google-apps-script - 使用什么 Google Apps 脚本方法来获取重定向的 URL？

Question

“www.mysite.com/mySecretKey1”重定向到“www.othersite.com/mySecretKey2”

在 G.AppsScript 中:

  var response = UrlFetchApp.fetch("https://www.mysite.com/mySecretKey1");
  var headerString = response.getAllHeaders().toSource();
  Logger.log(headerString);
  //string 'www.othersite.com.my/SecretKey2' is not present in log.

脚本如何发现它重定向到的 URL 地址(即字符串“www.othersite.com/mySecretKey2”)？

更新:更一般地说，脚本如何从响应中发现URL地址？

Answer 1

阐述answer by Joseph Combs ，这是一个使用递归来跟踪多个重定向的版本，仅返回最终的规范 URL:

function getRedirect(url) {
  var response = UrlFetchApp.fetch(url, {'followRedirects': false, 'muteHttpExceptions': false});
  var redirectUrl = response.getHeaders()['Location']; // undefined if no redirect, so...
  var responseCode = response.getResponseCode();
  if (redirectUrl) {                                   // ...if redirected...
    var nextRedirectUrl = getRedirect(redirectUrl);    // ...it calls itself recursively...
    Logger.log(url + " is redirecting to " + redirectUrl + ". (" + responseCode + ")");
    return nextRedirectUrl;
  }
  else {                                               // ...until it's not
    Logger.log(url + " is canonical. (" + responseCode + ")");
    return url;
  }
}  

function testGetRedirect() {
  Logger.log("Returned: " + getRedirect("http://wikipedia.org"));
}

此日志:

https://www.wikipedia.org/ is canonical. (200)
https://wikipedia.org/ is redirecting to https://www.wikipedia.org/. (301)
http://wikipedia.org is redirecting to https://wikipedia.org/. (301)
Returned: https://www.wikipedia.org/