SDO对EMF的依赖.doc

事实上，IBM 的 SDO 参考实现就是一种 SDO 的 EMF 实现。一、 SDO 创建对象的过程与Ecore创建对象的过程比较1、 SDO创建对象分两种情况：直接从XSD文件创建和用程序创建。 我们这里所说的直接从XSD文件创建是指：在创建对象暂时理解为由schema定义的一个有一定结构的xml文档之前它的模型（也就是相应的schema）就已经存在了，程序运行过程中只需要把这个模型加载便可。HelperContext scope=SDOUtil.createHelperContext();XSDHelper xsdHelper=scope.getXSDHelper();URL url=getClass().getResource(“/”+”company.xsd”);xsdHelper.define(url.OpenStream(),url.toString();如此静态模型加载完毕，之后要创建一个根对象。DataObject company=scope.getDataFactory().create(“Company.xsdThe url of the tyep”,”CompanyTypeThe name of the Type.”);其实这个时候我们创建的company对象就是之前我们所提到的根对象（RootObject），接下来的工作就是按照schema模型的定义，一层一层对company进行填充。用程序创建指：在创建对象之前不存在它的定义，我们需要在程序运行过程当中定义，这个过程可能比较麻烦。其实就是用程序来生成一个schema.看下面这段实例代码：Type intType = typeHelper.getType(commonj.sdo, Int); Type stringType = typeHelper.getType(commonj.sdo, String); DataObject customerType = scope.getDataFactory().create(commonj.sdo, Type); customerType.set(uri, /customer); customerType.set(name, Customer); 创建一个类型 DataObject custNumProperty = customerType.createDataObject(property); custNumProperty.set(name, custNum); custNumProperty.set(type, intType);创建一个属性对象，并且设置它的名称和类型 DataObject lastNameProperty = customerType.createDataObject(property); lastNameProperty.set(name, lastName); lastNameProperty.set(type, stringType); DataObject firstNameProperty = customerType.createDataObject(property); firstNameProperty.set(name, firstName); firstNameProperty.set(type, stringType); Type t = typeHelper.define(customerType); Type testType = scope.getTypeHelper().getType(/customer, Customer); DataFactory factory = scope.getDataFactory(); DataObject customer1 = factory.create(/customer, Customer); customer1.setInt(custNum, 1); customer1.set(firstName, John); customer1.set(lastName, Adams);按照上面创建的schema创建一个customer对象 2、 Ecore创建对象过程EcoreFactory ecoreFactory = EcoreFactory.eINSTANCE;EcorePackage ecorePackage = EcorePackage.eINSTANCE;/创建一Company类EClass companyClass = ecoreFactory.createEClass();companyClass.setName(Company);/创建公司名 EAttribute companyName = ecoreFactory.createEAttribute();companyName.setName(name);companyName.setEType(ecorePackage.getEString();companyClass.getEStructuralFeatures().add(companyName);/创建一Employee类EClass employeeClass = ecoreFactory.createEClass();employeeClass.setName(Employee);/在Employee类上添加一个名字属性EAttribute employeeName = ecoreFactory.createEAttribute();employeeName.setName(name);employeeName.setEType(ecorePackage.getEString();employeeClass.getEStructuralFeatures().add(employeeName);/创建一Department类EClass departmentClass = ecoreFactory.createEClass();departmentClass.setName(Department);/添加department标志数字EAttribute departmentNumber = ecoreFactory.createEAttribute();departmentNumber.setName(number);departmentNumber.setEType(ecorePackage.getEInt();departmentClass.getEStructuralFeatures().add(departmentNumber);/department类能够包含到一个或多个employee的参考EReference departmentEmployees = ecoreFactory.createEReference();departmentEmployees.setName(employees);departmentEmployees.setEType(employeeClass);/指定它可能是一个或多个employeedepartmentEmployees.setUpperBound(ETypedElement.UNBOUNDED_MULTIPLICITY);departmentEmployees.setContainment(true);departmentClass.getEStructuralFeatures().add(departmentEmployees);/company能够包含到一个或多个departments的参考EReference companyDepartments = ecoreFactory.createEReference();companyDepartments.setName(department);companyDepartments.setEType(departmentClass);companyDepartments.setUpperBound(ETypedElement.UNBOUNDED_MULTIPLICITY);companyDepartments.setContainment(true);companyClass.getEStructuralFeatures().add(companyDepartments);/创建一个包-描述companyEPackage companyPackage = ecoreFactory.createEPackage();companyPackage.setName(company);companyPackage.setNsPrefix(company);companyPackage.setNsURI(pany.ecore);companyPackage.getEClassifiers().add(employeeClass);companyPackage.getEClassifiers().add(departmentClass);companyPackage.getEClassifiers().add(companyClass);通过使用反射API，你能创建并且初始化一个你的模型的实例：/得到company工厂EFactory companyFactory = companyPackage.getEFactoryInstance();/使用工厂来创建company类的实例并且/设置company名字EObject company = companyFactory.create(companyClass);company.eSet(companyName, MyCompany);/创建一个employee类的实例 EObject employee = companyFactory.create(employeeClass);/使用反射API初始化employee的名字employee.eSet(employeeName, John);/创建一个department类的实例EObject department = companyFactory.create(departmentClass);department.eSet(departmentNumber, new Integer(123);/添加John到department(List)department.eGet(departmentEmployees).add(employee);/添加department到company(List)company.eGet(companyDepartments).add(department);通过上面两个例子，可以很清楚的看到对的依赖，他们创建模型的过程非常相似。二、 （反）串行化因为EMF能够处理多重模型源,包括XML模式,通常,当你调用ResourceSet.createResource(URI)方法时,它查询Resource.Factory.Registry来查找一个工厂-该工厂是为该URI而注册的并且使用它来创建一个适当的资源实现。因此,在你(反)串行化你的数据以前，请确保你已注册了适当的资源工厂实现。EMF提供若干Resource.Factory实现:对于XMI数据，使用org.eclipse.emf.ecore.xmi.impl.XMIResourceFactoryImpl。对于Ecore模型，使用org.eclipse.emf.ecore.xmi.impl.EcoreResourceFactoryImpl。你的工具箱中有了这些EMF资源后，你就能使用下面的代码来串行化你的数据:/创建资源集和资源ResourceSet resourceSet = new ResourceSetImpl();/注册XML资源工厂resourceSet.getResourceFactoryRegistry().getExtensionToFactoryMap().put(xmi, new XMIResourceFactoryImpl();Resource resource = resourceSet.createResource(URI.createFileURI(c:/temp/company.xmi);/添加根对象到资源resource.getContents().add(company);/串行化资源-你还能指定串行化/选项，它定义在org.eclipse.emf.ecore.xmi.XMIResource中resource.save(null);company.xmi被串行化后的形式如下：?xml version=1.0 encoding=ASCII?company:Company xmi:version=2.0 xmlns:xmi=/XMIxmlns:company=pany.ecore name=MyCompanydepartment number=123employees name=John/department/company:Company三、 EMF的反射机制和的反射机制1. EMF中的一个关键接口是Eobject，它在概念上等价于java.lang.Object。所有的建模对象，无论是