Java UnknownHostException 何时以及为何？
我正在尝试从处理草图发布到网站。 （处理基本上是在一个奇特的环境中运行的Java）。我正在使用这个库： http://libraries.seltar.org/postToWeb/ 但我不不知道这是否有什么不同。从下面的堆栈跟踪可以看出，这只是 Java 标准库的包装器。
无论如何，重要的一点是主机“mysite.com”已启动并正在运行。我是从浏览器看到的。但是当我尝试从 Java 发布到它时，我只是出现 UnknownHostException。
鉴于该网站已启动。这还可能意味着什么？
该程序当前正在处理环境中运行。大概是作为一个小程序。
java.net.UnknownHostException: mysite.com
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:195)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at sun.net.NetworkClient.doConnect(NetworkClient.java:163)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:233)
at sun.net.www.http.HttpClient.New(HttpClient.java:306)
at sun.net.www.http.HttpClient.New(HttpClient.java:323)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:970)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:911)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:836)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1014)
at org.seltar.Bytes2Web.PostToWeb._post(PostToWeb.java:90)
at org.seltar.Bytes2Web.ByteToWeb.post(ByteToWeb.java:66)
at experimentPostToWeb.keyPressed(experimentPostToWeb.java:35)
at processing.core.PApplet.handleKeyEvent(Unknown Source)
at processing.core.PApplet.dequeueKeyEvents(Unknown Source)
at processing.core.PApplet.handleDraw(Unknown Source)
at processing.core.PApplet.run(Unknown Source)
at java.lang.Thread.run(Thread.java:662)
I'm trying to post to a website from a Processing Sketch. (Processing is basically Java running in a fancy environment). I'm using this library : http://libraries.seltar.org/postToWeb/ but I don't know if that makes a difference. You can see from the stack trace below that this is just a wrapper for the Java standard library.
Anyway, the important point is that the host "mysite.com" is up and running. I am seeing it from the browser. But when I try to post to it from Java I just get the UnknownHostException appearing.
Given that the site is up. What else might this mean?
The program is currently running inside the Processing environment. Presumably as an Applet.
java.net.UnknownHostException: mysite.com
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:195)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at java.net.Socket.connect(Socket.java:478)
at sun.net.NetworkClient.doConnect(NetworkClient.java:163)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:233)
at sun.net.www.http.HttpClient.New(HttpClient.java:306)
at sun.net.www.http.HttpClient.New(HttpClient.java:323)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:970)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:911)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:836)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1014)
at org.seltar.Bytes2Web.PostToWeb._post(PostToWeb.java:90)
at org.seltar.Bytes2Web.ByteToWeb.post(ByteToWeb.java:66)
at experimentPostToWeb.keyPressed(experimentPostToWeb.java:35)
at processing.core.PApplet.handleKeyEvent(Unknown Source)
at processing.core.PApplet.dequeueKeyEvents(Unknown Source)
at processing.core.PApplet.handleDraw(Unknown Source)
at processing.core.PApplet.run(Unknown Source)
at java.lang.Thread.run(Thread.java:662)
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代理问题。您的 DNS 查找失败是因为在 LAN 内没有向该网站注册任何内容，并且 ProxySelector 未使用代理来访问互联网。
Proxy problems. Your DNS lookup failure occurs because within the LAN there is nothing registered to that website and the ProxySelector is not using a proxy to reach out to the internet.
您可能只使用 link() 处理方法
http://processing.org/reference/link_.html
这样您就可以验证处理实际上正在查看您的页面，然后您可以尝试发布到该页面。
You could probably just use the link() method of processing
http://processing.org/reference/link_.html
That way you can verify that processing is actually seeing your page, and from there on you can try to post to it.
您可以将 -Djava.rmi.server.hostname= -Dremoting.bind_by_host=false 添加到服务器上的运行脚本中
You can add -Djava.rmi.server.hostname= -Dremoting.bind_by_host=false to the run script at the server