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It's a set of helper processors that can speed up J2CL development by generating boiler-plate code.

The latest version:https://search.maven.org/search?q=g:org.treblereel.j2cl.processors

It contains the following features:

• @GWT3EntryPoint acts pretty much the same asGwt2 EntryPoint, the annotated method will be called on application startup.

  publicclassApp {@GWT3EntryPointpublicvoidinit() {HTMLButtonElementbtn = (HTMLButtonElement)DomGlobal.document.createElement("button");btn.textContent ="PRESS ME !";  }}

• @ES6Module allows us to use Es6 modules via JsInterop.

  @ES6Module@JsType(isNative =true,namespace ="org.treblereel.j2cl.shim")publicclassES6Test {publicStringid;publicnativebooleanisTest(); }

  classES6Test{constructor(){/**@type {string} */this.id="#id"}/**  *@return {boolean}  */isTest(){returntrue;}}export{ES6Test};

• @GWT3Export allows a resulted JavaScript file to be called from the pure JavaScript environment.

  publicclassExportTestClass {@GWT3ExportpublicstaticStringtest(Strings) {returns;    }@GWT3ExportpublicPromise<String>promise() {returnPromise.resolve("Hello world!");    }}

  vartest=neworg.treblereel.j2cl.exports.ExportTestClass();test.test('INSTANCE METHOD CALL');test.promise().then(function(result){});

• @TranslationBundle j2cl-maven-plugin 0.21 brings us support of Closure's.xtb translation bundles that are a very effective way to translate your application.

  • Note: at the moment,.xtb support is only available for j2cl-maven-plugin 0.21 and above and works only in ADVANCED mode, otherwise default values will be used.

  To use@TranslationBundle, you need to do the following steps:

1. In the configuration section of j2cl-maven-plugin, enable.xtb auto discovery:

  <translationsFile>    <auto>true</auto>  </translationsFile>

2. To a set locale for current compilation, you need to add the following line to yourpom.xml

  <defines>    <goog.LOCALE>en</goog.LOCALE>  </defines>

3. Create an interfaceMyBundle annotated with@TranslationBundle

@TranslationBundlepublicinterfaceMyBundle {    ...  }

The processor will generate theMyBundleImpl.java implementation in the same package whereMyBundle is.

4. Create a translation property bundle forMyBundle with a locale declared in the following format:

   • MyBundle_en.properties orMyBundle_en_US.properties containing key value pairs like:
   • hello = Hello World! orhello = Hello {$arg}!
     
     Note:{$arg} is a placeholder for a string argument.

5. Declare corresponding methods in yourMyBundle interface.

@TranslationBundlepublicinterfaceMyBundle {@TranslationKey(defaultValue ="Hello World!")Stringhello();@TranslationKey(defaultValue ="Hello {$arg}!")Stringhello(Stringarg);  }

Default value is used if no translation property value is found for a given locale and key.If a value contains the{$arg} placeholder, it will be replaced with the argument provided to the method. Placeholder is surrounded with curly brackets and a corresponding method argument must be named the same;

6. Values can be in HTML, in this case HTML will be escaped. To unescape it, setunescapeHtmlEntities = true in the@TranslationKey annotation.

@TranslationKey(defaultValue ="<div>HELLO</div>",unescapeHtmlEntities =true)Stringhello();

7. Each method should have a corresponding key value pair in a translation property file. Otherwise, a default value will be used. A method name can be overridden in@TranslationKey annotation.

@TranslationKey(key ="greetings",defaultValue ="Hello World!")Stringhello();

• @GWT3Resource is a lightweight port of GWT2 resources. Its main purpose is to embed various resources into the JavaScript bundle.

  Here we declared a bundle of the resources that will be embedded into the JavaScript bundle:

  @GWT3ResourcepublicinterfaceCombinedClientBundleextendsClientBundle {@Source("logo.png")ImageResourcelinuxLogo();TextResourcewelcome();@DataResource.MimeType("audio/mpeg")@Source("alarmloop.mp3")DataResourceresourceMimeTypeAnnotationAudioOgg();   }

  Later, we can use it like this:

  CombinedClientBundleresources =CombinedClientBundleImpl.INSTANCE;DomGlobal.document.body.appendChild(resources.linuxLogo().getImage());HTMLDivElementcontainer = (HTMLDivElement)DomGlobal.document.createElement("div");DomGlobal.document.body.appendChild(container);container.textContent =resources.welcome().getText();HTMLAudioElementaudio = (HTMLAudioElement)DomGlobal.document.createElement("audio");DomGlobal.document.body.appendChild(audio);audio.src =resources.resourceMimeTypeAnnotationAudioOgg().asString();audio.controls =true;

Take a look at tests for more details.