Java tutorial sample code throws: java.net.SocketException: Connection reset - what does cause it?

Question

So this is a beginner's question.

When executing the sample code from the working with urls chapter it throws:

Exception in thread "main" java.net.SocketException: Connection reset at java.net.SocketInputStream.read(SocketInputStream.java:189) ...

Origin is the openStream() method.

Here is the code:

    import java.net.*;
    import java.io.*;

    public class URLReader {

       public static void main(String[] args) throws Exception {

          URL oracle = new URL("http://www.oracle.com/");
          BufferedReader in = new BufferedReader(
          new InputStreamReader(oracle.openStream()));

          String inputLine;
          while ((inputLine = in.readLine()) != null) {
             System.out.println(inputLine);
          }
          in.close();
       }
    }

I know there are similar threads regarding that topic, but i could not find an answer that suits me.

What I've tried so far:

I have set the proxy host as suggested here. Command was: java -Dhttp.proxyHost=dslb-088-071-100-199.pools.arcor-ip.net, I also tried it with inserting System.setProperty("http.proxyHost", "dslb-088-071-100-199.pools.arcor-ip.net"); in the first line of the URLReader class.
I tried JSoup html parser and
org.apache.commons.io.FileUtils.copyURLToFile(URL, File) method to have a similar result.

Whatever I try, I always get the same error: There will happen nothing for 30 seconds or so and then it throws the mentioned SocketException.

I simply dont know how to continue in solving this problem. Helpful would be to get information about what happens in background during the 30seconds before connection reset.

So what could actually cause this Exception?

The smallest hint could help! Thank you!

Can you give us the full code with the proxy host set... Your code by the way executes successfully on my machine. — Μenelaοs
– Μenelaοs, Commented Jun 5, 2013 at 14:29
It should work..... Do you have access to to this url from your browser. — Makky
– Makky, Commented Jun 5, 2013 at 14:30
It gives me an UnknownHostException, as well as on IDEONE. — Djon
– Djon, Commented Jun 5, 2013 at 14:30

6 revs · Accepted Answer · 2021-01-18 12:35:56Z

2

Your code is working fine for JVM's that can connect to the internet.

Based on the original question and discussion: https://chat.stackoverflow.com/rooms/31264/discussion-between-achingfingers-and-meewok it seems that either:

An intermediate firewall is blocking the JVM from making the connection (or another similar network issue).
An operating system firewall, or antivirus that is causing the problems as well.

My suggestion is to try:

Same app on different computer within same network (to see if it is PC specific).
Same app on different network.

edited Jan 18, 2021 at 12:35

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3 Comments

artbristol Over a year ago

} catch (Exception x) { System.out.println("No Connection"); } throws away the exception message and is way worse than just declaring main as throws Exception

Μenelaοs Over a year ago

Yes, except this was just a quick test I picked up somewhere to see if the OP was getting 200 or not. Please see the whole discussion within the chat.

achingfingers Over a year ago

So in my case it has been the antivirus software that was causing the problem. After disabling it's browser protection function everything worked well ... Thank you

Balint Bako · Accepted Answer · 2013-06-05 14:57:00Z

Try Apache HTTPClient. I hope all the imports are included as this code is not tested as it is... Also your 30s is the connection timeout of your client.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.net.ProxySelector;
import java.net.SocketAddress;
import java.net.URI;

import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.conn.params.ConnRoutePNames;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.CoreConnectionPNames;


public class URLReader {

   public static void main(String[] args) throws Exception {
        HttpClient httpclient = new DefaultHttpClient();
        httpclient.getParams().setParameter(
                CoreConnectionPNames.CONNECTION_TIMEOUT, timeOut);
        httpclient.getParams().setParameter(
                CoreConnectionPNames.SO_TIMEOUT, 2 * timeOut);
        httpclient.getParams().setParameter(
                CoreConnectionPNames.STALE_CONNECTION_CHECK, false);
        httpclient.getParams().setParameter(
                CoreConnectionPNames.TCP_NODELAY, true);
        HttpHost proxy = new HttpHost(%proxyhost%, %proxyport%);
        HttpGet httpget = new HttpGet("http://www.oracle.com");
        HttpResponse resp = httpclient.execute(httpget);
        respCode = resp.getStatusLine().getStatusCode();

        BufferedReader br = new BufferedReader(new InputStreamReader(resp
                .getEntity().getContent()));
        String line = null;
        while ((line = br.readLine()) != null) {
            System.out.println(line);
        }
        br.close();
    }
}

Try it why? What problem in the original code does it solve?

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