如何用Java代码生成EMF模型

Question

我想用Java代码生成EMF模型。例如，我想创建一个新的Ecore建模项目，然后构建一个简单的模型，就像很多教程（比如vogella教程）中看到的那样。但我不想用GUI手工完成。我想学习如何使用EMF-Ecore-API用Java代码创建模型。

我试着找关于这个话题的教程。但令我失望的是，我找不到太多关于这个话题的资料。我能找到的唯一东西是一些代码片段，用来按代码加载和修改现有模型。但没有关于创建新模型的内容。只是翻阅API对我没有帮助。

有关于这个话题的消息来源吗？如果不是，我如何通过java代码创建EMF模型？

Answer 1

IBM有一个关于动态EMF的主题。

但如果您熟悉EMF中的创建工作方式，那么这是非常简单的。每个EPackage都有自己的eFactory和EPackage实例，它们处理创建（工厂）或存储有关元模型本身的信息（EPackage）。

Ecore有自己的ePackage和eFactory，因此完全可以像这样动态创建新的元模型：

    /*Use the Ecore factory*/
    EcoreFactory ecoreFactory = EcoreFactory.eINSTANCE;
    /*Create your EPackage*/
    EPackage myPackage = ecoreFactory.createEPackage();
    /*set EPackage properties*/
    myPackage.setName("myTest");
    myPackage.setNsPrefix("myTest");
    myPackage.setNsURI("http://com.myTest");

    /*Create your first EClass*/
    EClass myFirstEClass = ecoreFactory.createEClass();
    myFirstEClass.setName("myClass");
    /*Add to your EPackage's EClassifiers*/
    /*EClasses and EDatatypes implement both EClassifiers*/
    myPackage.getEClassifiers().add(myFirstEClass);

    /*Create your first EAtttribute*/
    EAttribute myFirstEAtt = ecoreFactory.createEAttribute();
    myFirstEAtt.setName("name");
    /*Use the EcorePackage Datatypes -> here EString*/
    myFirstEAtt.setEType(EcorePackage.eINSTANCE.getEString());
    /*use EStructuralFeatures to add your EAtt*/
    /*EReferences and EAttributes are both EStructuralfeatures*/
    myFirstEClass.getEStructuralFeatures().add(myFirstEAtt);

    /*Create your second EClass*/
    EClass mySecondEClass = ecoreFactory.createEClass();
    mySecondEClass.setName("mySecondClass");
    myPackage.getEClassifiers().add(mySecondEClass);

    /*now, the firstClass should hold instances of secondClass*/
    /*1. create EReference (Ereferences unlike EAttributes define relationships between EClasses)*/
    EReference secondClassesRef = ecoreFactory.createEReference();
    secondClassesRef.setName("secondClasses");
    /*set containment true -> every EObject must have a Container*/
    secondClassesRef.setContainment(true);
    /*set Type to your EClass*/
    secondClassesRef.setEType(mySecondEClass);
    /*set upperbound -> now the reference is an EList*/
    secondClassesRef.setUpperBound(ETypedElement.UNBOUNDED_MULTIPLICITY);

    /*finally add ERef to EClass*/
    myFirstEClass.getEStructuralFeatures().add(secondClassesRef);

    /*and for example supertypes*/
    myFirstEClass.getESuperTypes().add(mySecondEClass);

现在您有了自己的ePackage和新的eClass,它的eAttribute名称类型为eString

现在，还可以将新的EPackage保存到.ecore文件中，如下所示：

    /*
     * Save your EPackage to file ecore file:
     */

    /*Initialize your EPackage*/
    myPackage.eClass();
    Resource.Factory.Registry reg = Resource.Factory.Registry.INSTANCE;
    Map<String, Object> m = reg.getExtensionToFactoryMap();
    /*add default .ecore extension for ecore file*/
    m.put(EcorePackage.eNAME, new XMIResourceFactoryImpl());

    // Obtain a new resource set
    ResourceSet resSet = new ResourceSetImpl();
    // create a resource
    Resource resource = null;
    try {
        resource = resSet.createResource(URI.createFileURI("/Your/Path/To/Directory/myTest.ecore"));
    } catch (Exception e) {
        e.printStackTrace();
    }
    /*add your EPackage as root, everything is hierarchical included in this first node*/
    resource.getContents().add(myPackage);

    // now save the content.
    try {
        resource.save(Collections.EMPTY_MAP);
    } catch (IOException e) {
        e.printStackTrace();
    }

如果要加载现有的ecore ePackage,反之亦然：

    /*
     * load existing EPackage
     */
    EcorePackage.eINSTANCE.eClass();
    /*Initialize your EPackage*/
    final Resource.Factory.Registry reg = Resource.Factory.Registry.INSTANCE;
    final Map<String, Object> m = reg.getExtensionToFactoryMap();
    m.put(EcorePackage.eNAME, new XMIResourceFactoryImpl());

    final ResourceSet resSet = new ResourceSetImpl();
    Resource resource = null;
    try {
        resource = resSet.getResource(URI.createFileURI("/Your/Path/To/Directory/myTest.ecore"), true);
    } catch (Exception e) {
        e.printStackTrace();
    }
    /*load root and cast to EPackage*/
    final EPackage root = (EPackage) resource.getContents().get(0);

我还更新了上面的代码，向您展示了如何初始化eclass之间的关系