Call Asynchronous Servlet From AJAX

Call Asynchronous Servlet From AJAX - java

What I am trying to accomplish is not too complex, but I am having a bit of trouble as I am not well versed in AJAX.
When it is implemented, I will have a JSP that has a button which invokes an Asynchronous Servlet. The servlet will run a long running task and provide dynamic feedback to the user by adding rows to a table when parts of the task are completed.
Before I attempt to write the final version, I am doing a proof of concept to get an understanding of how this will work. However, I'm running into a snag. When I use an AJAX call upon clicking a button, the function works as expected when the call is to a regular synchronous servlet. However, as soon as I make the servlet asynchronous, the updates are not displayed.
Would anybody be able to provide some insight into what's going wrong?
My JSP looks like this:
<html>
<body>
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
$('#mybutton').click(function() {
$.get('someservlet', function(responseJson) {
$.each(responseJson, function(index, item) {
$('<ul>').appendTo('#somediv');
$('<li>').text(item.row1).appendTo('#somediv');
$('<li>').text(item.row2).appendTo('#somediv');
$('<li>').text(item.row3).appendTo('#somediv');
$('<li>').text(item.row4).appendTo('#somediv');
});
});
});
});
</script>
<p><button id="mybutton">Click to add things</button></p>
<div id="somediv"></div>
</body>
</html>
My Asynchronous Servlet doGet() method looks like this:
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
final AsyncContext asyncContext = request.startAsync();
final PrintWriter writer = response.getWriter();
asyncContext.setTimeout(10000);
asyncContext.start(new Runnable() {
#Override
public void run() {
for (int i = 0; i < 10; i++) {
List<Row> rows = new ArrayList<Row>();
rows.add(new Row(i, i + 1, i + 2, i + 3));
String json = new Gson().toJson(rows);
writer.write(json);
writer.flush();
log.info("Wrote to JSON: " + i);
try {
Thread.sleep(1000);
} catch (InterruptedException ex) {
}
}
asyncContext.complete();
}
});
Any thoughts? It seems like my AJAX call that occurs when I click the button only accepts a response from the main servlet thread. Perhaps I need to call a JavaScript function from the asynchronous write() calls? I'm just not sure how to do this or if this would be the correct method of execution.

have a look at
http://www.oracle.com/webfolder/technetwork/tutorials/obe/java/async-servlet/async-servlets.html

OK!
So, I figured it out. It's not quite as fancy as I would have liked it to be, but it works. And, it's just a proof of concept for implementing what I am working on. If anyone can provide further insight, I've love to be able to implement this using server push instead of polling.
Thoughts?
My JSP looks like this:
<html>
<head>
<script src="jquery-1.7.1.min.js" type="text/javascript" ></script>
<script>
$(document).ready(function() {
var prevDataLength;
var nextLine = 0;
var pollTimer;
$('#abutton').click(function() {
$(function(){
var x = new $.ajaxSettings.xhr();
x.open("POST", "someservlet");
handleResponseCallback = function(){
handleResponse(x);
};
x.onreadystatechange = handleResponseCallback;
pollTimer = setInterval(handleResponseCallback, 100);
x.send(null);
});
});
function handleResponse(http) {
if (http.readyState != 4 && http.readyState != 3)
return;
if (http.readyState == 3 && http.status != 200)
return;
if (http.readyState == 4 && http.status != 200) {
clearInterval(pollTimer);
}
while (prevDataLength != http.responseText.length) {
if (http.readyState == 4 && prevDataLength == http.responseText.length)
break;
prevDataLength = http.responseText.length;
var response = http.responseText.substring(nextLine);
var lines = response.split('\n');
nextLine = nextLine + response.lastIndexOf(']') + 1;
if (response[response.length-1] != ']')
lines.pop();
for (var i = 0; i < lines.length; i++) {
var line = $.parseJSON(lines[i]);
addToTable(line);
}
}
if (http.readyState == 4 && prevDataLength == http.responseText.length)
clearInterval(pollTimer);
}
function addToTable(JSONitem) {
$.each(JSONitem, function(index, item) {
$('<tr>').appendTo('#sometablebody')
.append($('<td>').text(item.name))
.append($('<td>').text(item.message))
.append($('<td>').text(item.number))
.append($('<td>').append($('<a>').attr('href', item.link).text('link')));
});
}
});
</script>
<title>Async Test</title>
</head>
<body>
<p><button id="abutton">Click to add things</button></p>
<div id="somediv">
<table border="1">
<thead>
<tr>
<td>Name</td>
<td>Message</td>
<td>Number</td>
<td>Link</td>
</tr>
</thead>
<tbody id="sometablebody"></tbody>
</table>
</div>
</body>
</html>
My Asynchronous Servlet doGet() method looks like this:
request.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);
final AsyncContext asyncContext = request.startAsync();
final PrintWriter writer = response.getWriter();
asyncContext.setTimeout(60000);
asyncContext.start(new Runnable() {
#Override
public void run() {
for (int i = 0; i < 10; i++) {
try {
List<Row> list = new ArrayList<Row>();
list.add(new Row("First", "This is the first", String.valueOf(i), "link" + i));
list.add(new Row("Second", "This is the second", String.valueOf(i), "link" + i));
list.add(new Row("Third", "This is the third", String.valueOf(i), "link" + i));
String json = new Gson().toJson(list);
asyncContext.getResponse().setContentType("application/json");
asyncContext.getResponse().setCharacterEncoding("UTF-8");
try {
asyncContext.getResponse().getWriter().write(json);
asyncContext.getResponse().getWriter().flush();
} catch (IOException ex) {
System.out.println("fail");
}
Thread.sleep(250);
} catch (InterruptedException ex) {
break;
}
}
asyncContext.complete();
}
});
Additionally, for this all to work, I implemented a simple Row class:
public class Row {
private String name;
private String message;
private String number;
private String link;
public Row(String name, String message, String number, String link) {
setName(name);
setMessage(message);
setNumber(number);
setLink(link);
}
public String getLink() {
return link;
}
public void setLink(String link) {
this.link = link;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getNumber() {
return number;
}
public void setNumber(String number) {
this.number = number;
}
}

Related

Streaming Microphone from Javascript to Java. Unable to convert float 32 array to audio file

I am streaming the audio from microphone using javascript and sending the audio stream from frontend to backend via websocket. In my websocket handle message i can see float array recieving from front end but as soon as i write the float array to a file it does contatin any audio. here is link of generated audio file.
#Override
public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {
// TODO Auto-generated method stub
byte [] bb =getByteArrayFromByteBuffer((ByteBuffer)message.getPayload());
System.out.println(Arrays.toString(bb));
FileUtils.writeByteArrayToFile(file,bb,true);
}
private static byte[] getByteArrayFromByteBuffer(ByteBuffer byteBuffer) {
byte[] bytesArray = new byte[byteBuffer.remaining()];
byteBuffer.get(bytesArray, 0, bytesArray.length);
return bytesArray;
}
below is javascript streaming code:
<%# page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<button onclick="stop()">stop</button>
<script>
const AudioContext = window.AudioContext// Safari and old versions of Chrome
var context;
var source;
var bufferDetectorNode ;
jssocket= new WebSocket("ws://localhost:8080/websocket/name?user_id="+ generateRandomInteger(0, 3));
jssocket.onopen = function(e) {
console.log("[open] Connection established");
};
jssocket.onmessage = function(event) {
console.log(`[message] Data received from server: ${event.data}`);
};
jssocket.onclose = function(event) {
if (event.wasClean) {
console.log(`[close] Connection closed cleanly, code=${event.code} reason=${event.reason}`);
} else {
// e.g. server process killed or network down
// event.code is usually 1006 in this case
console.log('[close] Connection died');
}
};
jssocket.onerror = function(error) {
console.log(`[error] ${error.message}`);
};
try {
navigator.getUserMedia = navigator.getUserMedia
|| navigator.webkitGetUserMedia
|| navigator.mozGetUserMedia;
microphone = navigator.getUserMedia({
audio : true,
video : false
}, onMicrophoneGranted, onMicrophoneDenied);
} catch (e) {
alert(e)
}
async function onMicrophoneGranted(stream) {
console.log(stream)
context = new AudioContext();
source = context.createMediaStreamSource(stream);
await context.audioWorklet.addModule('/assets/js/buffer-detector.js');
// Create our custom node.
bufferDetectorNode= new AudioWorkletNode(context, 'buffer-detector');
bufferDetectorNode.port.onmessage = (event) => {
// Handling data from the processor.
jssocket.send(event.data)
// const byteArr = Int8Array.from(event.data)
//const original = Array.from(byteArr)
// console.log(original);
// jssocket.send( Buffer.from(byteArr, 'base64').toString('utf8'));
};
source.connect(bufferDetectorNode);
bufferDetectorNode.connect(context.destination);
//source.connect(context.destination);
}
function _base64ToArrayBuffer(base64) {
var binary_string = window.atob(base64);
var len = binary_string.length;
var bytes = new Uint8Array(len);
for (var i = 0; i < len; i++) {
bytes[i] = binary_string.charCodeAt(i);
}
return bytes.buffer;
}
function onMicrophoneDenied() {
console.log('denied')
}
function stop(){
bufferDetectorNode.disconnect(context.destination)
source.disconnect(bufferDetectorNode)
}
function generateRandomInteger(min, max) {
return Math.floor(min + Math.random() * (max - min + 1))
}
</script>
</body>
</html>
AudioWorklet
class BufferProcessor extends AudioWorkletProcessor {
bufferSize = 256
_bytesWritten = 0
// 2. Create a buffer of fixed size
_buffer = new Float32Array(this.bufferSize)
initBuffer() {
this._bytesWritten = 0
}
isBufferEmpty() {
return this._bytesWritten === 0
}
isBufferFull() {
return this._bytesWritten === this.bufferSize
}
process (inputs) {
this.append(inputs[0][0])
return true;
}
append(channelData) {
if (this.isBufferFull()) {
this.flush()
}
if (!channelData) return
for (let i = 0; i < channelData.length; i++) {
this._buffer[this._bytesWritten++] = channelData[i]
}
}
flush() {
// trim the buffer if ended prematurely
this.port.postMessage(
this._bytesWritten < this.bufferSize
? this._buffer.slice(0, this._bytesWritten)
: this._buffer
)
this.initBuffer()
}
static get parameterDescriptors() {
return [{
name: 'Buffer Detector',
}]
}
constructor() {
super();
this._socket = null;
this._isRecording = true;
this.initBuffer()
}
get socket() {
return this._socket;
}
set socket(value) {
if (value instanceof WebSocket) {
this._socket = value;
}
}
get recording() {
return this._isRecording;
}
set recording(value) {
if ('boolean' === typeof value) {
this._isRecording = value;
}
}
}
registerProcessor('buffer-detector',BufferProcessor );

copy text from dynamic webpage to a string

website looks somewhat like this:
dynamic webpage
i need to copy all text from a dynamic webpage[keeps changeing for each second like there is a countdown/loading] for each second to a string
previously i tried this code,
private class BackTask extends AsyncTask<String, Integer, String> {
#Override
protected void onPreExecute() {}
protected String doInBackground(String... address) {
String output = "";
try {
java.net.URL url = new java.net.URL(address[0]);
java.io.BufferedReader in = new java.io.BufferedReader(new java.io.InputStreamReader(url.openStream()));
String line;
while ((line = in.readLine()) != null) {
output += line;
}
in.close(); } catch (java.net.MalformedURLException e) {
output = e.getMessage();
} catch (java.io.IOException e) {
output = e.getMessage();
} catch (Exception e) {
output = e.toString();
}
return output;
}
protected void onProgressUpdate(Integer... values) {}
protected void onPostExecute(String s){
textview1.setText(s); }
it only gives source code of webpage
and it only works on static webpage
what that code gives me is :
<html>
<body>
<p id="demo"></p>
<script>
var myVar = setInterval(myTimer, 1000);
function myTimer() {
var d = new Date();
document.getElementById("demo").innerHTML = d.toLocaleTimeString();
}
</script>
</body>
</html>
but, what i need i need is just
17:07:24
i know Timer on Java.Utils
but what i need is just to copy all text from a webview/webpage and assign it to a string,
like, go to a random webpage > SELECT ALL > COPY > and PASTE it on notepad [manually]

Two ways you can render values on a webpage
Assign backend values to a JavaScript object or use expression language.
For reference go throw this link https://www.baeldung.com/spring-expression-language

How to get data from action class to jsp using ajax in struts2?

I'm new on ajax and want to get data from action class to jsp.
File : getRole.jsp
<head>
<script type="text/javascript">
var request;
function loaddata()
{
var id = document.getElementById("newRole").value;
alert("hi : "+ id);
var xhttp;
xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("display_info").innerHTML = this.responseText;
}
};
xhttp.open("GET", "loadData?id="+id, true);
xhttp.send();
}
</script>
</head>
<body>
<div class="container-fluid">
<div class="col-sm-2"></div>
<div class="col-sm-8">
<label for="focusedInput" id="abc"><h4>Enter Id : </h4></label>
<input type="text" class="form-control" name="newRole" id="newRole" onkeyup="loaddata();">
<div id="display_info" ></div>
</div>
<div class="col-sm-2"></div>
</div>
</body>
File : loadData.java
public class loadData extends ActionSupport implements ServletRequestAware, ServletResponseAware{
private static final long serialVersionUID = 1L;
String url = "jdbc:mysql://localhost:3306/struts";
String user = "username";
String pass = "password";
HttpServletRequest request;
HttpServletResponse response;
#Override
public void setServletRequest(HttpServletRequest request) {
// TODO Auto-generated method stub
this.request = request;
}
public HttpServletRequest getServletRequest() {
return request;
}
#Override
public void setServletResponse(HttpServletResponse response) {
// TODO Auto-generated method stub
this.response = response;
}
public HttpServletResponse getServletResponse()
{
return response;
}
public String execute()
{
try{
String id = request.getParameter("id");
String name = "null.";
System.out.println("in servlet : " + id);
Class.forName("com.mysql.jdbc.Driver");
java.sql.Connection con =DriverManager.getConnection(url, user, pass);
String s = "select * from tempemp where id="+id;
Statement st = con.createStatement();
ResultSet rs = st.executeQuery(s);
while(rs.next())
{
name = rs.getString("role");
System.out.println(name);
}
PrintWriter out = response.getWriter();
out.println("Name: "+name);
con.close();
}
catch(Exception e){
e.printStackTrace();
}
return SUCCESS;
}
}
I want to get Id from the user and then print role based on that Id.
I only want to use ajax not json. So please answer me only ajax code.

You have to return null in the action instead of success.
Returning null will do no further processing it will just send present response to the client.
Returning SUCCESS will search for specific jsp page defined for that result in struts.xml file.
this.responseText You will get your name.
For More reference https://struts.apache.org/docs/ajax.html

Post Issue with the JSP and Servlet?

I want to create a small quiz app in jsp which will ask the questions which are stored in the array. It should ask the ask until the last index of array. Here answer is also stored in the array. What I have done so far is:
Main Servlet
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try (PrintWriter out = response.getWriter()) {
session = request.getSession(true);
Quiz quiz = new Quiz();
if (session.isNew()) {
quiz.setTotalCorrectAnswers(0);
quiz.setCounter(0);
question = quiz.getNextQuestion(0);
answer = quiz.getAnswer(0);
}
session.setAttribute("quizes", quiz);
request.setAttribute("quiz", quiz);
request.setAttribute("currentQuestion", question);
request.setAttribute("error", false);
RequestDispatcher view = request.getRequestDispatcher("quiz.jsp");
view.forward(request, response);
} catch (Exception e) {
e.printStackTrace();
}
}
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try (PrintWriter out = response.getWriter()) {
String userAnswer = request.getParameter("txtAnswer");
Quiz quiz = (Quiz) session.getAttribute("quizes");
boolean error = false;
if (userAnswer.equals(quiz.getAnswer(quiz.getCounter()))) {
totalQuestions++;
quiz.setTotalCorrectAnswers(totalQuestions);
quiz.setCounter(quiz.getCounter() + 1);
session.setAttribute("nextQuestion", quiz.getCounter() + 1);
} else {
quiz.setTotalCorrectAnswers(totalQuestions);
quiz.setCounter(quiz.getCounter());
error = true;
}
session.setAttribute("quizes", quiz);
if(quiz.getTotalCorrectAnswers()>=5){
session.invalidate();
generateQuizOverPage(out);
}else{
request.setAttribute("quiz", quiz);
request.setAttribute("currentQuestion", quiz.getNextQuestion(quiz.getCounter()));
request.setAttribute("error", error);
RequestDispatcher view = request.getRequestDispatcher("quiz.jsp");view.forward(request, response);
}
} catch (Exception e) {
e.printStackTrace();
}
}
The Quiz model
String[] numberSeries = {
"3, 1, 4, 1, 5, ",
"1, 1, 2, 3, 5, ",
"1, 4, 9, 16, 25, ",
"2, 3, 5, 7, 11, ",
"1, 2, 4, 8, 16, "
};
String[] answer = {"9", "8", "36", "13", "32"};
private int counter;
private boolean isCorrect;
private int totalCorrectAnswers;
public Quiz() {
counter = 0;
isCorrect = false;
totalCorrectAnswers = 0;
}
public int getCounter() {
return counter;
}
public void setCounter(int counter) {
this.counter = counter;
}
public boolean isIsCorrect() {
return isCorrect;
}
public void setIsCorrect(boolean isCorrect) {
this.isCorrect = isCorrect;
}
public int getTotalCorrectAnswers() {
return totalCorrectAnswers;
}
public void setTotalCorrectAnswers(int totalCorrectAnswers) {
this.totalCorrectAnswers = totalCorrectAnswers;
}
public String getNextQuestion(int index) {
return numberSeries[index];
}
public String getAnswer(int index) {
return answer[index];
}
and the quiz.jsp file:
<%#page import="com.app.numberquiz.models.Quiz"%>
<%#page contentType="text/html" pageEncoding="UTF-8"%>
<%
Quiz quiz = (Quiz) request.getAttribute("quiz");
String currQuest = (String) request.getAttribute("currentQuestion");
Boolean error = (Boolean) request.getAttribute("error");
%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<form method='post'>
<h3>Have fun with NumberQuiz!</h3>
<p>Your current score is:
<% out.print(quiz.getTotalCorrectAnswers()); %> </br></br>
<p>Guess the next number in the sequence! </p>
<p>["<% out.print(currQuest); %><span style='color:red'>?</span>"]</p>
<p>Your answer:<input type='text' name='txtAnswer' value='' /></p>
<% if (error) { %>
<p style='color:red'>Your last answer was not correct! Please try again</p>
<% } %>
<p><input type='submit' name='btnNext' value='Next' /></p>
</form>
</body>
</html>
In the first run it shows the view correctly but when I reload the page it start to show null in the currQues in the view is it a problem in session if yes then where i have done wrong can anyone please explain it to me thank you!!

When you reload the page doGet method will work, you are setting question if the session is newly created and you put it in request. So when you reload your page session is not newly created and your currentQuestion is not set. You schould add an else case and assign the question or you should put these variables also in your session and retrieve it from the session in your jsp.

Spring Boot embedded HornetQ cluster not forwarding messages

I'm trying to create a static cluster of two Spring Boot applications with embedded HornetQ servers. One application/server will be handling external events and generating messages to be sent to a message queue. The other application/server will be listening on the message queue and process incoming messages. Because the link between the two applications is unreliable, each will use only local/inVM clients to produce/consume messages on their respective server, and relying on the clustering functionality to forward the messages to the queue on the other server in the cluster.
I'm using the HornetQConfigurationCustomizer to customize the embedded HornetQ server, because by default it only comes with an InVMConnectorFactory.
I have created a couple of sample applications that illustrate this setup, throughout this example "ServerSend", refers to the server that will be producing messages, and "ServerReceive" refers to the server that will be consuming messages.
pom.xml for both applications contains:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-hornetq</artifactId>
</dependency>
<dependency>
<groupId>org.hornetq</groupId>
<artifactId>hornetq-jms-server</artifactId>
</dependency>
DemoHornetqServerSendApplication:
#SpringBootApplication
#EnableScheduling
public class DemoHornetqServerSendApplication {
#Autowired
private JmsTemplate jmsTemplate;
private #Value("${spring.hornetq.embedded.queues}") String testQueue;
public static void main(String[] args) {
SpringApplication.run(DemoHornetqServerSendApplication.class, args);
}
#Scheduled(fixedRate = 5000)
private void sendMessage() {
String message = "Timestamp from Server: " + System.currentTimeMillis();
System.out.println("Sending message: " + message);
jmsTemplate.convertAndSend(testQueue, message);
}
#Bean
public HornetQConfigurationCustomizer hornetCustomizer() {
return new HornetQConfigurationCustomizer() {
#Override
public void customize(Configuration configuration) {
String serverSendConnectorName = "server-send-connector";
String serverReceiveConnectorName = "server-receive-connector";
Map<String, TransportConfiguration> connectorConf = configuration.getConnectorConfigurations();
Map<String, Object> params = new HashMap<String, Object>();
params.put(TransportConstants.HOST_PROP_NAME, "localhost");
params.put(TransportConstants.PORT_PROP_NAME, "5445");
TransportConfiguration tc = new TransportConfiguration(NettyConnectorFactory.class.getName(), params);
connectorConf.put(serverSendConnectorName, tc);
Set<TransportConfiguration> acceptors = configuration.getAcceptorConfigurations();
tc = new TransportConfiguration(NettyAcceptorFactory.class.getName(), params);
acceptors.add(tc);
params = new HashMap<String, Object>();
params.put(TransportConstants.HOST_PROP_NAME, "localhost");
params.put(TransportConstants.PORT_PROP_NAME, "5446");
tc = new TransportConfiguration(NettyConnectorFactory.class.getName(), params);
connectorConf.put(serverReceiveConnectorName, tc);
List<String> staticConnectors = new ArrayList<String>();
staticConnectors.add(serverReceiveConnectorName);
ClusterConnectionConfiguration conf = new ClusterConnectionConfiguration(
"my-cluster", // name
"jms", // address
serverSendConnectorName, // connector name
500, // retry interval
true, // duplicate detection
true, // forward when no consumers
1, // max hops
1000000, // confirmation window size
staticConnectors,
true // allow direct connections only
);
configuration.getClusterConfigurations().add(conf);
AddressSettings setting = new AddressSettings();
setting.setRedistributionDelay(0);
configuration.getAddressesSettings().put("#", setting);
}
};
}
}
application.properties (ServerSend):
spring.hornetq.mode=embedded
spring.hornetq.embedded.enabled=true
spring.hornetq.embedded.queues=jms.testqueue
spring.hornetq.embedded.cluster-password=password
DemoHornetqServerReceiveApplication:
#SpringBootApplication
#EnableJms
public class DemoHornetqServerReceiveApplication {
#Autowired
private JmsTemplate jmsTemplate;
private #Value("${spring.hornetq.embedded.queues}") String testQueue;
public static void main(String[] args) {
SpringApplication.run(DemoHornetqServerReceiveApplication.class, args);
}
#JmsListener(destination="${spring.hornetq.embedded.queues}")
public void receiveMessage(String message) {
System.out.println("Received message: " + message);
}
#Bean
public HornetQConfigurationCustomizer hornetCustomizer() {
return new HornetQConfigurationCustomizer() {
#Override
public void customize(Configuration configuration) {
String serverSendConnectorName = "server-send-connector";
String serverReceiveConnectorName = "server-receive-connector";
Map<String, TransportConfiguration> connectorConf = configuration.getConnectorConfigurations();
Map<String, Object> params = new HashMap<String, Object>();
params.put(TransportConstants.HOST_PROP_NAME, "localhost");
params.put(TransportConstants.PORT_PROP_NAME, "5446");
TransportConfiguration tc = new TransportConfiguration(NettyConnectorFactory.class.getName(), params);
connectorConf.put(serverReceiveConnectorName, tc);
Set<TransportConfiguration> acceptors = configuration.getAcceptorConfigurations();
tc = new TransportConfiguration(NettyAcceptorFactory.class.getName(), params);
acceptors.add(tc);
params = new HashMap<String, Object>();
params.put(TransportConstants.HOST_PROP_NAME, "localhost");
params.put(TransportConstants.PORT_PROP_NAME, "5445");
tc = new TransportConfiguration(NettyConnectorFactory.class.getName(), params);
connectorConf.put(serverSendConnectorName, tc);
List<String> staticConnectors = new ArrayList<String>();
staticConnectors.add(serverSendConnectorName);
ClusterConnectionConfiguration conf = new ClusterConnectionConfiguration(
"my-cluster", // name
"jms", // address
serverReceiveConnectorName, // connector name
500, // retry interval
true, // duplicate detection
true, // forward when no consumers
1, // max hops
1000000, // confirmation window size
staticConnectors,
true // allow direct connections only
);
configuration.getClusterConfigurations().add(conf);
AddressSettings setting = new AddressSettings();
setting.setRedistributionDelay(0);
configuration.getAddressesSettings().put("#", setting);
}
};
}
}
application.properties (ServerReceive):
spring.hornetq.mode=embedded
spring.hornetq.embedded.enabled=true
spring.hornetq.embedded.queues=jms.testqueue
spring.hornetq.embedded.cluster-password=password
After starting both applications, log output shows this:
ServerSend:
2015-04-09 11:11:58.471 INFO 7536 --- [ main] org.hornetq.core.server : HQ221000: live server is starting with configuration HornetQ Configuration (clustered=true,backup=false,sharedStore=true,journalDirectory=C:\Users\****\AppData\Local\Temp\hornetq-data/journal,bindingsDirectory=data/bindings,largeMessagesDirectory=data/largemessages,pagingDirectory=data/paging)
2015-04-09 11:11:58.501 INFO 7536 --- [ main] org.hornetq.core.server : HQ221045: libaio is not available, switching the configuration into NIO
2015-04-09 11:11:58.595 INFO 7536 --- [ main] org.hornetq.core.server : HQ221043: Adding protocol support CORE
2015-04-09 11:11:58.720 INFO 7536 --- [ main] org.hornetq.core.server : HQ221003: trying to deploy queue jms.queue.jms.testqueue
2015-04-09 11:11:59.568 INFO 7536 --- [ main] org.hornetq.core.server : HQ221020: Started Netty Acceptor version 4.0.13.Final localhost:5445
2015-04-09 11:11:59.593 INFO 7536 --- [ main] org.hornetq.core.server : HQ221007: Server is now live
2015-04-09 11:11:59.593 INFO 7536 --- [ main] org.hornetq.core.server : HQ221001: HornetQ Server version 2.4.5.FINAL (Wild Hornet, 124) [c139929d-d90f-11e4-ba2e-e58abf5d6944]
ServerReceive:
2015-04-09 11:12:04.401 INFO 4528 --- [ main] org.hornetq.core.server : HQ221000: live server is starting with configuration HornetQ Configuration (clustered=true,backup=false,sharedStore=true,journalDirectory=C:\Users\****\AppData\Local\Temp\hornetq-data/journal,bindingsDirectory=data/bindings,largeMessagesDirectory=data/largemessages,pagingDirectory=data/paging)
2015-04-09 11:12:04.410 INFO 4528 --- [ main] org.hornetq.core.server : HQ221045: libaio is not available, switching the configuration into NIO
2015-04-09 11:12:04.520 INFO 4528 --- [ main] org.hornetq.core.server : HQ221043: Adding protocol support CORE
2015-04-09 11:12:04.629 INFO 4528 --- [ main] org.hornetq.core.server : HQ221003: trying to deploy queue jms.queue.jms.testqueue
2015-04-09 11:12:05.545 INFO 4528 --- [ main] org.hornetq.core.server : HQ221020: Started Netty Acceptor version 4.0.13.Final localhost:5446
2015-04-09 11:12:05.578 INFO 4528 --- [ main] org.hornetq.core.server : HQ221007: Server is now live
2015-04-09 11:12:05.578 INFO 4528 --- [ main] org.hornetq.core.server : HQ221001: HornetQ Server version 2.4.5.FINAL (Wild Hornet, 124) [c139929d-d90f-11e4-ba2e-e58abf5d6944]
I see clustered=true in both outputs, and this would show false if I removed the cluster configuration from the HornetQConfigurationCustomizer, so it must have some effect.
Now, ServerSend shows this in the console output:
Sending message: Timestamp from Server: 1428574324910
Sending message: Timestamp from Server: 1428574329899
Sending message: Timestamp from Server: 1428574334904
However, ServerReceive shows nothing.
It appears that the messages are not forwarded from ServerSend to ServerReceive.
I did some more testing, by creating two further Spring Boot applications (ClientSend and ClientReceive), which do not have a HornetQ server embedded and instead connect to a "native" server.
pom.xml for both client applications contains:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-hornetq</artifactId>
</dependency>
DemoHornetqClientSendApplication:
#SpringBootApplication
#EnableScheduling
public class DemoHornetqClientSendApplication {
#Autowired
private JmsTemplate jmsTemplate;
private #Value("${queue}") String testQueue;
public static void main(String[] args) {
SpringApplication.run(DemoHornetqClientSendApplication.class, args);
}
#Scheduled(fixedRate = 5000)
private void sendMessage() {
String message = "Timestamp from Client: " + System.currentTimeMillis();
System.out.println("Sending message: " + message);
jmsTemplate.convertAndSend(testQueue, message);
}
}
application.properties (ClientSend):
spring.hornetq.mode=native
spring.hornetq.host=localhost
spring.hornetq.port=5446
queue=jms.testqueue
DemoHornetqClientReceiveApplication:
#SpringBootApplication
#EnableJms
public class DemoHornetqClientReceiveApplication {
#Autowired
private JmsTemplate jmsTemplate;
private #Value("${queue}") String testQueue;
public static void main(String[] args) {
SpringApplication.run(DemoHornetqClientReceiveApplication.class, args);
}
#JmsListener(destination="${queue}")
public void receiveMessage(String message) {
System.out.println("Received message: " + message);
}
}
application.properties (ClientReceive):
spring.hornetq.mode=native
spring.hornetq.host=localhost
spring.hornetq.port=5445
queue=jms.testqueue
Now the console shows this:
ServerReveive:
Received message: Timestamp from Client: 1428574966630
Received message: Timestamp from Client: 1428574971600
Received message: Timestamp from Client: 1428574976595
ClientReceive:
Received message: Timestamp from Server: 1428574969436
Received message: Timestamp from Server: 1428574974438
Received message: Timestamp from Server: 1428574979446
If I have ServerSend running for a while, and then start ClientReceive, it also receives all the messages queued up to that point, so this shows that the messages don't just disappear somewhere, or get consumed from somewhere else.
For completeness sake I've also pointed ClientSend to ServerSend and ClientReceive to ServerReceive, to see if there is some issue with clustering and the InVM clients, but again there was no outout indicating that any message was received in either ClientReceive or ServerReceive.
So it appears that message delivery to/from each of the embedded brokers to directly connected external clients works fine, but no messages are forwarded between brokers in the cluster.
So, after all this, the big question, what's wrong with the setup that messages aren't forwarded within the cluster?

http://docs.jboss.org/hornetq/2.2.5.Final/user-manual/en/html/architecture.html#d0e595
"HornetQ core is designed as a set of simple POJOs so if you have an application that requires messaging functionality internally but you don't want to expose that as a HornetQ server you can directly instantiate and embed HornetQ servers in your own application."
If you are embedding it, you aren't exposing it as a server. Each of your containers has a seperate instance. It is the equivalent of starting up 2 copies of hornet and giving them the same queue name. One writes to that queue on the first instance and the other listens to the queue on the second instance.
If you want to decouple your apps in this way, you need to have a single place that is acting as a server. Probably, you want to cluster. This isn't specific to Hornet, BTW. You'll find this pattern often.

FILTER
package it.unitn.disi.webdev.claudiovigliarolo;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
#WebFilter(filterName = "AuthenticationFilter", urlPatterns = { "/*" })
public class AuthenticationFilter implements Filter {
private ServletContext context;
public void init(FilterConfig fConfig) throws ServletException {
this.context = fConfig.getServletContext();
this.context.log("AuthenticationFilter initialized");
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
String uri = req.getRequestURI();
HttpSession session = req.getSession(false);
boolean isLoggedIn = session != null && session.getAttribute("username") != null;
if (!isLoggedIn && !uri.endsWith("start.jsp")) {
res.sendRedirect("start.jsp");
} else {
chain.doFilter(request, response);
}
}
public void destroy() {
// close any resources here
}
}<filter-mapping><filter-name>AuthenticationFilter</filter-name><url-pattern>/*</url-pattern>
</filter-mapping>
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
#WebServlet(name = "GetItems", urlPatterns = { "/GetItems" })
public class GetItems extends HttpServlet {
String dbURL = "jdbc:derby://localhost:1527/ExamDerbyDB";
String user = "WEBENGINE";
String password = "WEBENGINE";
Connection conn = null;
#Override
public void init() {
try {
Class.forName("org.apache.derby.jdbc.ClientDriver");
conn = DriverManager.getConnection(dbURL, user, password);
} catch (ClassNotFoundException | SQLException ex) {
ex.printStackTrace();
}
}
#Override
public void destroy() {
try {
if (conn != null) {
conn.close();
}
} catch (SQLException ex) {
System.err.println("Database connection problem: can't close connection");
}
}
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
StringBuilder ret = new StringBuilder();
ArrayList<String> inserted = getAllItemsFromDB();
String jsonResponse = getListJson(inserted);
response.setContentType("application/json;charset=UTF-8");
try (PrintWriter out = response.getWriter()) {
out.println(jsonResponse);
}
}
private ArrayList<String> getAllItemsFromDB() throws ServletException {
ArrayList elements = new ArrayList();
PreparedStatement stm = null;
ResultSet result = null;
try {
String query = "SELECT USERNAME FROM USERS";
stm = conn.prepareStatement(query);
result = stm.executeQuery();
while(result.next()) {
String string = result.getString(1);
elements.add(string);
}
stm.close();
result.close();
} catch (SQLException ex) {
System.err.println("Database connection problem");
} finally {
try {
if(stm != null) stm.close();
if(result != null) result.close();
} catch (SQLException ex) {
System.err.println("Database connection problem: can't close statement/result");
}
return elements;
}
public String getListJson(ArrayList<String> list) {
if (list.size() == 0)
return null;
StringBuilder ret = new StringBuilder("[");
String prefix = "";
for (int i = 0; i < list.size(); i++) {
StringBuilder sb = new StringBuilder();
ret.append(prefix);
prefix = ",";
ret.append(sb.append("{\"message\":\"").append(list.get(i)).append("\"}").toString());
}
ret.append("]");
return ret.toString();
}
}
class.java
public class MessageList {
protected final LinkedList<Message> list;
public MessageList() {
this.list = new LinkedList<>();
}
public void addMessage(Message m) {
this.list.add(m);
}
public void deleteMessage(String message_id) {
for (Message a : list) {
if (a.message_id.equals(message_id)) {
list.remove(a);
}
}
}
public Message getMessage(String message_id) {
for (Message a : list) {
if (a.message_id.equals(message_id)) {
return a;
}
}
return null;
}
public void addLike(String message_id) {
for (Message a : list) {
if (a.message_id.equals(message_id)) {
a.isLiked++;
}
}
}
StringBuilder ret = new StringBuilder("[");
String prefix = "";for(
int i = 0;i<list.size();i++)
{
Message m = list.get(i);
ret.append(prefix);
prefix = ",";
ret.append(m.toJson());
}ret.append("]");
return ret.toString();
}
public String getListJson()
{
if(list.size() == 0)
{
return null;
}
StringBuilder ret = new StringBuilder("[");
String prefix = "";
for(int i=0; i<list.size(); i++) {
StringBuilder sb = new StringBuilder();
ret.append(prefix);
prefix = ",";
ret.append(sb.append("{\"message\":\"").append(list.get(i)).append("\"}").toString());
}
ret.append("]");
return ret.toString();
}
}
form
<!DOCTYPE html>
<html lang="en">
<body>
<script>
function validateForm(form) {
var username = document.getElementById("username").value;
var password = document.getElementById("password").value;
var error = document.getElementById("error");
error.innerHTML = "";
if (username === "" || password == "") {
form.reset();
error.innerHTML = "password / username empty";
return false;
}
return true;
}
</script>
<div class="container" style="width: 500px; float: left">
<h2 class="text-center">Welcome to the App</h2>
<form
id="registerForm"
method="POST"
onsubmit="return validateForm(this)"
action="Registration"
>
<div class="form-group">
<label for="username">Username:</label>
<input
type="text"
class="form-control"
id="username"
placeholder="Enter email"
name="username"
/>
</div>
<div class="form-group">
<label for="password">Password:</label>
<input
type="password"
class="form-control"
id="password"
placeholder="Enter password"
name="password"
/>
</div>
<div class="form-group form-check"></div>
<button type="submit" class="btn btn-primary">Submit</button>
</form>
<div id="error" class="alert" role="alert"></div>
</div>
</body>
</html>
general
//servelet context
ServletContext application=getServletContext();
application.setAttribute("messages", messages);
//SESSION
HttpSession session = request.getSession();
String name = (String) request.getParameter("username");
session.setAttribute("username", name);
//random id java
String uniqueID = UUID.randomUUID().toString();
//package
it.unitn.disi.webdev.claudiovigliarolo
//project name
VIGLIAROLO_C_202314
//get contextpath
String contextPath = request.getContextPath();
System.out.println("Context Path = " + contextPath);
response.sendRedirect(contextPath + "/main.html");
//BOOTstrap
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
</head>
//redirect to other page
window.location.replace("http://stackoverflow.com");
//CONTENT type
response.setContentType("application/json;charset=UTF-8");
response.setContentType("text/html;charset=UTF-8");
//zuccherino
protected final LinkedList<Message> list;
public MessageList() {
this.list = new LinkedList<>();
}
<!DOCTYPE html>
<html lang="en">
<body>
<script>
function validateForm(form) {
var username = document.getElementById("username").value;
var password = document.getElementById("password").value;
var error = document.getElementById("error");
error.innerHTML = "";
if(username === "" || password == "") {
form.reset();
error.innerHTML = "password / username empty";
return false;
}
return true;
}
</script>
<div class="container " style="width:500px; float: left;">
<h2 class="text-center">Welcome to the App</h2>
<form id="registerForm" method="POST" onsubmit="return validateForm(this)" action="Registration">
<div class="form-group">
<label for="username">Username:</label>
<input type="text" class="form-control" id="username" placeholder="Enter email" name="username">
</div>
<div class="form-group">
<label for="password">Password:</label>
<input type="password" class="form-control" id="password" placeholder="Enter password" name="password">
</div>
<div class="form-group form-check">
</div>
<button type="submit" class="btn btn-primary">Submit</button>
</form>
<div id="error" class="alert" role="alert">
</div>
</div>
</body>
</html>
//change styles
const val = keywords.some(k=>item.message.includes(k));
const color = val ? "#FFFF00;" : "transparent;";
document.getElementById("data").innerHTML +=
"<div style=' margin-top:50px;flexdirection: row; display:flex; width:500px; background:" + color + "; justify-content: row; '>" +
item.message +
"</div>";
//setimeout
function refresh() {
// make Ajax call here, inside the callback call:
setTimeout(refresh, 5000);
// ...
}
// initial call, or just call refresh directly
setTimeout(refresh, 5000);
//template strings
`string text`
getclaudio postclaudio
<script>
function onSendData() {
var title = document.getElementById("username").value;
var description = document.getElementById("password").value;
console.log(title, description);
var http = new XMLHttpRequest();
var url = "Registration";
var params = "password=" + description + "&username=" + title;
http.open("POST", url, true);
//Send the proper header information along with the request
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.onreadystatechange = function () {
//Call a function when the state changes.
if (http.readyState == 4 && http.status == 200) {
console.log("res", http.responseText);
}
};
http.send(params);
}
</script>
------GET---------------
//loadData noparam
<script>
loadData();
function loadData() {
var xhttp = new XMLHttpRequest();
xhttp.open("GET", "GetProducts", true);
xhttp.responseType = "json";
xhttp.onreadystatechange = function () {
var done = 4,
ok = 200;
if (this.readyState === done && this.status === ok) {
my_JSON_object = this.response;
console.log("response", my_JSON_object);
document.getElementById("data").innerHTML = "";
my_JSON_object && my_JSON_object.forEach((item) => {
console.log("item", item.message);
document.getElementById("data").innerHTML +=
" <div class='card' style='width: 300px; margin-top:50px;'>" +
"<div class='card-body'>" +
" <h4 class='card-title'>" + item.name + "</h4>" +
"<p class='card-text'>" + item.description + "</p>" +
" <p class='card-text'>Price: " + item.price + " $</p>" +
" <a href='detail.html?name=" + item.name + "' class='card-link' >View details</a>" +
" </div> </div>";
});
}
};
xhttp.send();
}
</script>
<div id="data"></div>
//loadData withparam
<script>
function getData() {
const urlParams = new URLSearchParams(window.location.search);
const id = urlParams.get('id');
const id2 = urlParams.get('id2');
console.log(id)
var url = "GetItems";
let param1 = id;
let param2 = id2;
var params = "param1=" + param1 + "&param2=" + param2;
var http = new XMLHttpRequest();
http.open("GET", url + "?" + params, true);
http.responseType = "json";
http.onreadystatechange = function () {
var done = 4,
ok = 200;
if (this.readyState === done && this.status === ok) {
my_JSON_object = this.response;
console.log("response", my_JSON_object);
document.getElementById("data").innerHTML = "";
my_JSON_object && my_JSON_object.forEach((item) => {
console.log("item", item.message);
document.getElementById("data").innerHTML +=
"<div style=' margin-top:50px;flexdirection: row; display:flex; width:500px; justify-content: row; '>" +
item.message +
"</div>";
});
}
};
http.send(null);
}
</script>
<div id="data"></div>
<div class="card" style="margin-top: 50px;">
<div class="card-body">Content</div>
</div>
//render multiple parameters
onclick="showData('${item.name}', '${item.price}', '${item.punteggio}', '${item.extra}' )"
JSON servelet claudio
RETURN JSON
//create simple json response
response.setContentType("application/json;charset=UTF-8");
StringBuilder ret = new StringBuilder();
ret.append("{\"ready\":\"").append("false").append("\"}");
try (PrintWriter out = response.getWriter()) {
out.println(ret.toString());
}
JSON LIST CLASS
public String toJSON() {
StringBuilder ret = new StringBuilder("[");
String prefix = "";
for(int i=0; i<list.size(); i++) {
Message m = list.get(i);
ret.append(prefix);
prefix = ",";
ret.append(m.toJson());
}
ret.append("]");
System.err.println("priting tojson"+ ret.toString());
return ret.toString();
}
JSON ITEM
public String toJson() {
StringBuilder ret = new StringBuilder();
ret.append("{\"id\":\"").append(this.id).append("\",");
ret.append("\"nome\":\"").append(this.nome).append("\",");
ret.append("\"imgName\":\"").append(this.imgName).append("\"}");
return ret.toString();
}
STRING LIST
public String wordsToJSON(ArrayList<String> list) {
System.err.println("lunghezza" + list.size());
if (list.size() == 0) {
return null;
}
StringBuilder ret = new StringBuilder("[");
String prefix = "";
for (int i = 0; i < list.size(); i++) {
StringBuilder sb = new StringBuilder();
ret.append(prefix);
prefix = ",";
ret.append(sb.append("{\"message\":\"").append(list.get(i)).append("\"}").toString());
}
ret.append("]");
System.err.println("jjj" + ret.toString());
return ret.toString();
}
}
JSON RESPONSE OK
ServletContext application=getServletContext();
MappaDiCoppie mappaDiCoppie = (MappaDiCoppie) application.getAttribute("mappaDiCoppie");
HttpSession session= request.getSession();
String username = (String) session.getAttribute("username");
StringBuilder ret = new StringBuilder();
if(mappaDiCoppie != null && username != null)
{
if(mappaDiCoppie.exists(username))
//ok
ret.append("{\"ready\":\"").append("true").append("\"}");
else
//no wait
ret.append("{\"ready\":\"").append("false").append("\"}")
try (PrintWriter out = response.getWriter()) {
out.println(ret.toString());
}
}
```

stylesheet
<link rel="stylesheet" href="./styles/styles.css">
<script type="text/javascript" src="./js/script.js"></script>
matrix html
const N = 9;
const container = document.getElementById("container");
function makeRows(rows, cols) {
container.style.setProperty('--grid-rows', rows);
container.style.setProperty('--grid-cols', cols);
for (c = 0; c < (cols); c++) {
for (r = 0; r < rows; r++) {
const myid = JSON.stringify({x: r, y: c});
let cell = document.createElement("div");
var textnode = document.createElement("span");
textnode.setAttribute("id", myid);
cell.appendChild(textnode);
cell.onclick = function (event) {
showVal(myid, r, c);
}
//cell.innerText = (c + 1);
container.appendChild(cell).className = "grid-item";
container.appendChild(cell).style = "border-color: red";
container.appendChild(cell).style = "border-width: 4px";
}
;
}
}
//styles
.myinput{
width: 50px;
margin-right: 20px;
}
#container {
display: grid;
grid-gap: .5em;
grid-template-rows: repeat(var(--grid-rows), 1fr);
grid-template-columns: repeat(var(--grid-cols), 1fr);
width: 100px;
}
.grid-item {
border: 1px solid #ddd;
text-align: center;
width: 50px;
height: 50px;
border-width: 2px;
border-color: green;
}
grid java
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package utils;
import java.util.ArrayList;
import java.util.Random;
/**
*
* #author claud
*/
public class Grid {
int N;
Cell[][] matrix;
public Grid(int N) {
this.N = N;
this.matrix = new Cell[N][N];
}
private int getRandom() {
Random rn = new Random();
int range = 0 - 0 + 1;
int randomNum = rn.nextInt(N) + 0;
return randomNum;
}
public int getValue(int x, int y) {
if (x < N && y < N) {
return this.matrix[x][y].value;
} else {
return -2;
}
}
public void generate() {
System.err.println("ffffffffffffggg");
//fai il ciclo completo
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
this.matrix[i][j] = new Cell(i, j, 0);//aggiungi bombe con random altrimenti valore 0
}
}
}
public void print() {
System.err.println("printiiiiiiiiiiiing START");
for (int i = 0; i < N; i++) {
for (int j = 0; j < N; j++) {
System.err.println(this.matrix[i][j].value);
}
}
}
}

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Java is a programming language and computing platform first released by Sun Microsystems in 1995.

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