400 && statusCode < 500) {
+        statusIcon = '⚠️';
+      } else {
+        statusIcon = '❌';
+      }
+
+      // 根据请求类型选择图标
+      let methodIcon;
+      switch (method) {
+        case 'GET':
+          methodIcon = '📥';
+          break;
+        case 'POST':
+          methodIcon = '📤';
+          break;
+        case 'PUT':
+          methodIcon = '🔄';
+          break;
+        case 'DELETE':
+          methodIcon = '🗑️';
+          break;
+        case 'PATCH':
+          methodIcon = '🔧';
+          break;
+        default:
+          methodIcon = '❓';
+      }
+      
+      // 输出日志
+      logger.info(`${statusIcon} ${methodIcon} ${method} ${url} ${statusCode} ${duration}ms`);
+
+      // 调用原始的end方法
+      originalEnd.call(this, chunk, encoding);
+    };
+  }
+
+  next();
+}
+
+module.exports = { loggerMiddleware };

backend/middleware/staticFiles.js

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+/**
+ * 静态文件服务中间件
+ */
+const express = require('express');
+const path = require('path');
+
+function staticFilesMiddleware() {
+  return [
+    // 下载文件静态服务
+    express.static(path.join(__dirname, '../../downloads')),
+    
+    // 前端静态文件服务
+    express.static(path.join(__dirname, '../../ui/dist'))
+  ];
+}
+
+module.exports = { staticFilesMiddleware };