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Connecting RESTful client to local virtual machine

I am trying to connect my desktop Windows 10 machine with local Virtual Machine having Ubuntu 16.04.
I have written a RESTful client in following way to connect to this machine in following way.
public class NetClientGet {
// http://localhost:8080/RESTfulExample/json/product/get
public static void main(String[] args) {
try {
//URL url = new URL("http://localhost:8080/RESTfulExample/json/product/get");
URL url = new URL("http://192.168.56.101:8998/sessions");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept", "application/json");
if (conn.getResponseCode() != 200) {
throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
}
BufferedReader br = new BufferedReader(new InputStreamReader(
(conn.getInputStream())));
String output;
System.out.println("Output from Server .... \n");
while ((output = br.readLine()) != null) {
System.out.println(output);
}
conn.disconnect();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
I am able to ssh into this virtual machine via Putty.The peculiarity is that till I don't ssh via Putty in this virtual machine, this code produces error as follows:
java.net.ConnectException: Connection timed out: connect
at java.net.DualStackPlainSocketImpl.connect0(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 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.plainConnect0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at java.net.HttpURLConnection.getResponseCode(Unknown Source)
at com.mkyong.rest.client.NetClientGet.main(NetClientGet.java:22)
So what is actually missing in my approach of making connection?

Java HttpsURLConnection instance not giving response code

I am trying to get a token for an API with this code and it throws exception when it tries to get and check the response code. It is my understanding that url.openConnection() does not actually connect? I tried url.connect() but that didn't work for me. When I
System.out.println(conn);
i just get this:
sun.net.www.protocol.https.DelegateHttpsURLConnection:https://fim.api.ENV.fleetmatics.com/token
and when I
System.out.println(conn.getResponseCode());
I do not get anything.
public TokenGenerator(String username, String password, String getTokenUri){
_username = username;
_password = password;
_getTokenUri = getTokenUri;
_authString = GetToken();
}
private String GetToken(){
String authString = "";
try
{
// Get authentication, Base64 encoded, string
String basicAuth = BuildBasicAuth(_username, _password);
URL url = new URL(_getTokenUri);
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty("Authorization", basicAuth);
conn.setRequestProperty("Accept", "text/plain");
conn.setDoOutput(false);
// Execute request;, read response. If we do not receive a 200 OK, throw exception
if (conn.getResponseCode() != HttpsURLConnection.HTTP_OK) {
throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
}
When I try to connect with this code, I get the stack trace below..
HttpsURLConnection conn = (HttpsURLConnection)url.openConnection();
conn.connect();
conn.setRequestMethod("GET");
conn.setRequestProperty("Authorization", basicAuth);
conn.setRequestProperty("Accept", "text/plain");
conn.setDoOutput(false);
java.net.UnknownHostException: fim.api.ENV.fleetmatics.com
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.security.ssl.SSLSocketImpl.connect(Unknown Source)
at sun.security.ssl.BaseSSLSocketImpl.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.protocol.https.HttpsClient.<init>(Unknown Source)
at sun.net.www.protocol.https.HttpsClient.New(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(Unknown Source)
at TokenGenerator.GetToken(TokenGenerator.java:52)
at TokenGenerator.<init>(TokenGenerator.java:39)
at Program.main(Program.java:10)
Exception in thread "main" java.lang.NullPointerException
at java.util.Date.getMillisOf(Unknown Source)
at java.util.Date.after(Unknown Source)
at TokenGenerator.GetAuthString(TokenGenerator.java:28)
at Program.main(Program.java:13)

Java SocketException Error

I'm trying to understand how an API works to develop using it.
I need to connect in that API and authenticate.
The authentication method is POST.
Here is my code:
try {
URL url = new URL("http://api.olhovivo.sptrans.com.br/v0/Login/Autenticar");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("POST");
connection.addRequestProperty("token", "77b495072cf8b35a0b187218721871e4790dd6b92asxald6a29");
int code = connection.getResponseCode();
System.out.println("Response Code: " + code);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
Here is the error I get:
java.net.SocketException: Permission denied: connect
at java.net.DualStackPlainSocketImpl.connect0(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 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.plainConnect0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at java.net.HttpURLConnection.getResponseCode(Unknown Source)
at TestandoAPIOlhoVivo.main(TestandoAPIOlhoVivo.java:19)
What am I doing wrong?

Getting connection timeout while connecting to URL to get the IP details

Following is my code which is trying to connect to different URL's which provides details about the IP address.
public static void main(String args []) throws Exception, URISyntaxException {
String ip = "2.51.255.200";
// http://whois.net/ip-address-lookup/
// http://www.geobytes.com/IpLocator.htm?GetLocation&IpAddress=162.115.44.104
// http://whatismyipaddress.com/ip/162.115.44.104
// http://freegeoip.net/csv/137.188.83.252
URL url = new URL("http://whatismyipaddress.com/ip/162.115.44.104");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.3 Safari/537.31");
connection.connect();
InputStream is = connection.getInputStream();
int status = connection.getResponseCode();
if (status != 200) {
return;
}
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
for (String line; (line = reader.readLine()) != null;) {
//this API call will return something like:
// "2.51.255.200","AE","United Arab Emirates","03","Dubai","Dubai","","x-coord","y-coord","",""
// you can extract whatever you want from it
System.out.println(line);
}
}
When I am running this code it is giving me connection timeout exception as below.
Exception in thread "main" java.net.ConnectException: Connection timed out: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.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 com.vzw.velite.services.TestURL.main(TestURL.java:22)
I am not sure what is missing here, I am connected to internet and I am running this code in my Eclipse Juno IDE.

URLConnection class java.net.ConnectException: Connection refused: connect

I am programming on a system with client running Java Applet on one end and server on the other. Now I have the client and server on the same computer. But as a client, I cannot see the applet and I get error like below:
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(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 sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
at MainJApplet.init(MainJApplet.java:58)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.net.NetworkClient.doConnect(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.openServer(Unknown Source)
at sun.net.www.http.HttpClient.<init>(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.http.HttpClient.New(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.connect(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
at RequestServer.sendRequest(RequestServer.java:25)
at createGUI.createEditingBar(createGUI.java:1313)
at GUI.createAndShowGUI(GUI.java:813)
at MainJApplet.init(MainJApplet.java:137)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
java.net.ConnectException: Connection refused: connect
java.lang.NullPointerException
at createGUI.createEditingBar(createGUI.java:1315)
at GUI.createAndShowGUI(GUI.java:813)
at MainJApplet.init(MainJApplet.java:137)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Exception: java.lang.NullPointerException
Below is where the problem traced back:
URL url = new URL(ipAddr);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream()); // exception happens
I checked http://localhost:8080/ and port conflict. I have turn off windows firewall and yet the problem exists. Can someone kindly point me some direction? Any advice would be great! Thanks ahead!
I apologize for the long code. The first is for client.
import javax.swing.*;
import java.awt.*;
import java.net.*;
import java.io.*;
public class MainJApplet extends JApplet {
GUI gui = new GUI();
Thread renewThread;
public void init() {
//pass parameters from url to applet
String filePath = this.getParameter("FilePath");
//temporary solution to bypass the new extention
String userName = this.getParameter("UserName");
String ipAddr = this.getParameter("IpAddress");
String userLevel = this.getParameter("UserLevel");
String ticket = this.getParameter("Ticket");
String accessMode = this.getParameter("AccessMode"); //1-normal 2-shared 3-email
//sharedTo will be get from the file path infor
String sharedTo = this.getParameter("ShareTo");
String type = this.getParameter("Type");
gui.shareTo = sharedTo;
gui.ticket = ticket; //this gui.ticket is used to varify email access, will be replaced
String relativePath = "";
try {
//connect to servlet
URL url = new URL(ipAddr);
URLConnection connection = url.openConnection();
connection.setDoOutput(true);
OutputStreamWriter out = new OutputStreamWriter(connection.getOutputStream());
//Passing NAME+FILE+TICKET+TYPE to server at the initialization stage
out.write("IN");
out.write(userName + "#");
out.write(filePath + "#");
out.write(ticket + "#");
out.write(type + "#");
out.close();
//Wait for server response
BufferedReader in = new BufferedReader(
new InputStreamReader(
connection.getInputStream()));
String dcodedStr;
StringBuffer decodedStringBuffer = new StringBuffer("");
while ((dcodedStr = in.readLine()) != null) {
decodedStringBuffer.append(dcodedStr);
}
String dStr = decodedStringBuffer.toString();
in.close();
if (dStr.equals("NOT_AUTHORIZED")) { //not passing authentication check
JOptionPane.showMessageDialog(new JFrame(),
"Access Denied",
"Warning!",
JOptionPane.ERROR_MESSAGE);
return;
} else {//pass authentication check
String[] initResp = dStr.split("#");
gui.FID = initResp[0]; //file ID
gui.EditMode = Boolean.parseBoolean(initResp[1]);
gui.userLevel = 1; //temporary set all as normal user
boolean firstOpen = Boolean.parseBoolean(initResp[2]);
relativePath = initResp[3];
if (initResp[4].trim().equals("normal")) {//owner
gui.accessMode = 1;
} else {//shared user
gui.accessMode = 2;
}
}
}catch(UnknownServiceException exp){
exp.printStackTrace();
}catch(IOException ex){
ex.printStackTrace();
}catch (Exception e) {
e.printStackTrace();
}
}
public void destroy() {
gui.check_upon_window_close();
if (gui.is_new_drawing == 0) {
//2010.9.29 workDir -> FID
if (gui.EditMode) {
RequestServer.canClose(gui.IpAddress, gui.user, gui.FID);
} else {
RequestServer.canCloseNoEdit(gui.IpAddress, gui.user, gui.FID);
}
}
renewThread.stop();
}
}

Based off your comments my guess is that your server is binding to the loopback address (127.0.0.1, aka localhost). You didn't post what the server software is, but change it's configuration so that it binds on 0.0.0.0 instead. That should fix your issue.