基于Java Socket的网络聊天系统的设计

开发的网络聊天系统是基于开放的Java应用程序设计的,能动态、实时地完成信息的传递,且具有高效的交互性,能更有效地处理客户请求,易于维护和更新.系统采用客户机/服务器的架构模式,客户端通过Socket发送信息给服务器,从而实现多点对多点的聊天.系统界面采用Java中的Swing技术来实现.     

网络即时通讯系统

网络即时通讯系统是通过网络实现在线交流的工具软件。系统基于Client/Server架构,用Java语言和SQL 2000作为开发工具,采用Socket编程和多线程技术设计并实现。系统能够完成用户注册、用户登录、消息通信、好友管理、在线聊天等功能。     

基于Java多线程技术网络聊天程序的设计与实现

当前网络十分发达,网络聊天软件也十分盛行,本文基于Java平台,使用多线程技术,采用TCP协议来实现网络聊天程序,为Java平台下的数据传输类系统开发提供了底层的技术支持。     

基于XMPP协议文件传输的研究与实现

在C/S网络模式下,利用Java语言及开源的开发工具Eclipse,结合SWT控件实现基于XMPP协议的即时通信系统;系统主要包括单人聊天、群聊天、视频和语音聊天、文件传输、数字签名、广告播放等功能模块;主要介绍文件传输部分——用于系统中传输文件和数字签名文件;通过实例应用表明,采用基于XMPP协议进行XML流的传输优于其它IM通用协议。     

基于Java聊天系统的设计与实现

分析了客户/服务器模式和Socket编程的基本原理,阐述了在Java环境下应用Socket技术实现网络聊天系统的基本思想和功能,并给出了具体的实现代码.     

运用Socket及多线程技术实现一对多的在线聊天程序

实现基于网络的在线聊天程序的关键是建立用户之间交流的数据通道,可以通过基于Java的Socket技术实现数据通道的建立与信息交换,用多线程技术实现多个客户端到服务器的多对一的聊天功能。     

基于Java Socket的聊天室系统设计与实现

Socket(套接字)是一种网络编程接口.介绍了Socket的通信机制,建立了一个基于Java Socket的聊天室系统.该系统能够实现公共聊天和私人聊天,允许在网络上有多个Server,客户端根据输入Server的IP地址连入相应的服务器参与聊天活动,服务器上显示当前在线的用户信息,并对用户进入或断开的信息加以显示.     

基于JMF的多人视频聊天软件的设计与实现

多人视频聊天软件是网络环境与网络技术发展的产物,具有很高的应用需求和广阔的应用前景.JMF(Java媒体框架)是Java语言的扩展,专门用来处理时基媒体数据和实时媒体流.通过介绍JMF应用编程接口的结构特点,详细阐述了当前Internet网络多人视频聊天软件的工作原理、关键技术,及其基于JMF的具体实现.该软件具有跨平台可移植性.     

基于Java的RMI技术的研究与应用

Java语言因其突出的简单性、可移植性、安全性和支持并发机制的程序设计等优良特性,使它成为基于Internet网络应用开发的首选语言。其价值主要体现在强大的开发分布式网络应用的能力上,而RMI则是开发纯Java的网络分布式应用系统的核心解决方案。通过对Java RMI分布式应用程序实例的分析,给出了Java RMI分布式应用程序的实现和运行方法,为Java语言应用开发人员提供参考。     

基于Java三层架构的网络文件传输系统的研究与实现

本文在分析Java三层架构WebWork、Spring、Hibernate的特点和优点的基础上,提出并设计了基于Java三层架构的网络文件传输系统的网络结构、系统逻辑架构、系统安全设计等内容,分析了其开发效率高等优点,实现了一种可扩展的灵活的网络文件传输系统。     

基于FPGA的Java处理器设计

针对Java技术在嵌入式领域的广泛应用,设计了一个适用于低端嵌入式设备的32位环境的Java处理器JPOR。该处理器由FPGA芯片实现,采用一种新的Java栈结构,指令系统简洁,可以直接执行Java字节码,能够对实时Java规范(RTSJ)提供有效支持。在Xilinx SPARTAN-3平台上通过了功能仿真,表明该Java处理器能够在低成本的FPGA芯片中实现。     

Java技术在嵌入式系统中的作用探究简

Java语言是在C＋＋语言的基础上来进行改变而成的,其是属于一种新型的计算机编程语言,在计算机技术的发展过程中,Java语言逐渐得到了广泛的应用,Java技术不但是一种编程语言,更是一个开发平台。Java技术在使用过程中具有较高的安全性、可移植性、稳定性及通用性,因此在嵌入式系统中有广泛的应用。本文通过Java技术、Java卡、J2ME的介绍,来分析Java技术在嵌入式系统中具有的作用。     

J-SEAL2—A Secure High-Performance Mobile Agent System

Even though the advantages of mobile agents for distributed electronic commerce applications have been highlighted in numerous research works, mobile agent applications are not in widespread use today. For the success of mobile agent applications, secure, portable, and efficient execution platforms for mobile agents are crucial. However, popular mobile agent systems do not meet the high security requirements of electronic commerce applications, are not portable, or cause high overhead. Currently, the majority of mobile agent platforms is based on Java. These systems simply rely on the security model of Java, although it is not suited to protect agents and service components from each other.In contrast, J-SEAL2 is a mobile agent system designed to meet the high security, portability, and performance requirements of large-scale electronic commerce applications. J-SEAL2 extends the Java environment with a model of strong protection domains. The core of the system is a micro-kernel fulfilling the same functions as a traditional operating system kernel: protection, communication, domain termination, and resource control. For portability reasons, J-SEAL2 is implemented in pure Java. This paper focuses on the design of the new communication model in J-SEAL2, which allows convenient, efficient, and mediated communication in a hierarchy of strong protection domains.     

Device level communication libraries for high‐performance computing in Java

Since its release, the Java programming language has attracted considerable attention from the high‐performance computing (HPC) community because of its portability, high programming productivity, and built‐in multithreading and networking support. As a consequence, several initiatives have been taken to develop a high‐performance Java message‐passing library to program distributed memory architectures, such as clusters. The performance of Java message‐passing applications relies heavily on the communications performance. Thus, the design and implementation of low‐level communication devices that support message‐passing libraries is an important research issue in Java for HPC. MPJ Express is our Java message‐passing implementation for developing high‐performance parallel Java applications. Its public release currently contains three communication devices: the first one is built using the Java New Input/Output (NIO) package for the TCP/IP; the second one is specifically designed for the Myrinet Express library on Myrinet; and the third one supports thread‐based shared memory communications. Although these devices have been successfully deployed in many production environments, previous performance evaluations of MPJ Express suggest that the buffering layer, tightly coupled with these devices, incurs a certain degree of copying overhead, which represents one of the main performance penalties. This paper presents a more efficient Java message‐passing communications device, based on Java Input/Output sockets, that avoids this buffering overhead. Moreover, this device implements several strategies, both in the communication protocol and in the HPC hardware support, which optimizes Java message‐passing communications. In order to evaluate its benefits, this paper analyzes the performance of this device comparatively with other Java and native message‐passing libraries on various high‐speed networks, such as Gigabit Ethernet, Scalable Coherent Interface, Myrinet, and InfiniBand, as well as on a shared memory multicore scenario. The reported communication overhead reduction encourages the upcoming incorporation of this device in MPJ Express ( http://mpj‐express.org ). Copyright © 2011 John Wiley & Sons, Ltd.     

离线匿名电子现金系统的设计与实现

本文利用Java Applet和Java Network Launch Protocol等技术设计和实现了一个基于RSA盲数字签名的离线匿名的电子现金系统。系统采用B／S和C／S相结合的架构，可以方便进行Web在线支付和点对点支付。系统通过数字证书提供对用户和银行的强身份认证，用户在银行网站进行存取款和在商家网站进行支付，通过SSL协议来保证通信数据的安全，同时用户数据以加密的方式保存在本地磁盘，并可方便地移植到智能卡设备。     

基于Java多线程的并发机制的研究和实现

针对高可靠性、高质量的Java并行多任务程序设计,分析了Java多线程机制的原理及其实现技术,研究了程序并发过程中的同步机制和交互通信机制,比较了基于操作系统级和基于Java多线程级并发机制的实现结构,总结了并发程序中死锁预防的一些编程规则和策略。所构造的一个具有完全意义上的并发同步的框架实例有一定的实用价值。     

Java supervenience

This paper reports on the development of a language construct designed to solve certain problems in composability at the level of object-oriented programming languages. Features were chosen to investigate how much compositional functionality could be added to core Java with as small a change as possible and in an additive manner. A fairly elegant and effective syntax on core Java resulted in reducing the clutter of the "mechanics" of composition. This construct features eliminating runtime cast and null exceptions within the construct, and the option of parametric covariant override. It does so while avoiding undesirable restrictions or new frameworks. Recently, new techniques intended to improve the composability of software components in the Java ecosystem have been vigorously pursued. Proposals take on the objectives of composition in largescale systems and enterprise applications but often implement on conventional object-oriented languages which face the same kinds of problems from the ground up. Benefitting from those experiences, the present work seeks to provide core Java-level solutions to problems that are analogous to those at the higher-levels. The supervenience construct described in this paper is based on a well-established formulation for composing a relationship over classes with some common behavioral elements, their behavioral intersection. The narrow concern of this construct is the sound composition of components across class families while eliminating certain barriers to runtime type-safety in core Java. The supervenience construct has been applied to certain classic problems and key case studies in composability and extensibility which represent fundamental issues that emerge at every level. The implementation requires no installed runtime frameworks and no changes to the JVM or type system of core Java. It is designed to deploy stand-alone or later integrate with the standard Java compiler and IDEs. The continuing research is now focusing on a more formal proof of its type-safety, applying the reference implementation to mid-scale and distributed applications.     

Java虚拟机的硬件实现研究

Java语言的平台无关性使其正在进入嵌入式系统领域，但Java的性能问题一直是Java应用关注的焦点。JIT技术的运用在一定程度上提高了Java的执行速度，但在对实时性要求高和存储受限的嵌入式等系统的运用中仍然难以满足其要求。文章提出了一种基于硬件的解决方法——Java处理器，它能直接执行Java字节码，从而提高Java的性能，以用于实时及嵌入式系统。     

Model Checking Programs

The majority of work carried out in the formal methods community throughout the last three decades has (for good reasons) been devoted to special languages designed to make it easier to experiment with mechanized formal methods such as theorem provers, proof checkers and model checkers. In this paper we will attempt to give convincing arguments for why we believe it is time for the formal methods community to shift some of its attention towards the analysis of programs written in modern programming languages. In keeping with this philosophy we have developed a verification and testing environment for Java, called Java PathFinder (JPF), which integrates model checking, program analysis and testing. Part of this work has consisted of building a new Java Virtual Machine that interprets Java bytecode. JPF uses state compression to handle big states, and partial order and symmetry reduction, slicing, abstraction, and runtime analysis techniques to reduce the state space. JPF has been applied to a real-time avionics operating system developed at Honeywell, illustrating an intricate error, and to a model of a spacecraft controller, illustrating the combination of abstraction, runtime analysis, and slicing with model checking.     

基于JMX/JDMK技术的SNMP分级代理

JMX是新的Java平台标准扩展，它支持现有的SNMP网络管理协议。Java DMK是建立在JMX架构之上Java系列的一个部分，并与该架构兼容。在探讨JMX／JDMK技术提供的分级代理方法的基础上，设计出SNMP分级代理体系，以构建灵活、有效及分布的仍以SNMP为基础的网络管理系统。