添加二维码生成和存储功能，将二维码URL存储到数据库

server.js

@@ -88,10 +88,10 @@ const server = http.createServer(async (req, res) => {
       // 从数据库获取对应会话的最新合格证信息
       let query, params;
       if (sessionId) {
-        query = 'SELECT company as subjectName, phoneNumber as contact, productName, grossWeight as weight, commitBasis as basis, origin, DATE_FORMAT(issueDate, "%Y-%m-%d") as date, signature FROM certificate WHERE sessionId = ? ORDER BY id DESC LIMIT 1';
+        query = 'SELECT company as subjectName, phoneNumber as contact, productName, grossWeight as weight, commitBasis as basis, origin, DATE_FORMAT(issueDate, "%Y-%m-%d") as date, signature, qrCodeUrl FROM certificate WHERE sessionId = ? ORDER BY id DESC LIMIT 1';
         params = [sessionId];
       } else {
-        query = 'SELECT company as subjectName, phoneNumber as contact, productName, grossWeight as weight, commitBasis as basis, origin, DATE_FORMAT(issueDate, "%Y-%m-%d") as date, signature FROM certificate WHERE sessionId IS NULL ORDER BY id DESC LIMIT 1';
+        query = 'SELECT company as subjectName, phoneNumber as contact, productName, grossWeight as weight, commitBasis as basis, origin, DATE_FORMAT(issueDate, "%Y-%m-%d") as date, signature, qrCodeUrl FROM certificate WHERE sessionId IS NULL ORDER BY id DESC LIMIT 1';
         params = [];
       }
       
@@ -184,10 +184,42 @@ const server = http.createServer(async (req, res) => {
             }
           }
           
+          // 生成查看页面的URL，包含会话ID
+          const viewUrl = `http://8.137.125.67:3008/view.html?sessionId=${encodeURIComponent(sessionId)}`;
+          
+          // 生成二维码并上传到OSS
+          let qrCodeUrl = null;
+          try {
+            // 使用Google Charts API生成二维码
+            const qrCodeApiUrl = `https://api.qrserver.com/v1/create-qr-code/?size=300x300&data=${encodeURIComponent(viewUrl)}`;
+            
+            // 下载二维码图片
+            const https = require('https');
+            const qrCodeBuffer = await new Promise((resolve, reject) => {
+              https.get(qrCodeApiUrl, (response) => {
+                const chunks = [];
+                response.on('data', (chunk) => chunks.push(chunk));
+                response.on('end', () => resolve(Buffer.concat(chunks)));
+                response.on('error', reject);
+              }).on('error', reject);
+            });
+            
+            // 生成唯一的文件名
+            const timestamp = Date.now();
+            const qrCodeFilename = `certificate_qrcode_${timestamp}.png`;
+            
+            // 上传到OSS，指定文件夹为certificate/qrcodes
+            qrCodeUrl = await OssUploader.uploadBuffer(qrCodeBuffer, qrCodeFilename, 'certificate/qrcodes', 'image');
+            console.log('二维码上传到OSS成功:', qrCodeUrl);
+          } catch (error) {
+            console.error('上传二维码到OSS失败:', error.message);
+            // 即使上传失败，也继续处理
+          }
+          
           // 插入数据到数据库
           await pool.execute(
-            'INSERT INTO certificate (company, phoneNumber, productName, grossWeight, commitBasis, origin, issueDate, signature, sessionId) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)',
+            'INSERT INTO certificate (company, phoneNumber, productName, grossWeight, commitBasis, origin, issueDate, signature, sessionId, qrCodeUrl) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)',
-            [certificate.subjectName, certificate.contact, certificate.productName, certificate.weight, certificate.basis, certificate.origin, certificate.date, signatureUrl, certificate.sessionId]
+            [certificate.subjectName, certificate.contact, certificate.productName, certificate.weight, certificate.basis, certificate.origin, certificate.date, signatureUrl, certificate.sessionId, qrCodeUrl]
           );
           
           console.log('数据插入数据库成功');
@@ -196,6 +228,7 @@ const server = http.createServer(async (req, res) => {
         const responseCertificate = {
           ...certificate,
           signature: signatureUrl,
+          qrCodeUrl: qrCodeUrl,
           // 格式化日期为YYYY-MM-DD格式
           date: certificate.date.toISOString().split('T')[0]
         };