URL realUrl = new URL("xxx.xxxx.com");
URLConnection conn = realUrl.openConnection();
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");
conn.setDoOutput(true);
conn.setDoInput(true);
out = new PrintWriter(new OutputStreamWriter(conn.getOutputStream()));
out.print(param);
out.flush();
in = new BufferedReader(
new InputStreamReader(conn.getInputStream()));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buf = new byte[1024];
int len = 0;
InputStream is = conn.getInputStream();
while ((len = is.read(buf)) != -1) {
System.out.println(len);
baos.write(buf, 0, len);
}
Linux OS，Tomcat服务器，"xxx.xxxx.com"是一个不正确的URL .
I am expecting a UnknownHostException all the time, but sometimes what I am getting is UnknownHostException.
UnknownHostException错误消息
java.net.Socks.Socket.connect中java.net.SocksSocketImpl.connect（SocksSocketImpl.java:392）上的java.net.AbstractPlainSocketImpl.connect（AbstractPlainSocketImpl.java:178）中的java.net.UnknownHostException：xxx.xxxx.com （Socket.java:579）sun.net.NetworkClient.doConnect（NetworkClient.java:178）at sun.net.www.http.HttpClient.openServer（HttpClient.java:432）
SocketTimeoutException错误消息
java.net.SocketTimeoutException：java.net.AbstractPlainSocketImpl.connectToAddress（AbstractPlainSocketImpl.java：）java.net.AbstractPlainSocketImpl.doConnect（AbstractPlainSocketImpl.java:339）上java.net.PlainSocketImpl.socketConnect（Native Method）的连接超时时间 . 200）at java.net.SocksSocketImpl.connect（AbstractPlainSocketImpl.java:182）at java.net.SocksSocketImpl.connect（SocksSocketImpl.java:392）at java.net.Socket.connect（Socket.java:579）at sun . net.netNetworkClient.doConnect（NetworkClient.java:178）at sun.net.www.http.HttpClient.openServer（HttpClient.java:432）
1 回答
只是猜测 - 有时您的应用程序无法连接到DNS服务器吗？这可以解释为什么你收到一个SocketTimeoutException而不是UnknownHostException - 你的应用程序试图查找主机名但它超时才能确定主机不存在 .