This is SSE(Server Sent Events) library for jetty.
- You can easily execute SSE with jetty. Even containers other than jetty can be executed if servlet 3.0 or later.
- This library is based on http://github.com/mariomac's servlet sse library.
It is licensed under MIT.
Maven
<dependency>
<groupId>org.riversun</groupId>
<artifactId>jetty-sse-helper</artifactId>
<version>1.0.0</version>
</dependency>This is a SSE demo.
- SSEServlet.java
@SuppressWarnings("serial")
public class SSEServlet extends HttpServlet {
private final SSEHelper mPushHelper = new SSEHelper();
/**
* When receiving a request from JavaScript, add the requesting client to the PUSH (broadcast) target list
*/
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("Added " + req + " to target to broadcast");
mPushHelper.addTarget(req);
}
/**
* Broadcast message when receiving POST request
*/
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String msgToSend = req.getParameter("message");
if (msgToSend != null && !msgToSend.isEmpty()) {
} else {
msgToSend = "No Message";
}
mPushHelper.broadcast("message", msgToSend);
resp.setContentType("text/plain; charset=UTF-8");
final PrintWriter out = resp.getWriter();
out.println("OK");
out.close();
}
}- StartServer.Java
public class StartServer {
public void start() {
final int port = 8080;
ServletContextHandler servletContextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
ServletHolder sh = servletContextHandler.addServlet(SSEServlet.class, "/sse");
sh.setAsyncSupported(true);
final HandlerList hnList = new HandlerList();
final ResourceHandler rh = new ResourceHandler();
rh.setResourceBase(System.getProperty("user.dir") + "/htdocs");
rh.setDirectoriesListed(false);
rh.setWelcomeFiles(new String[] { "index.html" });
rh.setCacheControl("no-store,no-cache,must-revalidate");
hnList.addHandler(rh);
hnList.addHandler(servletContextHandler);
final Server server = new Server(port);
server.setHandler(hnList);
try {
server.start();
System.out.println("Server started on port:" + port);
server.join();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
new StartServer().start();
}
}Place client html file to htdocs folder on root of working directory.
- sse.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>Server Sent Event(SSE) Example</h1>
- Receive PUSH message from server and show that message<br>
- You can do send PUSH message from form below.<br>
- You can receive message on another browser you will open.
<hr>
<h3>Message to PUSH</h3>
<input id="text_message" value="Test message">
<button id="send_message">Send PUSH Message</button>
(You can push enter to send)
<br>
<br>
<small>（You can receive the message below even if you open <a href="sse.html" target="_blank">another browser</a> or tab）</small>
<hr>
<h3>Message received as PUSH from server</h3>
<div id="messages"></div>
<script>
const eventSource = new EventSource('sse');//http://localhost:8080/sse
const msgContent = document.querySelector('#messages');
eventSource.addEventListener('message', (event) => {
console.info('SSE: ' + event.data);
msgContent.innerHTML += event.data + '<br>';
});
const msgText = document.querySelector('#text_message');
const msgPostBtn = document.querySelector('#send_message');
const funcSendData = (event) => {
sendData('sse', {message: msgText.value});
msgText.value='';
};
msgText.addEventListener('keypress', function (event) {
if (event.key === 'Enter') {
event.preventDefault();
funcSendData(event);
}
});
msgPostBtn.addEventListener('click', funcSendData);
function sendData(url, data) {
const XHR = new XMLHttpRequest();
let urlEncodedData = '';
const urlEncodedDataPairs = [];
let name;
for (name in data) {
urlEncodedDataPairs.push(encodeURIComponent(name) + '=' + encodeURIComponent(data[name]));
}
urlEncodedData = urlEncodedDataPairs.join('&').replace(/%20/g, '+');
XHR.addEventListener('load', function (event) {
});
XHR.addEventListener('error', function (event) {
});
XHR.open('POST', url);
XHR.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
XHR.send(urlEncodedData);
}
</script>
</body>
</html>