The HTML/Java API provides {@link net.java.html.js basic building blocks} as well as advanced {@link net.java.html.json.Model high level concepts} to make communication between JavaScript and Java as smooth as possible.
Every browser widget Java API offers ways for communication between Java and JavaScript running in such widget. However, each of them is unique - e.g. one writes different code when communicating with {@link javafx.scene.web.WebView JavaFX WebView}, different one when communicating with Android WebView yet another one when talking to iOS WebView.
The goal of HTML/Java API is to unify this communication. By providing simple and highly portable {@link net.java.html.js basic building blocks} one can create sophisticated APIs (like {@link net.java.html.json UI bindings}, charts, maps, canvas, or SnapSVG that can be embedded into {@link net.java.html.boot.fx.FXBrowsers Swing or JavaFX applications}, executed {@link net.java.html.boot.script.Scripts headlessly on a server} or executed anywhere HTML/Java API was ported.
Various ports of this rendering pipeline were built including support for pure "webkit desktop rendring Android WebView and iOS WebView developed by DukeScript project.
This technology has also been adopted by some Java bytecode to JavaScript transpilers - for example TeaVM or Bck2Brwsr VM - as such you can also run the same Java application in a pluginless browser.
Porting of HTML/Java rendering pipeline is as easy as implementing {@link org.netbeans.html.boot.spi.Fn.Presenter} interface and successfully passing the {@link org.netbeans.html.json.tck test compatibility kit}.
Get the best of both worlds by combining the industry stability of Java and richness of JavaScript ecosystem when it comes to UI and rendering frameworks.
The HTML/Java API offers you unified access to full featured Java runtime (like real HotSpot VM) and very lightweight rendering technology (so it can potentially fit Bck2Brwsr and definitely to various types of phones - e.g. Android and iOS). What can be more lightweight (from a browser perspective) than HTML!? Speed up your development with {@link net.java.html.boot.fx JavaFX's WebView} component to display the HTML, get browser inspect features, CSS navigation and IDE integration.
The project has been donated to Apache Foundation and the code is now hosted in the incubator repository along other Apache incubating projects. Contribute to the project by forking its GitHub repository.
Using Android JSON parsing library as it is Apache licensed - bug #89. It is acceptable to read properties of a model when {@link net.java.html.json.ComputedProperty computing a property}. Regular subclassing of {@link org.netbeans.html.json.spi.Proto.Type} is possible. Bugfix #99 - better garbage collector related behavior of ko4j instances thanks to introduction of {@link org.netbeans.html.json.spi.Technology.ToJavaScript}. Mentioning knockout.js license in the ko4j artifact - bug #98. Simplifying dependencies of {@link org.netbeans.html.json.tck} - bug #111
Bug fix for multiple observers on a single model object. Better GC behavior specified in TCK and used in Knockout for Java implementation. Removing dependency on Java collection classes implementations. Adding {@link net.java.html.json.Models#asList} factory method to a create simple list implementation. Simplifying {@link org.netbeans.html.json.tck.KnockoutTCK} to avoid usage of {@link java.net.URI}, etc.
null
and undefined
are
treated as null.
Better behavior under
multi-threaded load.
Workaround for garbage collector behavior of modern JavaFX WebView
implementations (JDK8 u112 and newer).
JavaFX Presenter can
show popup window.
Development has switched to
Git repository thanks to
conversion by Emilian Bold.
Better support for obfuscation of knockout module
(bug
270013).
false
to define a non-mutable (almost constant) property. That
in case of Knockout bindings means: the property is
represented by a plain value rather than an observable in the JavaScript
object. The JavaFX presenter can be executed in headless mode -
just specify -Dfxpresenter.headless=true
when launching
its virtual machine and no window will be shown. This is particularly
useful for testing. Configure your surefire or failsafe
plugins like: <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>2.13</version> <configuration> <systemPropertyVariables> <fxpresenter.headless>true</fxpresenter.headless> </systemPropertyVariables> </configuration> </plugin>OSGi headers are now enterprise OSGi ready. Switched to minified version 3.4.0 of knockout.js. Better support for recursive @Model definitions. New module
org.netbeans.html:xhr4j
provides implementation
of {@link org.netbeans.html.json.spi.Transfer} with
{@link org.netbeans.html.context.spi.Contexts.Id technology identifier}
xhr4j - this module can be used to
workaround limitations
of CORS by handling the {@link net.java.html.json.OnReceive}
connections in Java.
Click the link to view even more historic changes...
One can control {@link net.java.html.json.OnReceive#headers() HTTP request headers}
when connecting to server using the {@link net.java.html.json.OnReceive}
annotation. It is possible to have
{@link net.java.html.json.ComputedProperty#write() writable computed properties}.
There is an easy way to enable Firebug in
the JavaFX based Web View -
just run with -Dfirebug.lite=true
as
this video
demonstrates.
Bugfix of issues 250503,
252987.
The content of a {@link net.java.html.BrwsrCtx context}
can be selected by registering implementations under specific
{@link org.netbeans.html.context.spi.Contexts.Id technology identifiers}
and requesting them during
{@link org.netbeans.html.context.spi.Contexts#newBuilder(java.lang.Object...) construction}
of the context. org.netbeans.html:ko4j
module's implementation
offers ko4j, xhr and websocket identifiers
for its registered services
(e.g. {@link org.netbeans.html.json.spi.Technology},
{@link org.netbeans.html.json.spi.Transfer} and
{@link org.netbeans.html.json.spi.WSTransfer}).
org.netbeans.html:ko-ws-tyrus
module registers its
{@link org.netbeans.html.json.spi.Transfer Java based JSON} and
{@link org.netbeans.html.json.spi.WSTransfer WebSocket} implementations
under the name tyrus.
A particular DOM subtree
that a knockout.js model gets
applied to can be selected by using
{@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String)
Models.applyBindings(m, id)} with an id of an HTML element.
There is new {@link net.java.html.json.Model#targetId()} attribute
which controls behavior of the generated applyBindings
method.
If specified and non-empty, then the generated method
will call {@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String)}
with this
and the provided {@link net.java.html.json.Model#targetId() target id}.
If specified, but left empty, then the generated method
calls {@link net.java.html.json.Models#applyBindings(java.lang.Object)}.
If unspecified, the method will not be generated at all
(a change with respect to older versions). However one can
still use {@link net.java.html.json.Models#applyBindings(java.lang.Object)}
or {@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String)}
to perform the association of any model with the page element.
Memory model when using Knockout bindings has been improved (required additions of two new methods: {@link org.netbeans.html.json.spi.PropertyBinding#weak()} and {@link org.netbeans.html.json.spi.FunctionBinding#weak()}) and now the Java {@link net.java.html.json.Model models} can garbage collect, when no longer used. Library writers that use {@link net.java.html.js.JavaScriptBody} annotation can also control garbage collection behavior of method arguments by setting {@link net.java.html.js.JavaScriptBody#keepAlive() keepAlive=false} attribute.
{@link net.java.html.json.Property#array() Array properties} are now mutable from the knockout.js point of view (required {@link org.netbeans.html.json.spi.Proto.Type#replaceValue one SPI change}). The page lookup mechanism can use {@link net.java.html.boot.BrowserBuilder#locale(java.util.Locale) locale} to load localized a page with appropriate suffix. All SPI were moved under the NetBeans namespace - e.g. {@link org.netbeans.html.boot.spi}, {@link org.netbeans.html.context.spi}, {@link org.netbeans.html.json.spi}, {@link org.netbeans.html.sound.spi}, and also {@link org.netbeans.html.json.tck}. Methods annotated with {@link net.java.html.js.JavaScriptBody} annotation and without fallback Java code now throw {@link java.lang.IllegalStateException} with a message suggesting to switch to proper {@link net.java.html.BrwsrCtx#execute browser context} to prevent endless debugging when one forgets to do so.
System can run in {@link net.java.html.boot.BrowserBuilder#classloader(java.lang.ClassLoader) Felix OSGi container} (originally only Equinox). {@link net.java.html.json.ComputedProperty Derived properties} now deeply check changes in other {@link net.java.html.json.Model model classes} they depend on and recompute their values accordingly. Knockout.js library has been updated to version 3.2.0.
Setters or array properties on classes generated by {@link net.java.html.json.Model}
annotation can be accessed from any thread. {@link org.netbeans.html.sound.spi.AudioEnvironment}
can be registered into {@link net.java.html.BrwsrCtx}. There is
a {@link net.java.html.json.Models#parse(net.java.html.BrwsrCtx, java.lang.Class, java.io.InputStream, java.util.Collection) method}
to parse a JSON array and convert it into
{@link net.java.html.json.Model model classes}.
Improved behavior of enum
values in
{@link net.java.html.json.Model knockout bindings}.
Few bugfixes for better portability. New API for {@link net.java.html.boot.script.Scripts headless execution} on top of Nashorn - does not run knockout for Java fully yet (reported as JDK-8046013), however even in current state it is quite {@link net.java.html.boot.script.Scripts useful for testing} of {@link net.java.html.js Java/JavaScript interactions}.
{@link net.java.html.boot.fx.FXBrowsers} has been extended with new helper methods to make it easier to use HTML+Java API in existing JavaFX applications. The annotation processor is made more robust with respect to errors in callback syntax of {@link net.java.html.js.JavaScriptBody} body parameter. Javadoc of {@link net.java.html.BrwsrCtx#execute} method has been improved based on a failure of its usability study. There can be additional parameters to methods annotated by {@link net.java.html.json.OnReceive} that allows one to pass state when a JSON call is made and use it when it finishes. The mechanism of discovery of sibling HTML page has been extended to work on systems that don't support {@link java.lang.Class#getProtectionDomain}.
The first argument of method annotated by {@link net.java.html.json.OnReceive} annotation has to be the associated {@link net.java.html.json.Model model class}.
{@link net.java.html.json.OnReceive} annotation now accepts {@link java.util.List} of data values as second argument (previously required an array).
{@link net.java.html.js.JavaScriptBody} annotation has new attribute {@link net.java.html.js.JavaScriptBody#wait4js()} which allows asynchronous execution. Libraries using {@link net.java.html.js.JavaScriptBody} are urged to use this new attribute as much as possible, as it can speed up execution in certain environments.
Use {@link net.java.html.BrwsrCtx#execute(java.lang.Runnable)} in multi-threaded environment to execute your code on the browser thread. See example {@link net.java.html.BrwsrCtx#execute(java.lang.Runnable) using Java timer}.
Learn how to {@link net.java.html.json.Model animate an HTML page from Java} without referencing single HTML element from the Java code.
Use {@link net.java.html.json.OnReceive JSON} to communicate with REST based server API.
Use WebSockets and JSON.
Call JavaScript methods from Java and vice versa, via JavaScriptBody.
$ mvn archetype:generate \ -DarchetypeGroupId=com.dukescript.archetype \ -DarchetypeArtifactId=knockout4j-archetype \ -DarchetypeVersion=0.16 # or newer version, if availableAnswer few questions (for example choose myfirstbrwsrpage as artifactId) and then you can:
$ cd myfirstbrwsrpage $ mvn install $ mvn -f client/pom.xml process-classes exec:execIn a few seconds (or minutes if Maven decides to download the whole Internet of dependencies) you should see a sample Hello World application. Immediatelly you can be productive without any redeploys - even more productive than with plain JavaScript!
The application is rendered in a
JavaFX
web view component (that of course requires your JDK to come
with JavaFX;
JDK7
and JDK8 from Oracle contain everything that is needed).
The generated application is built around one
Java source (uses the {@link net.java.html.json.Model} annotation to
auto-generate another Data.java
class during compilation)
and one HTML file (uses the Knockout
syntax to data-bind
the HTML elements to the
generated Data
model):
$ ls client/src/main/java/**/DataModel.java $ ls client/src/main/webapp/pages/index.htmlThat is all you need to get started. Play with the sources, modify them and enjoy Html for Java!
This API is part of NetBeans.org project and as such it works naturally with the NetBeans IDE. On the other hand, the API is using nothing NetBeans specific, it builds on standard Java6 APIs and as such it shall work fine in any IDE.
A lot of work is done by annotation processors that generate various boiler plate code during compilation. This is a standard part of Java since JDK6, but for example Eclipse is known not to deal with processors well and developers using it need to be careful. IntelliJ users hasn't reported any issues and of course, NetBeans IDE support for processors is outstanding.
When using {@link net.java.html.js.JavaScriptBody} annotation, it is useful to do a bit of post processing of classes. There is a Maven plugin for that. NetBeans IDE will invoke it when doing a build. Other IDEs may need some hint to do so. Anyway: If one does not see all (generated) sources or is getting {@link java.lang.LinkageError}s when executing the application, switch to command line and do clean build from there:
$ mvn clean install
If that succeeds, your IDE of choice will hopefully pick the generated sources up and present the result of the build properly. If not, download NetBeans, you will be pleasantly surprised - for example with our excellent Java/JavaScript debugging support.
It is not goal of this documentation to list all possible ways to package and deploy applications which use this API. However it is important for new comers to see the benefits of using the HTML for Java API and as such let's list at least few bundling options, known to work at the time of writing this documentation.
First of all, this is a client technology. You write client applications with it which may, but need not connect to a server. You don't need Tomcat or WebLogic to deploy HTML for Java applications.
The sample project generated by
org.apidesign.html knockout4j-archetype
is configured
to use JavaFX
as the rendering technology. This setup is primarily suitable for
development - it needs no special packaging, starts quickly and
allows you to use classical HotSpot VM debuggers. A final
artifact from the build is also a ZIP file which you can use
and distribute to your users. Good for desktop applications.
All the HTML for Java libraries
are packaged as OSGi
bundles and as such they can easily be run in NetBeans as well as
in Eclipse. As a result one can use
OSGi
and have a common module system for both platforms. In addition to that
one can render using
HTML and have a common UI in both platforms. In such case
your application would be packaged as a set of
OSGi bundles.
Read
more...
There is more and more attempts to execute Java bytecode
in a browser, without any special Java plugin installed.
The HTML for Java is
carefully designed to produce lightweight, well performing
applications even on such restricted environments. It uses
no reflection calls and that allows to statically pre-compile
the applications into JavaScript. One of such environments
is called Bck2Brwsr,
another TeaVM. Both support the
{@link net.java.html.js.JavaScriptBody} annotation. Read
more or play
a minesweeper game packaged for your browser
(of course written in Java):
Now when we have seen that the
HTML for Java applications
can run on any modern browser, we can ask whether they can also
fit into a phone!? Yes, they can and especially to phones
that can execute Java code already! Just by changing your
packaging you can create an APK file and deploy it to your
Android phone.
Read more
or install
Fair Minesweeper for Android...
In case you'd like your application to reach out to second biggest group of smartphone users, don't despair: It seems the set of devices that can execute HTML for Java applications has been extended to iPads and iPhones. Get the details here and play Fair Minesweeper on iOS!
Convinced it makes sense to use HTML for Java APIs for writing applications that are written once, displayed anywhere? Or do you have an environment which is not supported? In such case you can bring HTML for Java to your environment yourself. Just implement your own {@link org.netbeans.html.boot.spi.Fn.Presenter}!