Develop Reference

ending JVM when the browser tab is closed in spring boot application

I have a spring-boot web application to be distributed as jar file. The code to start the application is as follows:
private static ConfigurableApplicationContext ctx;
public static void main(String[] args){
if(ctx == null) {
ctx = SpringApplication.run(MyApplication.class, args);
}
try {
openHomePage("http://localhost:8090/");
}catch(Exception e) {
logger.error("Error occured starting the application: ", e);
ctx.close();
}
}
private static void openHomePage(String url) throws IOException, URISyntaxException {
if(Desktop.isDesktopSupported()) {
URI homePage = new URI(url);
Desktop.getDesktop().browse(homePage);
}else {
Runtime runtime = Runtime.getRuntime();
runtime.exec(new String[]{"cmd", "/c","start chrome " + url});
}
}
which opens the home page in Chrome, both when I run it from Eclipse and by double clicking on the jar file.
The problem is when I start the application from the jar file and close the browser tab, the application continues to run in JVM and I have to kill it from the task manager manually which is annoying. If I don't kill the JVM and double click on the jar file again, then the application doesn't start automatically as it does the first time, and I have to manually open a new browser tab and type http://localhost:8090/ in order to use the application.
Is it possible to kill every process after user closes the browser tab so that when they click on the jar file next time they need to use the application, a fresh browser tab opens automatically?
Thanks in advance..

SOLUTION
This might not be the best solution but it works a treat.
*Step 1 - Send heartbeats from the browser
var heartBeatIntervals = null;
$( document ).ready(function() {
//this ajax call will be fired every 2 seconds as long as the browser tab stays open.
// the time intervals can of course be modified
heartBeatIntervals = setInterval(() => {
$.ajax({
type:'POST',
url: 'http://localhost:8090/MyController/checkHeartbeats'
})
}, 2*1000);
});
*Step 2 - Handle the heartbeats in the server
#Controller
#RequestMapping("/MyController")
public class MyController {
//declare an instance variable to store the number of missed heartbeats
private int missedHeartbeats = 0;
//reset the counter to 0 upon receiving the heartbeats
#PostMapping("/checkHeartbeats")
public void checkHeartbeats() {
missedHeartbeats = 0;
}
//increase the missedHeartbeats by one every 3 seconds - or whatever
#Scheduled(fixedRate = 3000)
public void schedule() {
missedHeartbeats++;
//check how many heartbeats are missed and if it reaches to a certain value
if(missedHeartbeats > 5) {
//terminate the JVM (also terminates the servlet context in Eclipse)
System.exit(0);
}
}
}
*Step - 3 Enable scheduling
In order to use any scheduling in spring-boot application you need to add #EnableScheduling annotation in your class where your main method resides.
And that's it.

There's a stop button in Eclipse. And in case it can't be used:
You can send something from javascript to your server continiously and when server haven't recieved it for 1 sec, which means the web page was closed, stop itself.
Solution 1
Use a method in any #Controller to handle heartbeat requests.
Store the most recent heartbeat time in a static field of any class, the initial value could be 0 or -1 indicating the web page has not been opened yet.
Use a #Scheduled task to retrive last heartbeat time and compare with current time. schedule the task once per 2 second or whatever. https://docs.spring.io/spring/docs/3.2.x/spring-framework-reference/html/scheduling.html#scheduling-annotation-support
Stop JVM if needed, maybe by System.exit(0).
Solution 2
It would be easier if you can add a Close button on webpage. being clicked, it signals the server to stop, and afterwards it closes the web page itself. https://stackoverflow.com/a/18776480/9399618

How to kill the browser instance (chrome) that was opened by web driver previously

I want to kill the browser instance (chrome) that was opened by web driver previously. How would I do that? In my code below, I intentionally didn't want to include quit() or close() as I want to leave the browser open. So every time I execute or run this program, I want to kill/close the previously opened browser and then start a new instance and leave it on. As a result, only one instance of browser should be open at a time. I am using Mac.
public static void main(String[] args){
String website = "http://www.google.com";
System.setProperty(".....");
WebDriver driver = new ChromeDriver();
driver.get(website);
}
The behaviour atm is that everytime I execute this, chrome instance will just pile up. What is the best way to avoid this? I am not doing this for testing purpose. I'm doing this because I want to automate a task. Thanks.

You can try out this code :
public static void main(String[] args) {
System.setProperty("webdriver.chrome.driver", "D:\\Automation\\chromedriver.exe");
WebDriver driver = new ChromeDriver();
driver.get("https://www.google.com/");
try{
Runtime.getRuntime().exec("TASKKILL /F /IM chrome.exe");
}
catch(IOException io){
System.out.println(io.getMessage());
}
}
Note : It will kill all instances of chrome that was previously opened along with the newly opened instance.

If I understand correctly, you are trying to automate a part of the flow, then let the automation program exit leaving the browser open for completing rest of the steps manually. In this case, the best way to ensure only one such window is open would be to keep the automation script idling until you are done with with manual task. Something like this at end of your main function:
try {
while(true) {
Thread.sleep(1000);
driver.getCurrentUrl();
}
} catch(Exception e) {}
Would ensure that the program remains alive as long as the browser window is open. You can continue manual process in the browser. Once you are done, you can close the browser, which would automatically end this process. Or before starting the new task, you kill the old one with ^c, which in turn closes the browser.
The second option without keeping the automation script idling, would be to find the process id of newly created browser instance. You can save the process id in some file in temporary folder. Every time your script starts, it'd check the the file, read pid from it, and if the process id exists, try to kill it before spawning a new browser window.

Launch Opera and Wait Until it is Closed [duplicate]

Question
I want to start the Firefox web browser as process to visit a specific website, then wait until it is closed.
A special situation is that the browser may already be open and running, as the user may have visited some website already.
In that case, the browser would probably open a new tab in an existing window and the newly launched process will be terminated immediately. This should not confuse my waiting process: Either, I want a new browser window (if that can somehow be enforced, maybe via command line arguments) and wait until that is closed, or keep the existing browser window and wait until all the tabs resulting from my process are closed.
Environment
I think it doesn't matter, but my programming environment is Java and you can assume that I know the path of the browser.
Example
The only browser for which I can obtain the expected behavior is Internet Explorer (sigh.). Here, I need to basically create a new batch script in a temp folder with something like
start /WAIT "" "C:\Program Files\Internet Explorer\iexplore.exe" -noframemerging http://www.test.com/
I then run the batch script instead of directly the browser and delete it once I am finished with waiting.
Intended Process
To make the intended process clearer:
My program starts.
My program launches the Firefox browser as separate process and provides an URL to visit as argument to that process.
The Firefox browser runs asynchronously, as a new process, and visits the provided URL. So far, this is easy.
After launching the new process (the Firefox browser), my own program should wait for the said process to terminate. This is the hard part, as
Many modern browsers start multiple processes. I would need to wait for all of them.
Many modern browsers may somehow "detach" themselves from the process that I launched. Sorry, I don't know a better word, what I mean is: I start a process which then starts another process and terminates immediately while the other process keeps running. If I wait for the browser process originally started by my program, the waiting will be finished while the browser is still open.
A special case of the above is tabbed browsing as realized in many browsers: If the browser is already open (in a separate process started by the user) when I launch it, my newly started browser process may simple communicate the URL to visit to the existing process and terminate. The user is still on my provided URL while my program thinks she has closed the browser. This issue can maybe be forbidden by specifying a special command line argument, like noframemerging for the IE.
Once the browser has terminated or all tabs related to the URL I provide have been closed, my program will cease to wait and instead continue doing its business.
The use case is that I have a web application which can either run locally or on a server. If it is run locally, it launches a web server, then opens the browser to visit the entry page. Once the browser is closed, that web application should shut down as well. This works reliable for Internet Explorer, for all other cases, the user has to close the browser and then, explicitly, the web application. Thus, if I could wait reliably for Firefox to finish, this would make the user experience much better.
Solution Preferences:
Solutions are prefered in the following order
Anything which ships with the pure Java JRE. This includes special command line arguments to the browser.
Things that require me to, e.g., create a batch script (such as in the IE case.)
Anything that requires 3rd party open source libraries.
Anything that requires 3rth party closed source libraries.
Any platform independent answer (working both Windows and Linux) is prefered over platform-dependent ones.
Reason: In the ideal case, I would like to know what exactly is done and include it into my own code. As I want to support different browsers (see "PS" below), I would like to avoid having to include one library per browser. Finally, I cannot use commercial or closed source libraries, but if no better answer turns up, of course, I will honor any working solution with an accept. I will accept the first (reasonably nice) working answer of type "1". If answers of lower preference turn up, I will wait a few days before accepting the best one among them.
PS
I will launch a couple of similar questions for other browsers. Since I believe that browsers are quite different in the command line arguments they digest, the way the launch threads and sub-processes, I think this makes sense.
Similar question regarding Chrome: Launch Chrome and Wait Until it is Closed
Similar question regarding Opera: Launch Opera and Wait Until it is Closed
Similar question regarding Chromium: Launch Chromium and Wait Until it is Closed
Similar question regarding Edge: Launch Edge Browser and Wait Until it is Closed
Similar question regarding Safari: Launch Safari and Wait Until it is Closed

Here is a sample program that may somehow manages to demonstrate the capability of a selenium library to fulfill what you want. You need to download the selenium library and set it to your IDE first before you can run this program.
The program allows you to click a button. Then the firefox browser automatically opens and launch a website in a few seconds. Please wait while the website is loading. After that you may close the Firefox browser. The program shall also automatically close after 2 seconds.
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.net.ConnectException;
import javax.swing.*;
import org.openqa.selenium.NoSuchWindowException;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
public class AnotherTest extends JFrame {
WebDriver driver;
JLabel label;
public AnotherTest() {
super("Test");
java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
setBounds((screenSize.width - 400) / 2, (screenSize.height - 100) / 2, 400, 100);
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
setLayout(new BorderLayout());
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowClosing(java.awt.event.WindowEvent evt) {
quitApplication();
}
});
JButton jButton1 = new javax.swing.JButton();
label = new JLabel("");
JPanel panel = new JPanel(new FlowLayout());
panel.add(jButton1);
add(panel, BorderLayout.CENTER);
add(label, BorderLayout.SOUTH);
jButton1.setText("Open Microsoft");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
label.setText("Loading browser. Please wait..");
java.util.Timer t = new java.util.Timer();
t.schedule(new java.util.TimerTask() {
#Override
public void run() {
openBrowserAndWait();
}
}, 10);
}
});
}
private void openBrowserAndWait() {
driver = new FirefoxDriver();
String baseUrl = "https://www.microsoft.com";
driver.get(baseUrl);
java.util.Timer monitorTimer = new java.util.Timer();
monitorTimer.schedule(new java.util.TimerTask() {
#Override
public void run() {
while (true) {
checkDriver();
try {
Thread.sleep(2000);
} catch (InterruptedException ex) {
}
}
}
}, 10);
}
private void checkDriver() {
if (driver == null) {
return;
}
boolean shouldExit = false;
try {
label.setText(driver.getTitle());
} catch (NoSuchWindowException e) {
System.out.println("Browser has been closed. Exiting Program");
shouldExit = true;
} catch (Exception e) {
System.out.println("Browser has been closed. Exiting Program");
shouldExit = true;
}
if (shouldExit) {
this.quitApplication();
}
}
private void quitApplication() {
// attempt to close gracefully
if (driver != null) {
try {
driver.quit();
} catch (Exception e) {
}
}
System.exit(0);
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new AnotherTest().setVisible(true);
}
});
}
}
Selenium is primarily used for testing automation of web applications. It can directly open browsers and read the html contents in it. See http://www.seleniumhq.org/ for additional information.

comunication between Web browser and java

I Am developing a private web site in PHP-html / Ajax and a client program in Java.
I have just seen that apple can, by Firefox or other, open iTunes to load content.
I want to do the same or better:
I try to make a program which can “talk” to javascript or just write a lockFile (tempfile) and so get data through this one, i try to get at least a communication Web browser - > java, but i'd rather if possible a bi-directional communication.
So if somebody have any solution, it’s will be great cause I googlised it, i tried local Storage in html5, File access in javascript … nothing really works and I don’t want the program to ask the server Avery time.

You can do this in a number of ways but you must have in mind the cross-domain restrictions. I've been doing this with sockets.
1 - You need a bridge to comunicate your web with your server this could be done with a java applet or a flash socket bridge so that you can call your server and your javascript client code.
2 - You need url-redirect rule in your server so that when your client makes a request it always makes it in the same domain but gets where your socket server finally is. You client can't go to a different domain but your server can. This is needed to skip the cross-domain restriction.
I hope this helps.

You can take a look at JxBrowser library that allows embedding Google Chromium engine into Java Swing applications. You can use this library to embed Browser component into your client Java application and load your PHP web page, like iTunes loads App Store.
It provides API for two-way communication Java-to-JavaScript-to-Java: http://www.teamdev.com/downloads/jxbrowser/docs/JxBrowser-PGuide.html#javascript-java-bridge
The following code demonstrates how to embed Browser component, load URL, invoke JavaScript code on the loaded web page and register Java function on JavaScript side that will be invoked every time when JavaScript invokes it:
import com.teamdev.jxbrowser.chromium.Browser;
import com.teamdev.jxbrowser.chromium.BrowserFactory;
import com.teamdev.jxbrowser.chromium.BrowserFunction;
import com.teamdev.jxbrowser.chromium.JSValue;
import com.teamdev.jxbrowser.chromium.events.FinishLoadingEvent;
import com.teamdev.jxbrowser.chromium.events.LoadAdapter;
/**
* The sample demonstrates how to register a new JavaScript function and
* map it to a Java method that will be invoked every time when the JavaScript
* function is invoked.
*/
public class JavaScriptJavaSample {
public static void main(String[] args) {
Browser browser = BrowserFactory.create();
// Register "MyFunction" JavaScript function and associate Java callback with it
browser.registerFunction("MyFunction", new BrowserFunction() {
public JSValue invoke(JSValue... args) {
for (JSValue arg : args) {
System.out.println("arg = " + arg);
}
return JSValue.create("Hello!");
}
});
// Create JFrame and embed Browser component to display web pages
JFrame frame = new JFrame();
frame.add(browser.getView().getComponent(), BorderLayout.CENTER);
frame.setSize(800, 600);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
// Register Load listener to get notification when web page is loaded completely
browser.addLoadListener(new LoadAdapter() {
#Override
public void onFinishLoadingFrame(FinishLoadingEvent event) {
if (event.isMainFrame()) {
Browser browser = event.getBrowser();
// Invoke our registered JavaScript function
JSValue returnValue = browser.executeJavaScriptAndReturnValue(
"MyFunction('Hello JxBrowser!', 1, 2, 3, true);");
System.out.println("return value = " + returnValue);
}
}
});
browser.loadURL("about:blank");
}
}

Java JButton and swing problem

I am doing a networking project. I compiled a code under Java Project console app and it works. But when I create a GUI and assign the code to run when a button is pressed, it hangs on clicking the button.
This is the source code:
#Action
public void EstablishConnection() {
serverAddress = jTextFieldServerAddress.getText();
serverPort = Integer.parseInt(jTextFieldPort.getText());
serverUName = jTextFieldUName.getText();
serverUPwd = jTextFieldUPwd.getText();
try {
client = new FTPClient();
client.connect(serverAddress, serverPort);
boolean login = client.login(serverUName, serverUPwd);
if(login) {
System.out.println("Successfully logged in\n");
}
else {
System.out.println("Unable to login\n");
}
}
catch(Exception ex) {
System.out.println("Exception Raised: " + ex);
}
}
The action is called when a button is pressed in the swing app. It is not working for me. But it is working very fast for a console app.

Anytime I see the word "hang" I assume you need to be using a separate Thread to execute the hanging code. See Concurrency in Swing for the solution.

I would suggest that you should run code that depends on external factors, like accessing a remote server etc., that could delay the response, in a thread of it's own.
Display a MessageDialog with an indeterminate progress bar:
connProgressBar.setIndeterminate(true);
You neither know whether your connection will terminate, nor if it will, so add a button that allows the user to kill the connection thread, whenever she feels like it.
Since you are probably connecting to an ftp server in order to upload and download files, after the connection has been established, use a determinate progressbar that shows the download percentage of the file or files progress, that runs in a new thread.