运行这段代码出现连接超时：
Document doc = Jsoup.connect(url).get();
String title = doc.title();
System.out.println("URL Doc Title:"+title);
后台错误信息Error Trace:
java.net.SocketTimeoutException: connect timed out
at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.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 org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:449)
at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:434)
at org.jsoup.helper.HttpConnection.execute(HttpConnection.java:181)
at org.jsoup.helper.HttpConnection.get(HttpConnection.java:170)
原因是因为运行环境使用了proxy。只要设置java的网路代理就可以：
System.setProperty("http.proxyHost", "10.2.1.100"); //replace with your proxy host
System.setProperty("http.proxyPort", "80"); //replace with your proxy port
Document doc = Jsoup.connect(url).get();
String title = doc.title();
System.out.println("URL Doc Title:"+title);