实时Java平台的类预处理器研究

设计并实现一种针对32 bit嵌入式实时Java平台的类预处理器,通过把标准class文件转换成适合Java处理器——Jpor32直接执行的内存映像,将在运行时动态装载和解析class的工作交由类预处理器提前完成,从而消除影响运行时实时性的一些操作,并降低Java处理器的设计复杂性。     

实时Java平台的类预处理器研究

设计并实现一种针对32 bit嵌入式实时Java平台的类预处理器,通过把标准class文件转换成适合Java处理器——Jpor32直接执行的内存映像,将在运行时动态装载和解析class的工作交由类预处理器提前完成,从而消除影响运行时实时性的一些操作,并降低Java处理器的设计复杂性。     

A framework for specifying and verifying the behaviour of open systems

Coding no longer represents the main issue in developing software applications. It is the design and verification of complex software systems that require to be addressed at the architectural level, following methodologies which permit us to clearly identify and design the components of a system, to understand precisely their interactions, and to formally verify the properties of the systems. Moreover, this process is made even more complicated by the advent of the “network-centric” model of computation, where open systems dynamically interact with each other in a highly volatile environment. Many of the techniques traditionally used for closed systems are inadequate in this context.We illustrate how the problem of modeling and verifying behavioural properties of open system is addressed by different research fields and how their results may contribute to a common solution. Building on this, we propose a methodology for modeling and verifying behavioural aspects of open systems. We introduce the IP-calculus, derived from the π-calculas process algebra so as to describe behavioural features of open systems. We define a notion of partial correctness, acceptability, in order to deal with the intrinsic indeterminacy of open systems, and we provide an algorithmic procedure for its effective verification.     

Java语言与Java技术

介绍Ｊａｖａ语言对业界的影响，Ｊａｖａ平台及当前正在发展着的Ｊａｖａ技术。     

基于OPC和Java的远程监控系统架构研究与设计

目前,OPC技术在过程控制系统中获得了广泛的应用,但OPC技术以Microsoft公司的OLE/COM技术为基础,应用基本上仍然局限在Windows系统平台,而目前企业级的上层应用系统大多采用的是J2EE体系结构,如何在J2EE体系结构下应用OPC技术这将是本文要讨论的问题。本文探讨了Java与OPC相结合的技术,并构建了一种基于OPC和Java技术的分布式远程监控系统。这种系统具有良好的开放性、可扩展性和平台无关性特点。     

可预测性CER-实时Java模型研究与应用

在分析现有实时Java规范和开发模型局限性基础上,提出了一种面向嵌入式高可靠实时系统开发的CER-实时Java简化模型。该模型采用三层开发结构,即创建层、执行层和回收层。创建层完成线程和对象的分组创建和启动,执行层执行被启动的线程,回收层负责垃圾定期回收。其中,线程分组创建、定期垃圾回收机制以及通过一部分类的简化定义等,既能保证程序运行的可预测性,同时又能降低内存使用量和简化模型复杂性。     

Requirements-document-based prototyping of CARA software

Computer-aided prototyping evaluates and refines software requirements by defining requirements specifications, designing underlying compositional architecture, doing restricted real-time scheduling, and constructing a prototype by using reusable executable software components. This paper presents a case study of the Computer Assisted Resuscitation Algorithm (CARA) software for a casualty intravenous fluid infusion pump and explores the effectiveness of performing rapid prototyping with parallel conceptualization to expose requirements issues. Using a suite of prototyping tools, five different design model alternatives are generated based on the analysis of customer requirements documents. Further comparison is conducted with specific focus on a sample of comparative criteria: simplicity of design, safety aspects, requirements coverage, and enabling architecture. The case study demonstrates the usefulness of comparative rapid prototyping for revealing the omissions and discrepancies in the requirements document. The study also illustrates the efficiency of creating/modifying parallel models and reason for their complexity by using the tool suite. Additional enhancements for the prototyping suite are highlighted.     

Measuring a Java Test Suite Coverage Using JML Specifications

We propose in this paper a way to measure the coverage of a Java test suite by considering the JML specification associed to the Java program under test. This approach is based on extracting a predicate-based graph from the JML method specifications. We then measure the coverage of this latter w.r.t. nodes of the graph that are visited by the test suite. In addition, we propose to check whether the test suite satisfies classical condition coverage criteria. We also introduce a tool, to be used as precompiler for Java, that is in charge of measuring and reporting the coverage according to these criteria.     

Java虚拟机中Java栈以及相关指令的实现

Java栈是Java虚拟机中运行时数据区的主要组成部分。大部分虚拟机指令的操作都与Java栈中的框架相关联。该文描述了Java栈在Java虚拟机运行中所起的作用,自行设计了一种Java栈的数据结构,提出了一些具有代表性的字节码指令的实现方法。同时总结了Java栈对虚拟机运行效率的影响。     

Over-exposed classes in Java: An empirical study

Java access modifiers regulate interactions among software components. In particular, class modifiers specify which classes from a component are publicly exposed and therefore belong to the component public interface. Restricting the accessibility as specified by a programmer is key to ensure a proper software modularity. It has been said that failing to do so is likely to produce maintenance problems, poor system quality, and architecture decay. However, how developers uses class access modifiers or how inadequate access modifiers affect software systems has not been investigated yet in the literature.In this work, we empirically analyze the use of class access modifiers across a collection of 15 Java libraries and 15 applications, totaling over 3.6M lines of code. We have found that an average of 25% of classes are over-exposed, i.e., classes defined with an accessibility that is broader than necessary. A number of code patterns involving over-exposed classes have been formalized, characterizing programmers׳ habits. Furthermore, we propose an Eclipse plugin to make component public interfaces match with the programmer׳s intent.     

基于Java的图片管理信息系统的设计与实现

结合图片管理系统的开发，给出了在大型数据库管理系统支持下，基于客户机／服务器模式开发管理信息系统的一种方法，并详细介绍了所开发系统的主要功能模块。该系统不仅具备完善的图片数据录入、更新、删除、条件检索等功能，而且进行了“图片专题”功能的开发，为扩展图片管理信息系统的应用模式进行了新的尝试。     

Java死锁的产生及解决机制

本文从线程和角度深入分析了Java中死锁产生的原因，并提出了Java死锁解决的可行性方案。     

数据结构在Java语言中的实现

通过实例详细分析了数据结构中数据和操作在Java环境中的实现过程,从而学会编写更加高效的程序.     

Java中构建插件兼容对象

本文通过实例介绍Java中构建插件兼容对象的方法,提出将"黑盒"操作与面向对象的多态性结合起来有助于分析、计划和编写程序代码。     

A Type System for the Java Bytecode Language and Verifier

The Java Virtual Machine executes bytecode programs that may have been sent from other, possibly untrusted, locations on the network. Since the transmitted code may be written by a malicious party or corrupted during network transmission, the Java Virtual Machine contains a bytecode verifier to check the code for type errors before it is run. As illustrated by reported attacks on Java run-time systems, the verifier is essential for system security. However, no formal specification of the bytecode verifier exists in the Java Virtual Machine Specification published by Sun. In this paper, we develop such a specification in the form of a type system for a subset of the bytecode language. The subset includes classes, interfaces, constructors, methods, exceptions, and bytecode subroutines. We also present a type checking algorithm and prototype bytecode verifier implementation, and we conclude by discussing other applications of this work. For example, we show how to extend our formal system to check other program properties, such as the correct use of object locks. This revised version was published online in August 2006 with corrections to the Cover Date.     

基于Java ME和Java EE的移动商务系统设计与实现

随着移动通信广泛应用和电子商务技术的成熟壮大,移动商务已经具备了发展的基础条件,电子商务逐渐向移动商务迁移,但移动商务服务领域仍很薄弱.本文针对移动商务环境,提出了一种基于Java ME和Java EE的移动商务系统架构,并进行系统分析与设计,采用Eclipse、WTK等开发工具编程实现,经过实验证明该系统能够有效地实现移动商务处理,该架构和开发技术可以应用于移动商务服务系统以及其他移动应用系统的构建.     

Java异常处理机制研究

异常处理机制是程序设计语言的主要特征,它为开发稳定的软件系统提供了有力的支持.文章对Java语言的异常处理机制以及异常类的层次进行了详细介绍,提出了Java异常处理策略.     

多层分布式应用系统在Java中的实现

在分析了分布计算、JDBC和RMI等技术的基础上,提出了多层分布式应用系统在Java中的实现模型.同时,由于Java具有跨平台、可移植性、安全高效等强大功能,是开发网络分布式系统的理想工具.     

“Java语言程序设计”课学生能力的培养

本文针对Java语言程序设计课学生的动手能力和自学能力薄弱的问题,结合近年来的教学经验,从课堂教学、阶段性实验、总结性实验、测评和延伸课堂教学五个方面进行了实践探索。