Java Server, html client, unable to send messages to server - javascript

i got a little problem with my project. I have a Server written in Java and some clients written in html/js. Connecting works somehow, but as soon as i want to send a message from the client to the server it returns an error: "Uncaught InvalidStateError: Failed to execute 'send' on 'WebSocket': Still in CONNECTING state"
Hopefully some of you awesome guys can look over my code and help me :)
Server Code:
Server.java
public class Server {
static ArrayList<Clients> clientsArrayList = new ArrayList<>();
private static int clientCount = 1;
private static int port;
private static ServerSocket ss;
private Socket socket;
private Clients clienthandler;
static boolean isRunning = true;
public Server(int port) throws IOException {
this.port = port;
setSs(new ServerSocket(port));
}
public void run() throws IOException {
while (isRunning) {
log("Listening on " + port + "...");
socket = getSs().accept();
log("Receiving client... " + socket);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(socket.getOutputStream());
String s;
while ((s = in.readLine()) != null) {
log(s);
if (s.isEmpty()) {
break;
}
}
log("Creating a new handler for this client...");
clienthandler = new Clients(socket, "Client " + clientCount, in, out);
Thread t = new Thread(clienthandler);
clientsArrayList.add(clienthandler);
log("Added to client list");
t.start();
clientCount++;
GUI.texttoclientlog();
}
}
public static ServerSocket getSs() {
return ss;
}
public static void setSs(ServerSocket ss) {
Server.ss = ss;
}
public void log(String logtext) {
System.out.println(logtext);
GUI.texttolog(logtext);
}
}
Clients.java
public class Clients implements Runnable {
private String name;
final BufferedReader in;
final PrintWriter out;
Socket socket;
boolean isloggedin;
public Clients(Socket socket, String name, BufferedReader in, PrintWriter out) {
this.out = out;
this.in = in;
this.name = name;
this.socket = socket;
this.isloggedin = true;
}
#Override
public void run() {
String received;
while (true) {
try {
// receive the string
received = in.readLine();
System.out.println(received);
GUI.messagehandler(this.getName() + ": " + received);
if (received.equals("logout")) {
this.isloggedin = false;
this.socket.close();
break;
}
this.in.close();
this.out.close();
this.out.flush();
this.out.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public String getName() {
return name;
}
}
And the JS client code:
<script>
var connection;
connection = new WebSocket("ws://localhost:6788/");
console.log("connection established");
connection.onmessage = function (e) { console.log(e.data); };
connection.onopen = () => conn.send("Connection established");
connection.onerror = function (error) {
console.log("WebSocket Error" + error);
};
function Send() {
if (connection.readyState === 1) {
connection.send("test");
}
console.log("error sending");
}
</script>

The WebSocket session is established via a handshake.
Post the handshake is complete and the connection is upgraded, the server and client can send messages. Here is a sample WebSocket server in Java.
Update the clients run method to
public void run() {
int len = 0;
byte[] b = new byte[80];
while(true){
try {
len = in.read(b);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if(len!=-1){
byte rLength = 0;
int rMaskIndex = 2;
int rDataStart = 0;
//b[0] is always text in my case so no need to check;
byte data = b[1];
byte op = (byte) 127;
rLength = (byte) (data & op);
if(rLength==(byte)126) rMaskIndex=4;
if(rLength==(byte)127) rMaskIndex=10;
byte[] masks = new byte[4];
int j=0;
int i=0;
for(i=rMaskIndex;i<(rMaskIndex+4);i++){
masks[j] = b[i];
j++;
}
rDataStart = rMaskIndex + 4;
int messLen = len - rDataStart;
byte[] message = new byte[messLen];
for(i=rDataStart, j=0; i<len; i++, j++){
message[j] = (byte) (b[i] ^ masks[j % 4]);
}
System.out.println(new String(message));
b = new byte[80];
}
}
}
based on this SO answer
In my opinion you can leverage the Spring WebSocket support, rather than writing your own. I had created one which also uses ProtoBuf or you can look at the Spring WebSocket getting started guide here

Thats the updated code. it receives the bytes from the html clients. but i have no clue how to decode them :)
Server.java
public class Server {
static ArrayList<Clients> clientsArrayList = new ArrayList<>();
private static int clientCount = 1;
private static int port;
private static ServerSocket ss;
private Socket socket;
private Clients clienthandler;
static boolean isRunning = true;
private InputStream in;
private OutputStream out;
public Server(int port) throws IOException {
Server.port = port;
setSs(new ServerSocket(port));
}
public void run() throws IOException, NoSuchAlgorithmException {
while (isRunning) {
log("Listening on " + port + "...");
socket = getSs().accept();
log("Receiving client... " + socket);
in = socket.getInputStream();
out = socket.getOutputStream();
#SuppressWarnings("resource")
String data = new Scanner(in, "UTF-8").useDelimiter("\\r\\n\\r\\n").next();
Matcher get = Pattern.compile("^GET").matcher(data);
if (get.find()) {
Matcher match = Pattern.compile("Sec-WebSocket-Key: (.*)").matcher(data);
match.find();
byte[] response = ("HTTP/1.1 101 Switching Protocols\r\n" + "Connection: Upgrade\r\n"
+ "Upgrade: websocket\r\n" + "Sec-WebSocket-Accept: "
+ DatatypeConverter.printBase64Binary(MessageDigest.getInstance("SHA-1")
.digest((match.group(1) + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11").getBytes("UTF-8")))
+ "\r\n\r\n").getBytes("UTF-8");
out.write(response, 0, response.length);
log("Creating a new handler for this client...");
clienthandler = new Clients(socket, "Client " + clientCount, in, out);
Thread t = new Thread(clienthandler);
clientsArrayList.add(clienthandler);
log("Added to client list");
t.start();
clientCount++;
GUI.texttoclientlog();
} else {
log("Handshake failed");
}
}
}
public static ServerSocket getSs() {
return ss;
}
public static void setSs(ServerSocket ss) {
Server.ss = ss;
}
public void log(String logtext) {
System.out.println(logtext);
GUI.texttolog(logtext);
}
}
Clients.java
public class Clients implements Runnable {
private String name;
final InputStream in;
final OutputStream out;
Socket socket;
boolean isloggedin;
public Clients(Socket socket, String name, InputStream in, OutputStream out) {
this.out = out;
this.in = in;
this.name = name;
this.socket = socket;
this.isloggedin = true;
}
#Override
public void run() {
int received;
while (true) {
try {
received = in.read();
//how to decode??
System.out.println(received);
GUI.messagehandler(this.getName() + ": " + received);
} catch (IOException e) {
e.printStackTrace();
}
}
}
public String getName() {
return name;
}
}

Related

api layer, exchangerate // IOException : Server returned HTTP response code: 403 for URL

control.java
public class control {
public static void main(String[] args) {
boolean success = true;
String timestamp = "1659072666";
String base = "USD";
String date = "2022-07-29";
double GBP = 0.82011;
double JPY = 133.000499;
double EUR = 0.979105;
excJSON vwJson = new excJSON();
exc vw = vwJson.getexc(success, timestamp, base, date, GBP, JPY, EUR);
excDAO vwDao = new excDAO();
vwDao.intertexc(1, vw);
}
}
exc.java
public class exc {
String base;
String date;
String timestamp;
public String getbase() {
return base;
}
public void setbase(String base) {
this.base = base;
}
public String getdate() {
return date;
}
public void setdate(String date) {
this.date = date;
}
public String gettimestamp() {
return timestamp;
}
public void settimestamp(String timestamp) {
this.timestamp = timestamp;
}
}
excDAO.java
import java.sql.Statement;
import java.sql.Connection;
//import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
//import java.util.Enumeration;
public class excDAO {
static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/test?useSSL=false";
static final String USERNAME = "root"; // DB ID
static final String PASSWORD = "************"; // DB Password
private Connection conn = null;
private Statement stmt = null;
private ResultSet rs = null;
public void intertVillageWeather(int id, exc v) {
String query = "INSERT INTO exchangerate"
+ " VALUE(" + id +",'"+v.gettimestamp() + "','" + v.getbase() + "','" + v.getdate() + "');";
System.out.print("Your Database in : ");
try {
Class.forName(JDBC_DRIVER);
conn = DriverManager.getConnection(DB_URL,USERNAME,PASSWORD);
if (conn != null){System.out.println("good");}
else{System.out.println("bad");}
System.out.println(query);
stmt = conn.createStatement();
stmt.executeUpdate(query);
stmt.close();
conn.close();
} catch (ClassNotFoundException e) {
System.out.println("Class Not Found Exection");
} catch (SQLException e) {
System.out.println("SQL Exception : " + e.getMessage());
}
}
public void intertexc(int i, exc vw) {
}
}
excJSON.java
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
final static String apiKey = "tUxsDwwjT72GgMLoJRprXlqc34wmOzX4";
public exc getexc(boolean success, String timestamp, String base, String date, double GBP, double JPY, double EUR) {
String urlStr = "https://api.apilayer.com/exchangerates_data/latest?symbols=GBP%2CJPY%2CEUR&base=USD"
+ "&apiKey=" + apiKey + "&success=" + success + "&timestamp=" + timestamp
+ "&base="+ base + "&date=" + date + "&GBP=" + GBP + "&JPY=" + JPY + "&EUR=" + EUR + "&_type=json";
exc vl = new exc(); // 결과 데이터를 저장할 객체를 만듭니다.
try {
URL url = new URL(urlStr);
BufferedReader bf = new BufferedReader(new InputStreamReader(url.openStream()));
String line = "";
String result="";
while((line=bf.readLine())!=null){
result=result.concat(line);
}
//System.out.println(result);
JSONParser jsonParser = new JSONParser();
JSONObject jsonObj = (JSONObject) jsonParser.parse(result);
JSONObject parse_response = (JSONObject) jsonObj.get("response");
JSONObject obj;
String category;
vl.timestamp = timestamp;
vl.base = base;
vl.date = date;
for(int i = 0; i < parse_response.size(); i++) {
obj = (JSONObject) parse_response.get(i);
category = (String)obj.get("category");
switch(category) {
case "timestamp":
vl.timestamp = (obj.get("fcstValue")).toString();
break;
case "base":
vl.base = (obj.get("fcstValue")).toString();
break;
case "date":
vl.date = (obj.get("fcstValue")).toString();
break;
}
}
} catch (MalformedURLException e) {
System.out.println("MalformedURLException : " + e.getMessage());
} catch (IOException e) {
System.out.println("IOException : " + e.getMessage());
} catch (ParseException e) {
System.out.println("ParseException : " + e.getMessage());
}
return vl;
}
}
*Help me please. I think error in excJSON.java. I want make exchangerate program.
I want fix error.
error code : IOException : Server returned HTTP response code: 403 for URL: https://api.apilayer.com/exchangerates_data/latest?symbols=GBP%2CJPY%2CEUR&base=USD&apiKey=tUxsDwwjT72GgMLoJRprXlqc34wmOzX4&success=true&timestamp=1659072666&base=USD&date=2022-07-29&GBP=0.82011&JPY=133.000499&EUR=0.979105&_type=json
I assess "https://api.apilayer.com/exchangerates_data/latest?symbols=GBP%2CJPY%2CEUR&base=USD&apiKey=tUxsDwwjT72GgMLoJRprXlqc34wmOzX4&success=true&timestamp=1659072666&base=USD&date=2022-07-29&GBP=0.82011&JPY=133.000499&EUR=0.979105&_type=json"
but http say {"message":"No API key found in request"}
but i surely receive apikey and api.*

distance and duration between two point selected from google autocomplete using latitude and longitude in androidstudio

I am trying to get the distance between the points and because the places has no routes names it won't work.
This is the code that I am using
private void getPrice(String mLocation, String mDestination) {
String requestUrl= null;
try {
requestUrl = "https://maps.googleapis.com/maps/api/directions/json?"
+ "mode=driving&"
+"transit_routing_preference=less_driving&"
+ "origin="+mLocation+"&"
+"destination="+mDestination+"&"
+"key="+getResources().getString(R.string.google_browser_key);
Log.e("LINK",requestUrl);
mService.getPath(requestUrl).enqueue(new Callback<String>() {
#Override public void onResponse(Call<String> call, Response<String> response) {
try {
JSONObject jsonObject = new JSONObject(response.body().toString());
JSONArray routes = jsonObject.getJSONArray("routes");
JSONObject object = routes.getJSONObject(0);
JSONArray legs = object.getJSONArray("legs");
JSONObject legsObject = legs.getJSONObject(0);
JSONObject distance = legsObject.getJSONObject("distance");
String distance_text = distance.getString("text");
Double distance_value = Double.parseDouble(distance_text.replaceAll("[^0-9\\\\.]+",""));
JSONObject time = legsObject.getJSONObject("duration");
String time_text = time.getString("text");
Integer time_value = Integer.parseInt(time_text.replaceAll("\\D+",""));
String final_calculate = String.format("%s + %s = $%.2f",distance_text,time_text,
Common.getPrice(distance_value,time_value));
txtCalculate.setText(final_calculate);
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
public void onFailure(Call<String> call, Throwable t) {
Log.e("ERROR",t.getMessage());
}
});
}
catch (Exception ex) {
ex.printStackTrace();
}
}

cant decode a message from a Websocket

I`m trying to connect my HTML/JS client to my C# server as a part of a university project in order to allow the user real-time notification. (I just need the server to be able to send a specific user a message at any given time)
My server Is just a mock in order to implement it in my project.
I Successfully passed the handshake stage and I am trying to send a plain string from the server to the client. I read something about Encoding the message is a way that the client will not give the "One or more reserved bits are on: reserved1 = 0, reserved2 = 1, reserved3 = 1" error but without success.
How can I send primitive data through the Sockets and decode them on the client?
My server code:
while (true)
{
TcpListener sck = new TcpListener(IPAddress.Any, 7878);
sck.Start(1000);
TcpClient client = sck.AcceptTcpClient();
NetworkStream _stream = client.GetStream();
StreamReader clientStreamReader = new StreamReader(_stream);
StreamWriter clientStreamWriter = new StreamWriter(_stream);
while (true)
{
while (!_stream.DataAvailable) ;
Byte[] bytes = new Byte[client.Available];
_stream.Read(bytes, 0, bytes.Count());
String data = Encoding.UTF8.GetString(bytes);
if (Regex.IsMatch(data, "^GET"))
{
const string eol = "\r\n"; // HTTP/1.1 defines the sequence CR LF as the end-of-line marker
Byte[] response = Encoding.UTF8.GetBytes("HTTP/1.1 101 Switching Protocols" + eol
+ "Connection: Upgrade" + eol
+ "Upgrade: websocket" + eol
+ "Sec-WebSocket-Accept: " + Convert.ToBase64String(
System.Security.Cryptography.SHA1.Create().ComputeHash(
Encoding.UTF8.GetBytes(
new System.Text.RegularExpressions.Regex("Sec-WebSocket-Key: (.*)").Match(data).Groups[1].Value.Trim() + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
)
)
) + eol
+ eol);
_stream.Write(response, 0, response.Length);
}
else
{
}
}
}
My Client Code:
<script type="text/javascript">
function WebSocketTest() {
if ("WebSocket" in window) {
alert("WebSocket is supported by your Browser!");
// Let us open a web socket
var ws = new WebSocket("ws://localhost:7878");
ws.onopen = function () {
// Web Socket is connected, send data using send()
ws.send("Message to send");
alert("Message is sent...");
};
ws.onmessage = function (evt) {
var received_msg = evt.data;
alert("Message is received...");
};
ws.onclose = function () {
// websocket is closed.
alert("Connection is closed...");
};
} else {
// The browser doesn't support WebSocket
alert("WebSocket NOT supported by your Browser!");
}
}
</script>
I kept my server as above but added a send string function, and a decode message function:
public static string DecodeMessage(Byte[] bytes)
{
string incomingData = string.Empty;
byte secondByte = bytes[1];
int dataLength = secondByte & 127;
int indexFirstMask = 2;
if (dataLength == 126)
indexFirstMask = 4;
else if (dataLength == 127)
indexFirstMask = 10;
IEnumerable<byte> keys = bytes.Skip(indexFirstMask).Take(4);
int indexFirstDataByte = indexFirstMask + 4;
byte[] decoded = new byte[bytes.Length - indexFirstDataByte];
for (int i = indexFirstDataByte, j = 0; i < bytes.Length; i++, j++)
{
decoded[j] = (byte)(bytes[i] ^ keys.ElementAt(j % 4));
}
return Encoding.UTF8.GetString(decoded, 0, decoded.Length);
}
public static void SendString(string userName ,string str)
{
if (!userConnections.ContainsKey(userName))
return;
TcpClient client = userConnections[userName];
NetworkStream _stream = client.GetStream();
try
{
var buf = Encoding.UTF8.GetBytes(str);
int frameSize = 64;
var parts = buf.Select((b, i) => new { b, i })
.GroupBy(x => x.i / (frameSize - 1))
.Select(x => x.Select(y => y.b).ToArray())
.ToList();
for (int i = 0; i < parts.Count; i++)
{
byte cmd = 0;
if (i == 0) cmd |= 1;
if (i == parts.Count - 1) cmd |= 0x80;
_stream.WriteByte(cmd);
_stream.WriteByte((byte)parts[i].Length);
_stream.Write(parts[i], 0, parts[i].Length);
}
_stream.Flush();
}
catch (Exception ex)
{
Console.WriteLine("Error");
}
}
Where userConnections is: public static Dictionary userConnections = new Dictionary();
in order to maintain user - connection relation
You can use SuperWebSocket, this library sends the handshake automatically.
Server:
using SuperSocket.SocketBase;
using SuperWebSocket;
using System;
using System.Net;
using System.Net.Sockets;
namespace Jees.Library.WebSocket
{
public class WebSocket
{
WebSocketServer appServer;
public event EventHandler ServerStarted;
public event EventHandler ServerStopped;
public event EventHandler MessageReceived;
public string IP { get; } = string.Empty;
public int Port { get; } = 1337; //change this to the port you want to use
public WebSocket() => this.IP = GetLocalIPAddress(); //or set it manually
public void Start()
{
appServer = new WebSocketServer();
if (!appServer.Setup(this.IP, this.Port))
{
this.OnServerStarted(new WebSocketServerEventArgs(false));
return;
}
/* start listening */
appServer.NewMessageReceived += new SessionHandler<WebSocketSession, string>(AppServer_NewMessageReceived);
if (appServer.Start())
this.OnServerStarted(new WebSocketServerEventArgs(true));
else
{
this.OnServerStarted(new WebSocketServerEventArgs(false));
appServer = null;
appServer.Dispose();
}
}
public void Stop()
{
if (appServer != null)
{
appServer.Stop();
this.OnServerStopped(new EventArgs());
appServer = null;
appServer.Dispose();
}
}
private void AppServer_NewMessageReceived(WebSocketSession session, string message)
{
this.OnMessageReceived(new MessageReceivedEventArgs(message, session));
}
protected virtual void OnMessageReceived(EventArgs e) => this.MessageReceived?.Invoke(this, e);
protected virtual void OnServerStarted(EventArgs e) => this.ServerStarted?.Invoke(this, e);
protected virtual void OnServerStopped(EventArgs e) => this.ServerStopped?.Invoke(this, e);
private string GetLocalIPAddress()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
if (ip.AddressFamily == AddressFamily.InterNetwork)
return ip.ToString();
throw new Exception("No network adapters with an IPv4 address in the system!");
}
}
public class WebSocketServerEventArgs : EventArgs
{
public WebSocketServerEventArgs(bool success) => this.Success = success;
public bool Success { get; }
}
public class MessageReceivedEventArgs : EventArgs
{
public MessageReceivedEventArgs(string message, WebSocketSession session)
{
this.Message = message;
this.Session = session;
}
public string Message { get; }
public WebSocketSession Session { get; }
}
}
Server Setup (I use a UserControl):
using DevExpress.XtraEditors;
using SuperWebSocket;
using System;
using System.Linq;
using System.Windows.Forms;
namespace WebSocketServer
{
public partial class Server : UserControl
{
WebSocket server;
WebSocketSession session;
public Server()
{
InitializeComponent();
server = new WebSocket();
server.ServerStarted += Server_ServerStarted;
server.ServerStopped += Server_ServerStopped;
server.MessageReceived += Server_MessageReceived;
}
private void Server_MessageReceived(object sender, EventArgs e)
{
MessageReceivedEventArgs eventArgs = (MessageReceivedEventArgs)e;
/* save session */
this.session = eventArgs.Session;
this.Log("SessionID: " + session.RemoteEndPoint.ToString() + "; Message: " + eventArgs.Message);
/* send back the message to the client */
this.session.Send(eventArgs.Message); //comment out if needed
}
private void Server_ServerStopped(object sender, EventArgs e)
{
this.Log("Server stopped!");
}
private void Server_ServerStarted(object sender, EventArgs e)
{
if ((e as WebSocketServerEventArgs).Success)
{
this.Log("Server started on ws://" + server.IP + ":" + server.Port + "/");
}
else
this.Log("Can't start the server!");
}
private void Log(string message)
{
/* here, this.log is a TextBox */
if (this.log.InvokeRequired)
this.log.Invoke((MethodInvoker)delegate
{
this.log.Text += DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss") + " > " + message + Environment.NewLine;
});
else
{
this.log.Text += DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss") + " > " + message + Environment.NewLine;
}
}
/* a button to start the server */
private void BtnStart_Click(object sender, EventArgs e) => server.Start();
/* a button to stop the server */
private void BtnStop_Click(object sender, EventArgs e) => server.Stop();
/* a button to send a message from a TextBox to the client */
private void BtnSend_Click(object sender, EventArgs e)
{
if (this.txtMessage.Text != string.Empty)
this.SendMessage(this.txtMessage.Text);
}
private void SendMessage(string message)
{
try
{
/* use current session to send the message */
this.session.Send(message);
this.Log("Message: " + message + " sent to client!");
}
catch (Exception e)
{
this.Log(e.Message);
}
}
}
}
If you need more clarification, add a comment and I'll update my answer!

How to keep websocket alive

I am establishing websocket connectivity where server is built using javax.websocket and client is in JavaScript.
These code is working fine. But after some time session is closing. I want to keep this session alive.
I have two questions:
If this connection is getting closed because of session idle time
out
How to keep this session alive.
Following is the JavaScript code:
var wsUri="ws://localhost/";
var websocket = new WebSocket(wsUri);
var datasocket;
var username;
websocket.onopen = function(evt) { onOpen(evt) };
websocket.onmessage = function(evt) { onMessage(evt) };
websocket.onerror = function(evt) { onError(evt) };
function join() {
username = textField.value;
websocket.send(username + " joined");
console.log("joined");
}
function send_message() {
websocket.send(username + ": " + textField.value);
}
function onOpen() {
console.log("connected to url");
websocket.send("Hello");
// writeToScreen("Connected to " + wsUri);
}
function onMessage(evt) {
var res = {};
console.log("onMessage: " + evt.data);
if (evt.data.indexOf("joined") != -1) {
} else {
datasocket=evt.data
//getLatestData();
res = JSON.parse(event.data);
$scope.Impact = res["Impact"];
$scope.Temperature = res["Temperature"];
$scope.Humidity = res["Humidity"];
}
}
function onError(evt) {
writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data);
}
function writeToScreen(message) {
// output.innerHTML += message + "<br>";
}
function onClose(evt)
{
console.log("Disconnected");
}
And Java code is following:
#javax.websocket.server.ServerEndpoint("/")
public class Endpoint {
private static Queue<Session> queue = new ConcurrentLinkedQueue<Session>();
static StringBuilder sb = null;
ByteArrayOutputStream bytes = null;
#OnMessage
public void onMessage(Session session, String msg) {
// provided for completeness, in out scenario clients don't send any msg.
try {
// System.out.println("received msg "+msg+" from "+session.getId());
sendAll(msg);
} catch (Exception e) {
e.printStackTrace();
}
}
private static void sendAll(String msg) {
JSONParser parser = new JSONParser();
Object obj = null ;
try {
obj = parser.parse(msg);
} catch (ParseException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
JSONObject jsonObject = (JSONObject) obj;
if (sb == null) {
sb = new StringBuilder();
}
sb.append(jsonObject.toString());
// System.out.println(jsonObject.toJSONString());
try {
/* Send the new rate to all open WebSocket sessions */
ArrayList<Session > closedSessions= new ArrayList<>();
for (Session session : queue) {
if(!session.isOpen()) {
System.err.println("Closed session: "+session.getId());
closedSessions.add(session);
}
else {
session.getBasicRemote().sendText(msg);
}
}
queue.removeAll(closedSessions);
// System.out.println("Sending "+msg+" to "+queue.size()+" clients");
} catch (Throwable e) {
e.printStackTrace();
}
sb = null;
}
#OnOpen
public void open(Session session) {
queue.add(session);
System.out.println("New session opened: "+session.getId());
}
#OnError
public void error(Session session, Throwable t) {
queue.remove(session);
System.err.println("Error on session "+session.getId());
}
#OnClose
public void closedConnection(Session session) {
queue.remove(session);
System.out.println("session closed: "+session.getId());
}
}
you can disable the timeout in the server using a negative number in the IdleTimout
session.setMaxIdleTimeout(-1)
Set the non-zero number of milliseconds before this session will be closed by the container if it is inactive, ie no messages are either sent or received. A value that is 0 or negative indicates the session will never timeout due to inactivity.

Java Program TextFile Issue

I have a program where a text file is read in and then each word in the file is outputted, followed by the # of times it is repeated throughout the file.
Use the following code.
import java.io.*;
class FileRead {
public static void main(String args[]) {
try {
// Open the file that is the first
// command line parameter
FileInputStream fstream = new FileInputStream("C:\\Users\\Desktop\\formate.txt");
// Get the object of DataInputStream
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;
//Read File Line By Line
while ((strLine = br.readLine()) != null) {
// Print the content on the console
System.out.println(strLine);
}
//Close the input stream
in.close();
} catch (Exception e) {//Catch exception if any
System.err.println("Error: " + e.getMessage());
}
}
}
Try this code:
public static void main(String[] args) throws Throwable
{
File inputFile = new File("input.txt");
File outputFile = new File("output.txt");
Scanner scanner = new Scanner(inputFile);
HashMap<String, Integer> count = new HashMap<String, Integer>();
while (scanner.hasNext())
{
String word = scanner.next();
if (count.containsKey(word))
{
count.put(word, count.get(word) + 1);
}
else
{
count.put(word, 1);
}
}
scanner.close();
BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile));
for (Entry<String, Integer> entry : count.entrySet())
{
writer.write("#" + entry.getKey() + " " + entry.getValue()+"\r\n");
}
writer.close();
}
This also, it is a lot simpler if You can't use HashMap or BufferedReader:
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.LinkedList;
import java.util.Scanner;
public class WordCounter
{
public static void main(String[] args) throws Throwable
{
File inputFile = new File("input.txt");
File outputFile = new File("output.txt");
Scanner scanner = new Scanner(inputFile);
LinkedList<Word> words = new LinkedList<Word>();
while (scanner.hasNext())
{
String word = scanner.next();
addWord(words, word);
}
scanner.close();
WriteToFile(outputFile, words);
}
private static void WriteToFile(File outputFile, LinkedList<Word> words) throws IOException
{
BufferedWriter writer = new BufferedWriter(new FileWriter(outputFile));
for (Word word : words)
{
writer.write("#" + word.getWord() + " " + word.getCount() + "\r\n");
}
writer.close();
}
private static void addWord(LinkedList<Word> words, String word)
{
for (Word aWord : words)
{
if (aWord.getWord().equals(word))
{
aWord.incrementCount();
return;
}
}
words.add(new Word(word, 1));
}
}
class Word
{
private String word;
private int count;
public Word(String word, int count)
{
this.word = word;
this.count = count;
}
public String getWord()
{
return word;
}
public void setWord(String word)
{
this.word = word;
}
public int getCount()
{
return count;
}
public void setCount(int count)
{
this.count = count;
}
public void incrementCount()
{
count++;
}
#Override
public String toString()
{
return "Word: " + word + " Count: " + count;
}
}

Categories

Resources