Refactor exam information workflow

src/http/responses.mjs

@@ -0,0 +1,46 @@
+export function sendJson(response, status, payload, headers = {}) {
+  response.writeHead(status, { 'Content-Type': 'application/json; charset=utf-8', 'Cache-Control': 'no-store', ...headers });
+  response.end(JSON.stringify(payload));
+}
+
+export function sendError(response, status, message, details) {
+  sendJson(response, status, { ok: false, message, ...(details ? { details } : {}) });
+}
+
+export async function readJson(request) {
+  const chunks = [];
+  let size = 0;
+  for await (const chunk of request) {
+    size += chunk.length;
+    if (size > 1024 * 1024) throw Object.assign(new Error('请求内容过大'), { status: 413 });
+    chunks.push(chunk);
+  }
+  if (!chunks.length) return {};
+  try {
+    return JSON.parse(Buffer.concat(chunks).toString('utf8'));
+  } catch {
+    throw Object.assign(new Error('请求数据格式不正确'), { status: 400 });
+  }
+}
+
+export async function readBodyBuffer(request, maxBytes = 12 * 1024 * 1024) {
+  const chunks = [];
+  let size = 0;
+  for await (const chunk of request) {
+    size += chunk.length;
+    if (size > maxBytes) throw Object.assign(new Error('Excel 文件不能超过 12 MB'), { status: 413 });
+    chunks.push(chunk);
+  }
+  if (!chunks.length) throw Object.assign(new Error('请选择要导入的 Excel 文件'), { status: 400 });
+  return Buffer.concat(chunks);
+}
+
+export function sendWorkbook(response, buffer, filename) {
+  response.writeHead(200, {
+    'Content-Type': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
+    'Content-Disposition': `attachment; filename*=UTF-8''${encodeURIComponent(filename)}`,
+    'Content-Length': buffer.length,
+    'Cache-Control': 'no-store'
+  });
+  response.end(buffer);
+}