计算机类外文文献翻译---Java核心技术.doc

本科毕业论文 外文文献及译文 文献、资料题目：Core Java? Volume II–Advanced Features 文献、资料来源：著作 文献、资料发表（出版）日期：2008.12.1 院 （部）： 计算机科学与技术学院 专 业： 网络工程 班 级： 网络082 姓 名： 刘治华 学 号： 指导教师： 许丽娜 翻译日期： 2012.5.10 外文文献：　 Core Java? Volume II–Advanced Features When Java technology first appeared on the scene, the excitement was not about a well-crafted programming language but about the possibility of safely executing applets that are delivered over the Internet (see Volume I, Chapter 10 for more information about applets). Obviously, delivering executable applets is practical only when the recipients are sure that the code cant wreak havoc on their machines. For this reason, security was and is a major concern of both the designers and the users of Java technology. This means that unlike other languages and systems, where security was implemented as an afterthought or a reaction to break-ins, security mechanisms are an integral part of Java technology. Three mechanisms help ensure safety: ? Language design features (bounds checking on arrays, no unchecked type conversions, no pointer arithmetic, and so on). ? An access control mechanism that controls what the code can do (such as file access, network access, and so on). ? Code signing, whereby code authors can use standard cryptographic algorithms to authenticate Java code. Then, the users of the code can determine exactly who created the code and whether the code has been altered after it was signed. Below, youll see the cryptographic algorithms supplied in the java.security package, which allow for code signing and user authentication. As we said earlier, applets were what started the craze over the Java platform. In practice, people discovered that although they could write animated applets like the famous nervous text applet, applets could not do a whole lot of useful stuff in the JDK 1.0 security model. For example, because applets under JDK 1.0 were so closely supervised, they couldnt do much good on a corporate intranet, even thoug