基于java技术的邮件系统设计与实现

论文字数:17915,页数:38

摘  要

 电子邮件(简称E-mai1)又称电子信箱、电子邮政，它是—种用电子手段提供信息交换的通信方式。它是全球多种网络上使用最普遍的一项服务。这种非交互式的通信,加速了信息的交流及数据传送,它是—个简易、快速的方法。通过连接全世界的Internet,实现各类信号的传送、接收、存贮等处理,将邮件送到世界的各个角落。到目前为止,可以说电子邮件是Internet资源使用最多的一种服务，E-mai1不只局限于信件的传递,还可用来传递文件、声音及图形、图像等不同类型的信息。
 本邮件系统采用基于线程池的SMTP服务器、POP3服务器架构，支持软件升级，构建适合中小型企业应用的具有高性能、高可靠和卓越的安全性的跨平台的专业邮件系统。另外系统还可以作为嵌入式开发的参考系统，便于以后可以更广范围的应用扩充。邮件系统采用适合用于实现高性能的邮件服务器的基于线程池的SMTP服务器、POP3服务器架构，采用并实现了线程驱动机制，所有操作使用线程运行；服务器内部实现了域名解析机制，并实现域名/地址缓存；将数据库技术引入到用户的管理模块。使用的数据库动态配置技术，使用户管理模块能够独立于数据库；用户数据缓存减小了系统的操作，有助于系统性能的提高；利用了Java语言作为开发工具，使系统具有了跨平台能力。Java语言的垃圾回收机制，既防止了内存泄漏，又提高了服务器的性能。

关键词：电子邮件，日志管理，JAVAMAIL，线程池，域名解析，邮件发送和接收协议

Abstract

 E-mail is a kind of electronic means of information exchange means of communication. It is a global network on a variety of the most common use of the service. This non-interactive communications and accelerate the exchange of information and data transmission, it is - a simple, fast way. Connect the world through the Internet, the realization of various types of signal transmission, receiving, storage and other processing, e-mail will be sent to all corners of the world. So far, e-mail can be said is the most used Internet resources as a service, E-mai1 not limited to letters of transfer, can also be used to transfer files, sounds and graphics, images and other different types of information
After the development of the solution, the essay brings the plan the system to betrue,and tests the real system either. Most capability of the system meets ouranticipation.At the end of the essay,there is a detailed demostration of the real system. Aimed at the problems above, A cross-platform mail system uses Java to realize. The work platform of this system adopts Unix system, offering the thorough stability guarantee for service system of mail; Adopts SMTP server、POP3 server, support the software to be upgraded .The specialized mail system is structured for small and medium enterprise, which features high performance, high reliability and significant security with self-property right. In addition, the system can also be as the reference system of embedded development .The mail system use thread-driven mechanism; every operation is performed by thread; the server internally supports domain resolution, and implements domain/address caches; and the user management module uses the techniques used in database. The dynamic database configuration technique makes the user management independent of database; user data caches reduce system I/O, and improve the system performance; using Java as implementation tool makes the system cross-platform. The garbage collector of Java not only prevents memory leakage, but also improves the system performance.

Keywords:  Email, Log management, Thread pool, Domain Name System  resolving,
            JAVAMAIL，Simple Mail Transfer Protocol, Post Office Protocol version
目  录

摘  要 I
Abstract II
第1章 绪 论 1
1.1 引言 1
1.2 电子邮件系统的工作原理 2
1.3 主要工作与本文组织 3
1.4 本章小结 4
第2章 系统框架及特色 5
2.1 系统模块结构 5
2.2 电子邮件系统相关协议分析 6
2.2.1 Internet邮件发送和接收协议——SMTP协议 7
2.2.2 Internet邮件提取协定 8
2.2.3 POP3协议 9
2.2.4 IMAP协议 10
2.3 电子邮件系统的特点 12
2.4 小结 12
第3章 电子邮件服务器系统结构 13
3.1 I/O模型分析 13
3.2 几种服务器结构研究分析 14
3.2.1 多进程并发服务器 15
3.2.1.1 单个请求/进程 15
3.2.1.2 进程池 15
3.2.2 多线程并发服务器 17
3.2.2.1 单个请求/线程 17
3.2.2.2 线程池 17
3.2.3 单进程并发服务器 18
3.3 设计方案的选择 19
3.4 小结 20
第4章 电子邮件服务器的实现 21
4.1 功能/性能目标 21
4.2 系统模块构成及实现 21
4.2.1 用户管理 22
4.2.3 POP3模块 22
4.3 小结 25
第5章 功能及性能测试 26
5.1 项目测试 26
5.1.1 登入主界面 26
5.1.2 发送邮件测试 26
5.1.3 项目验证 28
5．2 小结 29
第6章 结束语 30
第7章 致  谢 32
第8章 参考文献 33