用URL类访问网络抛出java.net.UnknownHostException?

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java.net.UnknownHostException
这个已经很明确了吧，为止主机或者你的url写错了
把你的url发出来
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如果你是通过代理上网的，也要在程序里设代理
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InputStream input;
HttpURLConnection con = (HttpURLConnection) (sourceURL).
openConnection();
con.setRequestProperty("Proxy-Authorization",
"Basic " + new BASE64Encoder().encode("username:password".getBytes()));
URL url = new URL("http://www.somewhere.net/software/ACDSee60.zip");

System.out.println
(con.getResponseCode() + " : " + con.getResponseMessage());

input = con.getInputStream();