Javascript call Applet example

Calling java methods in javascript code

Java Code: Web page and Javascript code: Solution 2: Java is a server side language, whereas javascript is a client side language. Formerly Mozilla-specific LiveConnect functionality, such as the ability to call static Java methods, instantiate new Java objects and reference third-party packages from JavaScript, is now available in all browsers.

Calling java methods in javascript code

i created a java class content method return a String, my question is how to call this function in my javascript code to use the returned value from the java method. I want to call client-side Java code embedded in browser.

here is an exemple of what im talking about:

in my webpage i have a JavaScript code, here is some of it:

 function createChartControl(htmlDiv1) < // Initialize Gantt data structures //project 1 var parentTask1 = new GanttTaskInfo(1, "Old code review", new Date(2010, 5, 11), 208, 50, ""); . 

i want to create a java class content methods to provide data to this javascript function "GanttTaskInfo". for exemple function to get name, get id and date. well i think this time im clear 😀 i searched a way to call java methods in javascript, and i found applets as you said, but i think its not usefull to me. thanks again

When it is on server side, use web services - maybe RESTful with JSON.

• create a web service (for example with Tomcat)
• call its URL from JavaScript (for example with JQuery or dojo)

When Java code is in applet you can use JavaScript bridge. The bridge between the Java and JavaScript programming languages, known informally as LiveConnect, is implemented in Java plugin . Formerly Mozilla-specific LiveConnect functionality, such as the ability to call static Java methods, instantiate new Java objects and reference third-party packages from JavaScript, is now available in all browsers.

Below is example from documentation. Look at methodReturningString .

public class MethodInvocation extends Applet < public void noArgMethod() < . >public void someMethod(String arg) < . >public void someMethod(int arg) < . >public int methodReturningInt() < return 5; >public String methodReturningString() < return "Hello"; >public OtherClass methodReturningObject() < return new OtherClass(); >> public class OtherClass

Java is a server side language, whereas javascript is a client side language. Both cannot communicate. If you have setup some server side script using Java you could use AJAX on the client in order to send an asynchronous request to it and thus invoke any possible Java functions. For example if you use jQuery as js framework you may take a look at the $.ajax() method. Or if you wanted to do it using plain javascript, here's a tutorial.

Calling java method in javascript, javascript runs in your browser, your java code is deployed in your container (Tomcat). So only way to invoke this is via a Web call. Your javascript should invoke an ajax call to one servlet (configured in web.xml) and this servlet should invoke your java method. You can run javascript in server as well.See …

Is it posible to call java class from javascript?

I need to make some UI part in javascript for android application for that I'm writing some code in javascript and load it in android web view. Now, I want to call java class from javascript.

Is it possible to call java class from javascript?

It's possible, but I wouldn't do it for your given use case 🙂 (the UI could be done with the Android framework)

You can add what they call "Javascript Interfaces", which are basically links from Javascript to java code. First, define a class to bind containing the methods you which to call, and add it to your WebView :

 class HelloInterface < public void test(String name) < Log.i(TAG, "Hello " + name); >> webview.addJavascriptInterface(new HelloInterface(), "HELLO"); 

Then, from your javascript code, you can just call

Post #6 of-> http://ubuntuforums.org/showthread.php?t=565819

its actually reall easy (and cool) use:

webView.addJavascriptInterface(js, "pageObject"); 

js is a java object made in you activty (or somewhere where you init the webview), pageObject is the namespace identifier (variable) you can use with javaScript on your webpage.

How to call GWT java function from Javascript?, your example is not going to work, since you are trying to use JSNI in some external script. If you want to call something from external JS you need to use approach described in this question or use GWT exporter. UPDATE: The safest way to expose the GWT stuff is to wrap invocation in some other function.

Calling java method in javascript

I am trying to call a Java method in a javascript. java class resides in server side.

public class deleteconfig < static boolean check = true; public static void initiate() < check = false; >> 

I would like to call my deleteconfig.initiate() method in my javascript

Any help is greatly appreciated.

As javascript is a client side script, it cannot invoke java methods directly which resides on the server

Without any particular java frameworks, you could make use of Java Server Pages (JSP) to invoke deleteconfig.initiate() when it receives a GET request from javascript.

Sending Request

You might also want to use JQuery (a javscript plugin - http://jquery.com/) to send an asynchronous GET request to the server like this

//javascript code function callInititiate() < //This sends a get request to executeInit.jsp // $.get('localhost/myWebbApp/executeInit.jsp'); >$(callInitiate); 

Receive Request

On the server side, you should have executeInit.jsp that calls deleteconfig.initiate() static method

Perhaps reading more about Java Server Pages can get you started!

javascript runs in your browser, your java code is deployed in your container(Tomcat).

So only way to invoke this is via a Web call. Your javascript should invoke an ajax call to one servlet(configured in web.xml) and this servlet should invoke your java method.

You can run javascript in server as well.See NodeJS

You can use JavaServerPage (JSP) or Applets, here's an example for JSP for your situation:

• Expressions: The expression is evaluated and printed out the document.
• Scriptlet The code is inserted into the servlet service method.
• Statements: The code is inserted into the servlet class, outside of any method.

For JSP scripting elements is possible and another syntactic form, based on XML markup:

Your Javascript runs client side in the browser so will not normally interact with your Java code running server side. You might want to expose your Java method as a RESTful API endpoint and perform an AJAX call in the Javascript code.

There are a few ways it's technically possible but unsure why you would want to do it that way:

• SEE: http://www.andonyar.com/rec/2008-12/gemse/demo/doc/dev/java.xhtml
• SEE: http://www.rgagnon.com/javadetails/java-0170.html

Google's web toolkit: - SEE: http://code.google.com/p/google-web-toolkit-doc-1-5/wiki/DevGuideRPCDeployment

Call javascript from javascript Code Example, ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); // read script file engine.eval(Files

Call external javascript functions from java code

By using Java Scripting API, I am able to execute JavaScript within Java. However, can someone please explain what I would need to add to this code in order to be able to call on functions that are in C:/Scripts/Jsfunctions.js

import javax.script.*; public class InvokeScriptFunction < public static void main(String[] args) throws Exception < ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); // JavaScript code in a String String script1 = "function hello(name) "; String script2 = "function getValue(a,b) < if (a===\"Number\") return 1; else return b;>"; // evaluate script engine.eval(script1); engine.eval(script2); Invocable inv = (Invocable) engine; inv.invokeFunction("hello", "Scripting!!"); //This one works. > > 

Use ScriptEngine.eval(java.io.Reader) to read the script

ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); // read script file engine.eval(Files.newBufferedReader(Paths.get("C:/Scripts/Jsfunctions.js"), StandardCharsets.UTF_8)); Invocable inv = (Invocable) engine; // call function from script file inv.invokeFunction("yourFunction", "param"); 

Let us say your jsfunctions.js file has a function "display" and this file is stored in C:/Scripts/Jsfunctions.js

var display = function(name)

Now, in your java code, I would recommend you to use Java8 Nashorn. In your java class,

import java.io.FileNotFoundException; import java.io.FileReader; import javax.script.Invocable; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; class Test < public void runDisplay() < ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn"); try < engine.eval(new FileReader("C:/Scripts/Jsfunctions.js")); Invocable invocable = (Invocable) engine; Object result; result = invocable.invokeFunction("display", helloWorld); System.out.println(result); System.out.println(result.getClass()); >catch (FileNotFoundException | NoSuchMethodException | ScriptException e) < e.printStackTrace(); >> > 

Note: Get the absolute path of your javascript file and replace in FileReader() and run the java code. It should work.

How to make ajax call from JavaScript, Ajax is used to read data from the server and update the page or send data to the server without affecting the current client page. Ajax is a programming concept. Below are some ways to make Ajax call in JavaScript. Approach 1: In this approach, we will use the XMLHttpRequest object to make Ajax call. The …

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How to call Java applet's methods and variables from Javascript

Javascript can talk to Java applet in the same HTML page through LiveConnect technology. We can write Javascript code to invoke methods (including arguments) and access objects which are exposed by the applet. Here are the rules:

returnValue = AppletID.appletMethod(arg1, arg2, …)

returnValue = AppletID.publicVar

returnValue = AppletID.publicVar.publicMethod(arg1, arg2, …)

Where AppletID is the id attribute of the tag:

• • Javascript code can access only public methods and variables.
  • Both static or instance methods/variables can be accessed.

  1. Javascript call Java Applet Quick Example

  Following is a pretty simple example that demonstrates invoking a Java applet’s method from Javascript code. Here is code of the applet ( QuickApplet.java ):

  import java.awt.*; import javax.swing.*; public class QuickApplet extends JApplet < private JLabel label = new JLabel("This is a Java applet"); public void init() < setLayout(new FlowLayout()); label.setFont(new Font("Arial", Font.BOLD, 18)); label.setForeground(Color.RED); add(label); >public void drawText(String text) < label.setText(text); >>

  This applet shows only label and declare a public method drawText(String) which updates the label’s text.

  Here is code of the HTML page ( QuickAppletTest.html ):

  This HTML page embeds the above applet and displays a button which will invoke the applet’s method when clicked. The Javascript method callApplet() invokes the drawText() method of the applet and passes a time string as an argument. The applet, in turn, updates the label’s text by the string passed from Javascript code. Here is a screenshot of the page:

  

  2. Invoking Java applet’s methods

  • • Because variables in Javascript are untyped, so they will be converted to Java equivalents based on signature of Java methods.
    • Return values from Java methods are converted to closest Javascript equivalents (for primitive types) or Javascript wrapper object (for Object types).

    public int sum(int x, int y)

    var sum = sampleApplet.sum(10, 20);

    public String changeCase(String text)

    var returnText = sampleApplet.changeCase("code java");

    var returnText = sampleApplet.changeCase(123456);

    public boolean toggleVisible(boolean visible)

    var booleanReturn = sampleApplet.toggleVisible(true);

    var booleanReturn = sampleApplet.toggleVisible(""); // return true var booleanReturn = sampleApplet.toggleVisible("visible"); // return false

    public int sum(int[] numbers) < int sum = 0; for (int i = 0 ; i < numbers.length; i++) < sum += numbers[i]; >return sum; >

    var numbers = new Array(); numbers[0] = 10; numbers[1] = 20; numbers[2] = 30; var sum = sampleApplet.sum(numbers);

    3. Accessing Java applet’s variables

    Javascript code can access only public variables (both instance and static) declared in the applet. If the variable is of type Object, we can invoke methods on the returned object (and pass arguments) like the above section.

    Access primitive variables:Code in Java applet:

    var email = sampleApplet.email; email = email.substring(5, 18); email = "info@codejava.net"; email = email.toUpperCase();

    In this example, we obtain a String object from the applet and call String’s substring(int, int) and toUpperCase() methods. The similar can be applied for other Object types.

    Other Java Applet Tutorials:

    About the Author:

    

    Nam Ha Minh is certified Java programmer (SCJP and SCWCD). He started programming with Java in the time of Java 1.4 and has been falling in love with Java since then. Make friend with him on Facebook and watch his Java videos you YouTube.

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    Comments

    Hi,
    It's 2015 and I'm still trying to embed a java applet! There doesn't seem to be a lot of expertise out there these days (or nobody wants to admit to knowing).

    Everything seems to work, expect occasionally, under certain circumstance a call into the applet does not return in a timely fashion and causes the entire browser to hang. is there a way to get the call to throw an exception after some time if it does not a response?

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