addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})

async function handleRequest(request) {
  try {
    // 解析 URL 参数
    const url = new URL(request.url)
    const targetUrl = url.searchParams.get('url')
    
    if (!targetUrl) {
      return new Response('Missing url parameter', { status: 400 })
    }
    
    // 验证 URL 格式
    try {
      new URL(targetUrl)...