Question

我正在学习如何在Java 8中使用htmlUnit，我试图将应用程序部署到谷歌应用程序引擎，这将经常刮掉某些网站。我正在Eclipse中开发应用程序，它在本地运行时按预期工作，但是在部署到GAE后，我的应用程序无法再与任何网站建立连接。

 try (final WebClient webClient = new WebClient()) {

      webClient.setCookieManager(new CookieManager() {
          protected int getPort(final java.net.URL url) {
          final int r = super.getPort(url);
          return r != -1 ? r : 80;
          }
          });  

      final HtmlPage page = webClient.getPage("https://www.google.com");
      }

  catch(Exception e){
      System.out.println(e.getMessage());         
  }

错误发生在＆＃34; webClient.getPage（....）＆＃34;

java.net.UnknownHostException: www.google.com

部分堆栈跟踪：

[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>: java.lang.RuntimeException: java.net.UnknownHostException: www.recreation.gov
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.UrlFetchWebConnection.getResponse(UrlFetchWebConnection.java:162)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.loadWebResponseFromWebConnection(WebClient.java:1394)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.loadWebResponse(WebClient.java:1312)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:396)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:317)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:465)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at com.gargoylesoftware.htmlunit.WebClient.getPage(WebClient.java:450)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at pack.HelloAppEngine.doGet(HelloAppEngine.java:49)
[s~permitseacherbpd/20180314t161057.408306947286449649].<stderr>:   at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)

我尝试访问的任何网站都会出现此错误，并且不是htmlUnit独有的，因为我在其他项目之前遇到过此错误。为什么我在部署到应用引擎后无法连接？

Answer 1

我的小测试servlet也开始抛出类似的UnknownHostException。我遇到#63916008链接到注意到的<url-stream-handler> documentation（强调我的）

对于Java 8运行时，默认值为native，这意味着标准Java网络类使用标准Java HTTP（S）传输，如Java 8运行时与Java 7行为中所述。 此设置要求应用启用结算，否则请求会产生以下运行时错误：

的java.net.UnknownHostException
  java.net.SocketTimeoutException
  java.io.IOException的

将appengine-web.xml配置为使用urlfetch，您的问题应该得到解决！

尝试连接到网站时使用GAE应用程序的未知主机异常

1 个答案: