We Keep Coding

FTPSClient retrievefile() hanging

I'm creating an apache FTPS client (because the remote server won't allow plain FTP). I can connect and delete files without problem, but when using retrieveFile() or retrieveFileStream(), it hangs.
For some reason, very small files do transfer (up to 5792 bytes), but anything else gives the following PrintCommandListener output:
run:
220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
220-You are user number 2 of 50 allowed.
220-Local time is now 19:42. Server port: 21.
220-This is a private system - No anonymous login
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.
AUTH TLS
234 AUTH TLS OK.
USER
331 User OK. Password required
PASS
230 OK. Current restricted directory is /
TYPE A
200 TYPE is now ASCII
EPSV
229 Extended Passive mode OK (|||53360|)
RETR test.txt
150-Accepted data connection
150 7.3 kbytes to download
Here is the code:
try {
FTPSClient ftpClient = new FTPSClient("tls",false);
ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
ftpClient.connect(host, port);
int reply = ftpClient.getReplyCode();
if (FTPReply.isPositiveCompletion(reply)) {
ftpClient.enterLocalPassiveMode();
ftpClient.login(username, password);
ftpClient.enterLocalPassiveMode();
FileOutputStream outputStream = new FileOutputStream(tempfile);
ftpClient.setFileType(FTPClient.ASCII_FILE_TYPE);
ftpClient.retrieveFile("test.txt", outputStream);
outputStream.close();
ftpClient.logout();
ftpClient.disconnect();
}
} catch (IOException ioe) {
System.out.println("FTP client received network error");
}
Any ideas are greatly appreciated.

Typically the FTP command sequence for FTPS connections goes (per RFC 4217) AUTH TLS, PBSZ 0, then USER, PASS, etc. Thus you might try:
FTPSClient ftpClient = new FTPSClient("tls",false);
ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
ftpClient.connect(host, port);
int reply = ftpClient.getReplyCode();
if (FTPReply.isPositiveCompletion(reply)) {
ftpClient.execPBSZ(0);
reply = ftpClient.getReplyCode();
// Check for PBSZ error responses...
ftpClient.execPROT("P");
reply = ftpClient.getReplyCode();
// Check for PROT error responses...
ftpClient.enterLocalPassiveMode();
This explictly tells the server to not buffer the data connection (PBSZ 0), and to use TLS for protecting the data transfer (PROT P).
The fact that you are able to transfer some bytes indicates that the issue is not the usual complication with firewalls/routers/NAT, which is another common FTPS issue.
Hope this helps!

Even if PBSZ 0 and PROT P are called in the correct sequence, sometimes the server does require SSL session reuse which is not the case by default for the client.
For example, the following reply comes when trying to list a directory. As a result no content listing is returned, this way the client seeing as if the directory is empty:
LIST /
150 Here comes the directory listing.
522 SSL connection failed; session reuse required: see require_ssl_reuse option in sftpd.conf man page
To overcome that, custom initialization of the FTPSClient is needed by overriding _prepareDataSocket_() method.
The solution is explained in details here: https://eng.wealthfront.com/2016/06/10/connecting-to-an-ftps-server-with-ssl-session-reuse-in-java-7-and-8/
Working code sample taken from the above link:
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.Socket;
import java.util.Locale;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSessionContext;
import javax.net.ssl.SSLSocket;
import org.apache.commons.net.ftp.FTPSClient;
import com.google.common.base.Throwables;
public class SSLSessionReuseFTPSClient extends FTPSClient {
// adapted from: https://trac.cyberduck.io/changeset/10760
#Override
protected void _prepareDataSocket_(final Socket socket) throws IOException {
if(socket instanceof SSLSocket) {
final SSLSession session = ((SSLSocket) _socket_).getSession();
final SSLSessionContext context = session.getSessionContext();
try {
final Field sessionHostPortCache = context.getClass().getDeclaredField("sessionHostPortCache");
sessionHostPortCache.setAccessible(true);
final Object cache = sessionHostPortCache.get(context);
final Method putMethod = cache.getClass().getDeclaredMethod("put",Object.class, Object.class);
putMethod.setAccessible(true);
final Method getHostMethod = socket.getClass().getDeclaredMethod("getHost");
getHostMethod.setAccessible(true);
Object host = getHostMethod.invoke(socket);
final String key = String.format("%s:%s", host, String.valueOf(socket.getPort())).toLowerCase(Locale.ROOT);
putMethod.invoke(cache, key, session);
} catch(Exception e) {
throw Throwables.propagate(e);
}
}
}
}

Hope someone finds my comment useful after several years.
In my case, I replaced retrieveFile with retrieveFileStream. It requires more code, but at least it works.

For me, I fixed the problem after upgrading Apache Commons Net to 3.8.0.
dependencies {
implementation 'commons-net:commons-net:3.8.0'
...
}

Sending RDF/XML using Sesame or Apache Jena with Sockets

I am trying to send RDF/XML from a Client to a Server using sockets in Java. When I send the information the Server program hangs and does not receive the info unless I close the Socket or OutputStream on the Client side. Even if I flush the OutputStream on the Client-side the Server does not receive the data unless I close the Socket/Stream. I would like to send the information without closing the socket. Here is some example code for the Client (using Sesame):
import java.io.*;
import java.net.*;
import org.openrdf.rio.*;
import org.openrdf.rio.helpers.*;
import org.openrdf.model.URI;
import org.openrdf.model.Model;
import org.openrdf.model.ValueFactory;
import org.openrdf.model.Statement;
import org.openrdf.model.impl.*;
import org.openrdf.model.vocabulary.*;
public class SimpleRDFClient {
private Socket socket = null;
public static void main(String[] args) {
new SimpleRDFClient(args[0],Integer.parseInt(args[1])).launch();
}
public SimpleRDFClient(String host, int port) {
try {
socket = new Socket(host,port);
} catch (IOException ex) {
ex.printStackTrace();
}
}
public void launch() {
try {
OutputStream out = socket.getOutputStream();
BufferedOutputStream dos = new BufferedOutputStream(out);
Model model = new LinkedHashModel();
ValueFactory factory = new ValueFactoryImpl();
URI clive = factory.createURI("http://www.site.org/cliveAnderson");
Statement st = factory.createStatement(clive, RDF.TYPE, FOAF.PERSON);
model.add(st);
Rio.write(model,dos,RDFFormat.RDFXML);
dos.flush();
//Some other stuff
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
And the Server Handler:
import java.io.*;
import java.net.*;
import org.openrdf.rio.*;
import org.openrdf.rio.helpers.*;
import org.openrdf.model.*;
import org.openrdf.model.impl.*;
public class SimpleRDFSHandler implements Handler {
public void handleConnection(Socket socket) {
Model model = null;
try {
InputStream in = socket.getInputStream();
model = Rio.parse(in,"www.blah.com",RDFFormat.RDFXML);
for (Statement st: model) {
System.out.println(st);
}
} catch (Exception ex) {
ex.printStackTrace();
}
}
}
The problem seems to come from the Rio.parse() method hanging (I think because it does not know when the input ends). I get a similar problem when I use the Jena api in a similar way, i.e. using Model.write(outputstream,format) and Model.read(inputstream,format) instead of Rio. I have looked at the source and the javadoc for ages but can't solve the problem. I think it must be something simple I have misunderstood. Any ideas?

I don't think this is in any way a Jena/Sesame specific issue but rather a Java issue around your use of sockets. Is there actually a practical reason you want to not close the socket?
I don't see why this would ever be advisable unless you want to continuously post data and process it as it is received on the server side? If this is the case both Jena and Sesame have APIs that specifically allow you to control what happens to data as it parsed in so that you aren't reliant on your read calls from completing before you process the data.
Also why use sockets, both Sesame and Jena have comprehensive HTTP integration which is much easier to use and deploy than rolling your own socket based server and clients.
The Ugly Hacky Solution
If you really must do this then there is a workaround but it is somewhat horrid and fragile and I would strongly recommend that you do not do this.
On the client side after you write the data write a sequence of bytes that indicate end of stream. On the server side wrap the socket stream with a custom InputStream implementation that recognizes this sequence and stops returning data when it is seen. This should allow the Jena/Sesame code which is expecting the stream to finish to function correctly.
The sequence of bytes need to be carefully chosen such that it won't naturally occur in the data.
To be honest this is a terrible idea, if your aim is to continuously post data this won't really solve your problem because then you'll just be leaking sockets server side unless you put the server side socket handling code in a while (true) loop which is likely another bad idea.

Multicast Client System for iOS with a Java Server-Side

CONTEXT:
I am creating a cross-platform multicast client-server system for mobile. I have created the server side in Java. I also created the android client side and it works perfectly.
WHAT I WANT TO KNOW:
I want to know if I could create a client side in iOS using the listener program in this example http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/antony/example.html that would be compatible with my server-side that I created in Java.
If the above example will not work is there a way I can still use my Java server-side and create a native iOS client system that is compatible with the Java server-side?
SAMPLE CODE OF JAVA SERVER SIDE FOR REFERENCE:
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
//more imports...
class Server2 {
public static MulticastSocket ms1;
public static void main(String[] args) throws IOException {
try {
InetAddress sessAddr1 = InetAddress.getByName("224.2.76.24");
ms1 = new MulticastSocket(5500);
ms1.joinGroup(sessAddr1);
while(true) {
byte[] message = new byte[1024];
message = getIpAddress().getBytes();
DatagramPacket dp = new DatagramPacket(message, message.length, sessAddr1, 5500);
ms1.send(dp);
System.out.println(String.format("Sent message: %s", message));
Thread.sleep(1000);
}
} catch (Exception e) {
System.out.println(String.format("Error: %s", e));
}
}
public static String getIpAddress() {
InetAddress ip;
try {
ip = InetAddress.getLocalHost();
return(String.format("%s",ip.getHostAddress()));
} catch (Exception e) {
return("false");
}
}
}
I tested the listener code in the link and it worked perfectly.

Should not be a problem. iOS is POSIX compliant and Objective-C is defined on top of ANSI C, so you could paste the code you linked to with minor modifications straight into your project, build a simple wrapper to Objective-C and your app should compile, run and work as desired.

NoClassDefFound when running from cmd but not Eclipse

I know I'll feel like a tard when I figure this one out. I'm trying to do a very simple client/server and run it from the command line. It runs fine from Eclipse, but not from cmd. Here's the client:
package com.mycompany.pdr.client;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.UnknownHostException;
public class SimpleClientSend {
public static void main(String[] args) {
String host = "127.0.0.1";
int port = 11048;
String dataToSend = "HELLO SERVER";
System.out.println("> Trying to connect...");
System.out.println("> Opening connection to server [" + host + ":"
+ port + "]...");
Socket socket1Connection;
try {
socket1Connection = new Socket(host, port);
System.out.println("> Connected...");
System.out.println("> Trying to write data... [ " + dataToSend + " ]");
BufferedOutputStream bos = new BufferedOutputStream(
socket1Connection.getOutputStream());
/*
* Instantiate an OutputStreamWriter object with the optional
* character encoding. e.g. UTF-8
*/
OutputStreamWriter osw = new OutputStreamWriter(bos, "US-ASCII");
// Writing to server
osw.write(dataToSend);
osw.flush();
System.out.println("> Writing to server done...");
socket1Connection.close();
} catch (UnknownHostException e) {
System.out.println(e.getLocalizedMessage());
System.out.println("Unknown Host. Please check if the server is running at the IP & port");
//e.printStackTrace();
} catch (IOException e) {
System.out.println(e.getLocalizedMessage());
System.out.println("Could not send data. Giving up.");
//e.printStackTrace();
}
System.out.println("> End of connection...");
}
}
My directory structure is : (MyWorkspace)/myProject/com/mycompany/pdr/client
I run javac SimpleClientSend.java from inside the client folder, and I get a class file, no errors. I run java SimpleClientSend and I get a NoClassDefFound message:
Exception in thread "main" java.lang.NoClassDefFoundError: SimpleClientSend (wrong name: com/iai/pdr/client/SimpleClientSend)
I've tried using -cp . when I run java to follow the suggestions of every other article out there(but what's the point if . is already in my classpath?), I've tried running it from outside the client folder, everything just gives me the same error. In eclipse, all I had to do was paste the java files into a blank project and it ran. What am I doing wrong here?

You need to specify the full name of your class (including package).
java com.mycompany.pdr.client.SimpleClientSend
It is important that the base of the structure for your class(es) is included in your class path. Normally . is included, so if you run the command above when your are in myProject it should work.
If you are in another folder you should add the myProject to your class path, such as:
java -cp ...MyWorkspace/myProject com.mycompany.pdr.client.SimpleClientSend
The ... of course is since I don't know your full path.

Issue using Twitter REST API

I have a list of screen names on Twitter and I wish to get meta data about their twitter profile. I am using Twitter's REST API for the same. The users/show method is apt for my task. The API documentation clearly states that it requires no authentication. Here's the code I wrote for my task:
package Twitter;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
public class TwitterAPI {
private static String url = "http://api.twitter.com/1/users/show/";
/*
* Sends a HTTP GET request to a URL
* #return - The response from the end point
*/
public static String sendGetRequest(String endpoint, String screen_name) {
String result = null;
if (endpoint.startsWith("http://")){
//Send HTTP request to the servlet
try {
//Construct data
StringBuffer data = new StringBuffer();
//Send data
String urlStr = endpoint ;
if(screen_name!=null && screen_name.length() > 0){
urlStr += screen_name + ".json";
}
System.out.println(screen_name.length());
System.out.println("The URL call is: " + urlStr);
URL url = new URL(urlStr);
URLConnection conn = url.openConnection ();
//Get the response
BufferedReader rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuffer sb = new StringBuffer();
String line;
while((line = rd.readLine())!=null){
sb.append(line);
}
rd.close();
result = sb.toString();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
//If API issue, collect screen names to write to API issue file
System.out.println("Twitter API issue :" + screen_name);
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return result;
}
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
String result = sendGetRequest(url, "denzil_correa");
System.out.println(result);
}
}
However, on running the same I receive the following exception :
13
The URL call is: http://api.twitter.com/1/users/show/denzil_correa.json
Twitter API issue :denzil_correa
java.net.ConnectException: Connection timed out: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:365)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:227)
null
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:214)
at java.net.Socket.connect(Socket.java:531)
at java.net.Socket.connect(Socket.java:481)
at sun.net.NetworkClient.doConnect(NetworkClient.java:157)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
at sun.net.www.http.HttpClient.<init>(HttpClient.java:233)
at sun.net.www.http.HttpClient.New(HttpClient.java:306)
at sun.net.www.http.HttpClient.New(HttpClient.java:323)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:783)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:724)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:649)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:972)
at Twitter.TwitterAPI.sendGetRequest(TwitterAPI.java:43)
at Twitter.TwitterAPI.main(TwitterAPI.java:76)
The URL is correct as when I try the URL : http://api.twitter.com/1/users/show/denzil_correa.json in my browser I receive the following:
{"time_zone":"Mumbai","description":"","lang":"en","profile_link_color":"1F98C7","status":{"coordinates":null,"contributors":null,"in_reply_to_screen_name":"shailaja","truncated":false,"in_reply_to_user_id":14089830,"in_reply_to_status_id":16789217674,"source":"web","created_at":"Tue Jun 22 19:43:46 +0000 2010","place":null,"geo":null,"favorited":false,"id":16793898396,"text":"#shailaja Harsh !"},"profile_background_image_url":"http://s.twimg.com/a/1276711174/images/themes/theme2/bg.gif","profile_sidebar_fill_color":"DAECF4","following":false,"profile_background_tile":false,"created_at":"Sun Jun 29 20:23:29 +0000 2008","statuses_count":1157,"profile_sidebar_border_color":"C6E2EE","profile_use_background_image":true,"followers_count":169,"contributors_enabled":false,"notifications":false,"friends_count":246,"protected":false,"url":"http://https://sites.google.com/a/iiitd.ac.in/denzilc/","profile_image_url":"http://a3.twimg.com/profile_images/643636081/Cofee_Mug_normal.jpg","geo_enabled":true,"profile_background_color":"C6E2EE","name":"Denzil Correa","favourites_count":3,"location":"India","screen_name":"denzil_correa","id":15273105,"verified":false,"utc_offset":19800,"profile_text_color":"663B12"}
which is in the JSON format I want.
Kindly let me know if I am doing anything stupid here.
Regards,
--Denzil
Hank/Splix as told I tried using the HTTP Components Client. Here's my modified code :
package Twitter;
import java.io.IOException;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
public class TwitterAPI {
private static String url = "http://api.twitter.com/1/users/show/denzil_correa.json";
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet(url);
try {
HttpResponse response = httpclient.execute(httpget);
System.out.println(response.toString());
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Here's the error I receive:
org.apache.http.conn.HttpHostConnectException: Connection to http://api.twitter.com refused
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:127)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:147)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:108)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:415)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:641)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:576)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:554)
at Twitter.TwitterAPI.main(TwitterAPI.java:30)
Caused by: java.net.ConnectException: Connection timed out: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:365)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:227)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:214)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:378)
at java.net.Socket.connect(Socket.java:531)
at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:123)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:123)
... 7 more
Surprisingly this also gives a similar exception to the code written for handling HTTP responses manually. I understand that manually handling HTTP responses may be sub-optimal but currently I am not looking at writing optimal code. I would like to get my task done even if it means to be quick & dirty.
Just to let you know, I can successfully call the Facebook Graph API using the first code I posted. I am receiving the same response I would receive if I paste the URL in my browser.
I will also try using the Twitter4J API once again and check if I can get my task done. Will keep you updated.
So, here's the code using Twitter4J :
package Twitter;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.User;
public class TwitterAPI {
/**
* #param args
*/
public static void main(String[] args) {
Twitter unauthenticatedTwitter = new TwitterFactory().getInstance();
try {
User user = unauthenticatedTwitter.showUser("denzil_correa");
System.out.println(user.getLocation());
} catch (TwitterException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Pretty straightforward as expected using the API. However, here's the error I receive:
Jun 23, 2010 7:12:10 PM twitter4j.internal.logging.CommonsLoggingLogger info
INFO: Using class twitter4j.internal.logging.CommonsLoggingLoggerFactory as logging factory.
Jun 23, 2010 7:12:11 PM twitter4j.internal.logging.CommonsLoggingLogger info
INFO: Use twitter4j.internal.http.HttpClientImpl as HttpClient implementation.
TwitterException{statusCode=-1, retryAfter=0, rateLimitStatus=null}
at twitter4j.internal.http.HttpClientImpl.request(HttpClientImpl.java:316)
at twitter4j.internal.http.HttpClientWrapper.request(HttpClientWrapper.java:68)
at twitter4j.internal.http.HttpClientWrapper.get(HttpClientWrapper.java:90)
at twitter4j.Twitter.showUser(Twitter.java:538)
at Twitter.TwitterAPI.main(TwitterAPI.java:17)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:365)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:227)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:214)
at java.net.Socket.connect(Socket.java:531)
at sun.net.NetworkClient.doConnect(NetworkClient.java:152)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
at com.ibm.net.ssl.www2.protocol.https.c.(c.java:166)
at com.ibm.net.ssl.www2.protocol.https.c.a(c.java:9)
at com.ibm.net.ssl.www2.protocol.https.d.getNewHttpClient(d.java:55)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:724)
at com.ibm.net.ssl.www2.protocol.https.d.connect(d.java:20)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:972)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:385)
at com.ibm.net.ssl.www2.protocol.https.b.getResponseCode(b.java:52)
at twitter4j.internal.http.HttpResponseImpl.(HttpResponseImpl.java:42)
at twitter4j.internal.http.HttpClientImpl.request(HttpClientImpl.java:279)
... 4 more
Again, I see that the error is essentially the same. So, all options tried! I'm sure there's something I am missing here. It would be great if you could point out the same.
Hank, Unfortunately the same doesn't work in Python too :-(
Traceback (most recent call last):
File "", line 1, in
urllib.urlopen("http://api.twitter.com/1/users/show/denzil_correa.json").read()
File "C:\Python26\lib\urllib.py", line 86, in urlopen
return opener.open(url)
File "C:\Python26\lib\urllib.py", line 205, in open
return getattr(self, name)(url)
File "C:\Python26\lib\urllib.py", line 347, in open_http
errcode, errmsg, headers = h.getreply()
File "C:\Python26\lib\httplib.py", line 1060, in getreply
response = self._conn.getresponse()
File "C:\Python26\lib\httplib.py", line 986, in getresponse
response.begin()
File "C:\Python26\lib\httplib.py", line 391, in begin
version, status, reason = self._read_status()
File "C:\Python26\lib\httplib.py", line 349, in _read_status
line = self.fp.readline()
File "C:\Python26\lib\socket.py", line 397, in readline
data = recv(1)
IOError: [Errno socket error] [Errno 10054] An existing connection was forcibly closed by the remote host

As #splix mentioned in the comments, doing this using just java.net is… suboptimal. I've never yet encountered a situation where HttpClient wasn't a better option. Event better is his suggestion of twitter4j; unless you're trying to create an alternative, it's almost always better to use an API wrapper like that vs. handling the raw HTTP interactions yourself.
UPDATE:
#Denzil it's odd that you're getting this same error even with twitter4j (I can't test the code until I get some free time to grab the lib, etc.) so I begin to suspect a problem on Twitter's end. If you have Python installed, try the following:
>>> import urllib
>>> urllib.urlopen("http://api.twitter.com/1/users/show/denzil_correa.json").read()
This worked for me.
UPDATE 2:
This definitely sounds like Twitter is intentionally refusing your requests. Possible reasons could include: your IP is on their blacklist for some reason, proxy voodoo, or things I haven't thought of. To elaborate on the proxy voodoo: I don't know what exactly it's doing to your requests, but it's possible it's adding a header or something that the Twitter API doesn't like. I'd recommend contacting Twitter support (if there is such a thing for API problems) or posting to the mailing list.
BTW, here's a thread from the mailing list that mentions ways to see if you're blacklisted.