问题 单项选择题

为了使构件系统更切合实际、更有效地被复用,构件应当具备 (26) ,以提高其通用性。

A.可继承性

B.可变性

C.可封装性

D.可伸缩性

答案

参考答案:B

解析:

[分析]: 软件复用是使用已有的软件产品(如设计、代码、文档等)来开发新的软件系统的过程。软件复用的形式大体可分为垂直式复用和水平式复用。水平式复用是复用不同应用领域中的软件元素,例如数据结构、排序算法、人机界面构件等。标准函数库是一种典型的原始的水平式复用机制。垂直式复用是在一类具有较多公共性的应用领域之间复用软件构件。由于在两个截然不同的应用领域之间进行软件复用潜力不大,所以垂直式复用受到了广泛关注。
垂直式复用活动的主要关键点在于领域分析:根据应用领域的特征和相似性,预测软件构件的可复用性。一旦根据领域分析确认了软件构件的可复用价值,即可进行软件构件的开发,并对具有可复用价值的软件构件做一般化处理,使它们能够适应新的类似的应用领域。然后将软件构件和它们的文档存入可复用构件库,成为可供未来开发项目使用的可复用资源。
软件复用的范围不仅涉及源程序代码,Caper Jones定义了10种可能复用的软件要素,分别是项目计划、成本估计、体系结构、需求模型和规格说明、设计、源程序代码、用户文档和技术文档、用户界面、数据结构和测试用例。
可复用构件库的组织方式有枚举分类、关键词分类、多面分类、超文本组织法和可复用构件的3C模型。其中,3C指概念(concept)、内容(content)和语境(context)。
软件构件复用的步骤可分为检索与提取构件、理解与评价构件、修改构件和构件的合成。其中构件的合成又分为基于功能的合成技术和基于数据的合成技术。
目前流行的构件技术能有效地支持软件复用。为了提高构件的复用率,通常要求构件具有较好的通用性和可变性。通用性越好,其被复用的面越广。可变性越好,构件就越易于调整,以便适用于应用的具体环境。
为了将不同软件生产商在不同软硬件平台上开发的构件组装成一个应用系统,必须解决异构平台的各构件间的互操作问题。目前已出现了一些支持互操作的构件标准,分为OMG的CORBA、Microsoft的COM/DCOM和Sun的EJB/J2EE三个主要流派。

阅读理解

阅读理解。

     It's Monday today. Miss White comes into the classroom. She sees Mike, the tallest student, is

 standing in front of the blackboard and speaking like a teacher. The boy does not see her and is still

 standing there. The children begin to laugh and he looks round and finds Miss White is standing behind

  him, so he runs back to his row.

    "Morning, class," says Miss White. "Morning, Miss White." Ann stands up and says,

 "Sam and I are on duty today. Sixteen boys and eighteen girls are all here." Sixteen boys? Who doesn't

  come today?" asks Miss White. "Bill and his family move to London." "Oh, I see," Miss White says. But

 she sees a cat on the teacher's desk. She asks, "Who draws the cat here?" No child answers, but they are

  looking at Mike. So she says, "Can you answer the question, Mike?" He has to say, "I am sorry, I do."  

 "You are the worst child in your class!" "It's not my fault. Why do you let Bill leave?"

1. The children begin to laugh because _____.

    A. Mike wants to be a teacher            

    B. Mike draws a cat on the teacher's desk

    C. Mike doesn't find Miss White behind him  

    D. Mike wants to clean the blackboard

2. The other children look at Mike because _____.

    A. Mike looks like a teacher                

    B. they think Mike does wrong

    C. they thinks Mike does right              

    D. Mike is the tallest of class.

3. Miss White thinks there are _____ students in Mike's class.

    A. 32    

    B. 33    

    C. 34   

    D. 35

4. The words "worst" and "fault" in the story mean _____ in Chinese.

    A. 最好的, 过错    

    B. 最坏的, 过错    

    C. 最好的, 功劳    

    D. 最坏的, 功劳

选择题