未知主機異常

Question

try { 
{
    long startTime = System.currentTimeMillis();

        String source="s";
        String source1="s";
        URL google = new URL("http://google.com/"); 
        HttpURLConnection yc =(HttpURLConnection)google.openConnection(); 
        BufferedReader in = new BufferedReader(new InputStreamReader(yc.getInputStream())); 
        String inputLine;


        while ((inputLine = in.readLine()) != null) { 
            source=source.concat(inputLine);
        }
        in.close();

        yc.disconnect();

    }

long endTime1 = System.currentTimeMillis();
System.out.println("Total elapsed time in execution of method callMethod() is :"+ (endTime1-startTime));


    } 
}

當我通過命令提示符嘗試上述操作時，我得到了

java.net.UnknownHostException: google.com 
at java.net.PlainSocketImpl.connect(Unknown Source) 
at java.net.Socket.connect(Unknown Source) 
at java.net.Socket.connect(Unknown Source) 
at sun.net.NetworkClient.doConnect(Unknown Source) 
at sun.net.www.http.HttpClient.openServer(Unknown Source) 
at sun.net.www.http.HttpClient.openServer(Unknown Source) 
at sun.net.www.http.HttpClient.<init>(Unknown Source) 
at sun.net.www.http.HttpClient.New(Unknown Source) 
at sun.net.www.http.HttpClient.New(Unknown Source) 
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source) 
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source) 
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source) 
at ScagntJavaHttp.httpMakeRequest(ScagntJavaHttp.java:185) 
at test.main(test.java:23)

任何人都可以幫助我解決這個問題嗎？

Answer 1

當您收到java.net.UnknownHostException並檢查您的互聯網連接和主機是否存在時，嘗試從您的主機 url 中刪除http://

Answer 2

我相信這是一個代理問題。 嘗試查看您的瀏覽器中是否有代理定義，然后進行設置：

    ProxySelector.setDefault(new ProxySelector() {

        @Override
        public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
            throw new RuntimeException("Proxy connect failed", ioe);
        }

        @Override
        public List select(URI uri) {
            return Arrays
                .asList(new Proxy(Proxy.Type.HTTP,
                                  new InetSocketAddress(proxyHost,
                                                        proxyPort)));
        }
    });

要查看IE中是否有代理定義，go到工具-Internet選項-連接-局域網設置