java - UnknownHostException java

Question

我的程序在一段时间内完美运行，但之后出现错误

java.net.UnknownHostException: www.sears.com
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:666)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1534)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1439)
at extractData.ReviewsSearch.getJsonResponse(ReviewsSearch.java:28)
at main.java.DepartmentCategories_Main.main(DepartmentCategories_Main.java:110)

java.net.UnknownHostException: www.sears.com
at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
at java.net.Socket.connect(Socket.java:589)
at sun.net.NetworkClient.doConnect(NetworkClient.java:175)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:211)
at sun.net.www.http.HttpClient.New(HttpClient.java:308)
at sun.net.www.http.HttpClient.New(HttpClient.java:326)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:1167)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1103)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:997)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:931)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1511)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1439)
at extractData.productHierarchySearch.getHierarchy(productHierarchySearch.java:27)
at main.java.DepartmentCategories_Main.main(DepartmentCategories_Main.java:115)

任何想法，可能是什么原因？让我知道是否需要更多信息

编辑:我尝试了 ping 命令，我意识到这是互联网连接。我在 ssh 服务器上运行该程序，想知道如何防止代码停止。我希望它等待连接。

Answer 1

其他答案解决了您看到的特定异常。但是，您(可能)真的在问该怎么办。

正如您所遇到的，在现实世界中，事情有时会失败(并抛出异常)。在预计异常是暂时的情况下，您应该捕获异常并安排重试该操作。您可能想立即重试，但更多时候最好稍等片刻再重试。这个想法是让发生的任何问题在重试之前得到修复(或自行修复)。

记录异常(或至少是摘要)通常是个好主意，以防可能需要运算符(operator)干预才能让事情重新开始。

如果在该操作成功之前无法继续，您可能希望在循环中重试。如果您可以处理其他事情，则可以通过将问题项目放在工作队列的后面来实现重试。

对于前一种情况:

doWork("www.sears.com");

成为

while (true) {
    try {
        doWork("www.sears.com");
        break;
    } catch (UnknownHostException e) {
        logger.log(e.getMessage());
        Thread.sleep(10000);
    }
}