Java and the Internet
If Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming、The answer isn’t immediately obvious if you’re comin g from a traditional programming perspective、Although Java is very useful for solving traditional stand-alone programming problems, it is also important because it will solve programming problems on the World Wide Web、
1.Client-side programming
The Web’s in itial server-browser design provided for interactive content, but the interactivity was completely provided by the server、The server produced static pages for the client browser, which would simply interpret and display them、Basic HTML contains simple mechanisms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server、This submission passes through the Common Gateway Interface (CGI) provided on all Web servers、The text within the submission tells CGI what to do with it、The most common action is to run a program located on the server in a directory that’s typically called “cgi-bin、” (If you watch the address window at the top of your browser when you push a button on a Web page, you can sometimes see “cgi-bin” within all the gobbledygook there、) These programs can be written in most languages、Perl is a common choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardless of processor or operating system、
Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with it、However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is also the problem of
response time、The response of a CGI program depends on how much data must be sent, as well as the load on both the server and the Internet、(On top of this, starting a CGI program tends to be slow、) The initial designers of the Web did not foresee how rapidly this bandwidth would be exhausted for the kinds of applications people developed、For example, any sort of dynamic graphing is nearly impossible to perform with consistency because a GIF be created and moved from the server to the client for each version of the graph、And you’ve no doubt had direct experience with something as simple as validating the data on an input form、You press the submit button on a page; the data is shipped back to the server; the server starts a CGI program that discovers an error, formats an HTML page informing you of the error, and then sends the page back to you; you must then back up a page and try again、Not only is this slow, it’s inelegant、
The solution is client-side programming、Most machines that run Web browsers are powerful engines capable of doing vast work, and with the original static HTML approach they are sitting there, just idly waiting for the server to dish up the next page、Client-side programming means that the Web browser is harnessed to do whatever work it can, and the result for the user is a much speedier and more interactive experience at your Web site、
The problem with discussions of client-side programming i s that they aren’t very different from discussions of programming in general、The parameters are almost the same, but the platform is different: a Web browser is like a limited operating system、In the end, you must still program, and this accounts for the dizzying array of problems and solutions produced by client-side programming、The rest of this section provides an overview of the issues and approaches in client-side programming、
2、Plug-ins
One of the most significant steps forward in client-side programming is the development of the plug-in、This is a way for a programmer to add new functionality to the browser by downloading a piece of code that plugs itself into
the appropriate spot in the browser、It tells the browser “from now on you can perform this new activity、” (You need to download the plug-in only once、) Some fast and powerful behavior is added to browsers via plug-ins, but writing a plug-in is not a trivial task, and isn’t something you’d want to do as part of the process of building a particular site、The value of the plug-in for client-side programming is that it allows an expert programmer to develop a new language and add that language to a browser without the permission of the browser manufacturer、Thus, plug-ins provide a “back door” that allows the creation of new client-side programming languages (although not all languages are implemented as plug-ins)、
3、Scripting languages
Plug-ins resulted in an explosion of scripting languages、With a scripting language you embed the source code for your client-side program directly into the HTML page, and the plug-in that interprets that language is automatically activated while the HTML page is being displayed、Scripting languages tend to be reasonably easy to understand and, because they are simply text that is part of an HTML page, they load very quickly as part of the single server hit required to procure that page、The trade-off is that your code is exposed for everyone to see (and steal)、Generally, however, you aren’t doing amazingly sophistica ted things with scripting languages so this is not too much of a hardship、
This points out that the scripting languages used inside Web browsers are really intended to solve specific types of problems, primarily the creation of richer and more interactive graphical user interfaces (GUIs)、However, a scripting language might solve 80 percent of the problems encountered in client-side programming、Your problems might very well fit completely within that 80 percent, and since scripting languages can allow easier and faster development, you should probably consider a scripting language before looking at a more involved solution such as Java or ActiveX programming、
The most commonly discussed browser scripting languages are JavaScript (which has nothing to do wit h Java; it’s named that way just to grab some of
Java’s marketing momentum), VBScript (which looks like Visual Basic), and Tcl/Tk, which comes from the popular cross-platform GUI-building language、There are others out there, and no doubt more in development、
JavaScript is probably the most commonly supported、It comes built into both Netscape Navigator and the Microsoft Internet Explorer (IE)、In addition, there are probably more JavaScript books available than there are for the other browser languages, and some tools automatically create pages using JavaScript、However, if you’re already fluent in Visual Basic or Tcl/Tk, you’ll be more productive using those scripting languages rather than learning a new one、(You’ll have your hands full dealing with the W eb issues already、)
4、Java
If a scripting language can solve 80 percent of the client-side programming problems, what about the other 20 percent—the “really hard stuff?” The most popular solution today is Java、Not only is it a powerful programming language built to be secure, cross-platform, and international, but Java is being continually extended to provide language features and libraries that elegantly handle problems that are difficult in traditional programming languages, such as multithreading, database access, network programming, and distributed computing、Java allows client-side programming via the applet、
An applet is a mini-program that will run only under a Web browser、The applet is downloaded automatically as part of a Web page (just as, for example, a graphic is automatically downloaded)、When the applet is activated it executes a program、This is part of its beauty—it provides you with a way to automatically distribute the client software from the server at the time the user needs the client software, and no sooner、The user gets the latest version of the client software without fail and without difficult reinstallation、Because of the way Java is designed, the programmer needs to create only a single program, and that program automatically works with all computers that have browsers with built-in Java interpreters、(This safely includes the vast majority of machines、) Since Java is a full-fledged programming language, you can do as
much work as possible on the client before and after making requests of the server、For example, you won’t need to send a request form across the Internet to discover that you’ve gotten a date or some other parameter wrong, and your client computer can quickly do the work of plotting data instead of waiting for the server to make a plot and ship a graphic image back to you、Not only do you get the immediate win of speed and responsiveness, but the general network traffic and load on servers can be reduced, preventing the entire Internet from slowing down、
One advanta ge a Java applet has over a scripted program is that it’s in compiled form, so the source code isn’t available to the client、On the other hand, a Java applet can be decompiled without too much trouble, but hiding your code is often not an important issue、Two other factors can be important、As you will see later in this book, a compiled Java applet can comprise many modules and take multiple server “hits” (accesses) to download、(In Java 1、1 and higher this is minimized by Java archives, called JAR files, that allow all the required modules to be packaged together and compressed for a single download、) A scripted program will just be integrated into the Web page as part of its text (and will generally be smaller and reduce server hits)、This could be important to the responsiveness of your Web site、Another factor is the all-important learning curve、Regardless of what you’ve heard, Java is not a trivial language to learn、If you’re a Visual Basic programmer, moving to VBScript will be your fastest solution, and since it will probably solve most typical client/server problems you might be hard pressed to justify learning Java、If you’re experienced with a scripting language you will certainly benefit from looking at JavaScript or VBScript before committing to Java, since they might fit your needs handily and you’ll be more productive sooner、to run its applets withi
5、ActiveX
To some degree, the competitor to Java is Microsoft’s ActiveX, although it takes a completely different approach、ActiveX was originally a Windows-only
solution, although it is now being developed via an independent consortium to become cross-platform、Effectively, ActiveX says “if your program connects to its environment just so, it can be dropped into a Web page and run under a browser that supports ActiveX、” (IE directly supports ActiveX and Netscape does so using a plug-in、) Thus, ActiveX does not constrain you to a particular language、If, for example, you’re already an experienced Windows programmer using a language such as C++, Visual Basic, or Borland’s Delphi, you can create ActiveX components with almost no changes to your programming knowledge、ActiveX also provides a path for the use of legacy code in your Web pages、
6、Security
Automatically downloading and running programs across the Internet can sound like a virus-builder’s dream、ActiveX especially brings up the thorny issue of security in client-side programming、If you click on a Web site, you might automatically download any number of things along with the HTML page: GIF files, script code, compiled Java code, and ActiveX components、Some of these are benign; GIF files can’t do any harm, and scripting languages are generally limited in what they can do、Java was also designed to run its applets within a “sandbox” of safety, wh ich prevents it from writing to disk or accessing memory outside the sandbox、
ActiveX is at the opposite end of the spectrum、Programming with ActiveX is like programming Windows—you can do anything you want、So if you click on a page that downloads an ActiveX component, that component might cause damage to the files on your disk、Of course, programs that you load onto your computer that are not restricted to running inside a Web browser can do the same thing、Viruses downloaded from Bulletin-Board Systems (BBSs) have long been a problem, but the speed of the Internet amplifies the difficulty、
The solution seems to be “digital signatures,” whereby code is verified to show who the author is、This is based on the idea that a virus works because its creator can be anonymous, so if you remove the anonymity individuals will be
forced to be responsible for their actions、This seems like a good plan because it allows programs to be much more functional, and I suspect it will eliminate malicious mischief、If, however, a program has an unintentional destructive bug it will still cause problems、
The Java approach is to prevent these problems from occurring, via the sandbox、The Java interpreter that lives on your local Web browser examines the applet for any untoward instructions as the applet is being loaded、In particular, the applet cannot write files to disk or erase files (one of the mainstays of viruses)、Applets are generally considered to be safe, and since this is essential for reliable client/server systems, any bugs in the Java language that allow viruses are rapidly repaired、(It’s worth noting that the browser software actually enforces these security restrictions, and some browsers allow you to select different security levels to provide varying degrees of access to your system、)
You might be skeptical of this rather draconian restriction against writing files to your local disk、For example, you may want to build a local database or save data for later use offline、The initial vision seemed to be that eventually everyone would get online to do anything important, but that was soon seen to be impractical (although low-cost “Internet appliances” might someday satisfy the needs of a significant segment of users)、The solution is the “signed applet” that uses public-key encryption to verify that an applet does indeed come from where it claims it does、A signed applet can still trash your disk, but the theory is that since you can now hold the applet creator accountable they won’t do vicious things、Java provides a framework for digital signatures so that you will eventually be able to allow an applet to step outside the sandbox if necessary、Digital signatures have missed an important issue, which is the speed that people move around on the Internet、If you download a buggy program and it does something untoward, how long will it be before you discover the damage? It could be days or even weeks、By then, how will you track down the program that’s done it? And what good will it do you at that point?
7、Internet vs、intranet
The Web is the most general solution to the client/server problem, so it makes sense that you can use the same technology to solve a subset of the problem, in particular the classic client/server problem within a company、With traditional client/server approaches you have the problem of multiple types of client computers, as well as the difficulty of installing new client software, both of which are handily solved with Web browsers and client-side programming、When Web technology is used for an information network that is restricted to a particular company, it is referred to as an intranet、Intranets provide much greater security than the Internet, since you can physically control access to the servers within your company、In terms of training, it seems that once people understand the general concept of a browser it’s much easier for them to deal with differences in the way pages and applets look, so the learning curve for new kinds of systems seems to be reduced、
The security problem brings us to one of the divisions that seems to be automatically forming in the world of client-side programming、If your program is running on the Internet, you don’t know what platform it will be working under, and you want to be extra careful that you don’t disseminate buggy code、You need something cross-platform and secure, like a scripting language or Java、
If you’re running on an intranet, you might have a different set of constraints、It’s not uncommon that your machines could all be Intel/Windows platforms、On an intranet, you’re responsible for the quality of your own code and can repair bugs when they’re discovered、In addition, you might already have a body of legacy code that you’ve been using in a more traditional client/server approach, whereby you must physically install client programs every time you do an upgrade、The time wasted in installing upgrades is the most compelling reason to move to browsers, because upgrades are invisible and automatic、If you are involved in such an intranet, the most sensible approach to take is the shortest path that allows you to use your existing code base, rather than trying to recode your programs in a new language、
When faced with this bewildering array of solutions to the client-side programming problem, the best plan of attack is a cost-benefit analysis、Consider the constraints of your problem and what would be the shortest path to your solution、Since client-side programming is still programming, it’s always a good idea to take the fastest development approach for your particular situation、This is an aggressive stance to prepare for inevitable encounters with the problems of program development、
8、Server-side programming
This whole discussion has ignored the issue of server-side programming、What happens when you make a request of a server? Most of the time the request is simply “send me this file、” Your browser then interprets the some appropriate fashion: as an HTML page, a graphic image, a Java applet, a script program, etc、A more complicated request to a server generally involves a database transaction、A common scenario involves a request for a complex database search, which the server then formats into an HTML page and sends to you as the result、(Of course, if the client has more intelligence via Java or a scripting language, the raw data can be sent and formatted at the client end, which will be faster and less load on the server、) Or you might want to register your name in a database when you join a group or place an order, which will involve changes to that database、These database requests must be processed via some code on the server side, which is generally referred to as server-side programming、Traditionally, server-side programming has been performed using Perl and CGI scripts, but more sophisticated systems have been appearing、These include Java-based Web servers that allow you to perform all your server-side programming in Java by writing what are called servlets、Servlets and their offspring, JSPs, are two of the most compelling reasons that companies who develop Web sites are moving to Java, especially because they eliminate the problems of dealing with differently abled browsers、
9、separate arena: applications
Much of the brouhaha over Java has been over applets、Java is actually a general-purpose programming language that can solve any type of problem—at least in theory、And as pointed out previously, there might be more effective ways to solve most client/server problems、When you move out of the applet arena (and simultaneously release the restrictions, such as the one against writing to disk) you enter the world of general-purpose applications that run standalone, without a Web browser, just like any ordinary program does、Here, Java’s strength is not only in its portability, but also its programm ability、As you’ll see throughout this book, Java has many features that allow you to create robust programs in a shorter period than with previous programming languages、Be aware that this is a mixed blessing、You pay for the improvements through slower execution speed (although there is significant work going on in this area—JDK 1、3, in particular, introduces the so-called “hotspot” performance improvements)、Like any language, Java has built-in limitations that might make it inappropriate to solve certain types of programming problems、Java is a rapidly evolving language, however, and as each new release comes out it becomes more and more attractive for solving larger sets of problems、
Java与因特网
既然Java不过另一种类型的程序设计语言,大家可能会奇怪它为什么值得如此重视,为什么还有这么多的人认为它就是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景,那么答案在刚开始的时候并不就是很明显。Java除了可解决传统的程序设计问题以外,还能解决World Wide Web(万维网)上的编程问题。
1、客户端编程
Web最初采用的“服务器－浏览器”方案可提供交互式内容,但这种交互
能力完全由服务器提供,为服务器与因特网带来了不小的负担。服务器一般为客户浏览器产生静态网页,由后者简单地解释并显示出来。基本HTML语言提供了简单的数据收集机制:文字输入框、复选框、单选钮、列表以及下拉列表等,另外还有一个按钮,只能由程序规定重新设置表单中的数据,以便回传给服务器。用户提交的信息通过所有Web服务器均能支持的“通用网关接口”(CGI)回传到服务器。包含在提交数据中的文字指示CGI该如何操作。最常见的行动就是运行位于服务器的一个程序。那个程序一般保存在一个名为“cgi-bin”的目录中(按下Web页内的一个按钮时,请注意一下浏览器顶部的地址窗,经常都能发现“cgi-bin”的字样)。大多数语言都可用来编制这些程序,但其中最常见的就是Perl。这就是由于Perl就是专为文字的处理及解释而设计的,所以能在任何服务器上安装与使用,无论采用的处理器或操作系统就是什么。
2、插件
朝客户端编程迈进的时候,最重要的一个问题就就是插件的设计。利用插件,程序员可以方便地为浏览器添加新功能,用户只需下载一些代码,把它们“插入”浏览器的适当位置即可。这些代码的作用就是告诉浏览器“从现在开始,您可以进行这些新活动了”(仅需下载这些插入一次)。有些快速与功能强大的行为就是通过插件添加到浏览器的。但插件的编写并不就是一件简单的任务。在我们构建一个特定的站点时,可能并不希望涉及这方面的工作。对客户端程序设计来说,插件的价值在于它允许专业程序员设计出一种新的语言,并将那种语言添加到浏览器,同时不必经过浏览器原创者的许可。由此可以瞧出,插件实际就是浏览器的一个“后门”,允许创建新的客户端程序设计语言(尽管并非所有语言都就是作为插件实现的)。
3、脚本编制语言
插件造成了脚本编制语言的爆炸性增长。通过这种脚本语言,可将用于自己客户端程序的源码直接插入HTML页,而对那种语言进行解释的插件会在HTML页显示的时候自动激活。脚本语言一般都倾向于尽量简化,易于理解。而且由于它们就是从属于HTML页的一些简单正文,所以只需向服务器
中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。
外文资料译文及原文 Java Java I/O 系统 对编程语言的设计者来说，创建一套好的输入输出(I/O)系统，是一项难度极高的任务。 这一点可以从解决方案的数量之多上看出端倪。这个问题难就难在它要面对的可能性太多了。不仅是因为有那么多I/O的源和目地(文件，控制台，网络连接等等)，而且还有很多方法(顺序的『sequential』，随机的『random-access』，缓存的『buffered』，二进制的『binary』，字符方式的『character』，行的『by lines』，字的『by words』，等等)。 Java类库的设计者们用"创建很多类"的办法来解决这个问题。坦率地说Java I/O系统的类实在是太多了，以至于初看起来会把人吓着（但是，具有讽刺意味的是，这种设计实际上是限制了类的爆炸性增长）。此外，Java在1.0版之后又对其I/O类库作了重大的修改，原先是面向byte的，现在又补充了面向Unicode字符的类库。为了提高性能，完善功能，JDK 1.4又加了一个nio(意思是"new I/O"。这个名字会用上很多年)。这么以来，如果你想对Java的I/O 类库有个全面了解，并且做到运用自如，你就得先学习大量的类。此外，了解 I/O类库的演化的历史也是相当重要的。可能你的第一反应是"别拿什么历史来烦我了，告诉我怎么用就可以了！"但问题是，如果你对这段历史一无所知，很快就会被一些有用或是没用的类给搞糊涂了。
本章会介绍Java标准类库中的各种I/O类，及其使用方法。 File 类 在介绍直接从流里读写数据的类之前，我们先介绍一下处理文件和目录的类。 File类有一个极具欺骗性的名字；或许你会认为这是一个关于文件的类，但它不是。你可以用它来表示某个文件的名字，也可以用它来表示目录里一组文件的名字。如果它表示的是一组文件，那么你还可以用list( )方法来进行查询，让它会返回String数组。由于元素数量是固定的，因此数组会比容器更好一些。如果你想要获取另一个目录的清单，再建一个File对象就是了。实际上，叫它"FilePath"可能会更好一些。下面我们举例说明怎样使用这个类及其相关的FilenameFilter接口。 目录列表器 假设你想看看这个目录。有两个办法。一是不带参数调用list( )。它返回的是File对象所含内容的完整清单。但是，如果你要的是一个"限制性列表(restricted list)"的话——比方说，你想看看所有扩展名为.java的文件——那么你就得使用"目录过滤器"了。这是一个专门负责挑选显示File对象的内容的类。 下面就是源代码。看看，用了java.utils.Arrays.sort( )和11章的AlphabeticComparator之后，我们没费吹灰之力就对结果作了排序(按字母顺序)： //: c12:DirList.java // Displays directory listing using regular expressions. // {Args: "D.*\.java"} import java.io.*; import java.util.*; import java.util.regex.*; import com.bruceeckel.util.*; public class DirList { public static void main(String[] args) { File path = new File("."); String[] list; if(args.length == 0) list = path.list(); else list = path.list(new DirFilter(args[0])); Arrays.sort(list, new AlphabeticComparator());
New technique of the computer network Abstract The 21 century is an ages of the information economy, being the computer network technique of representative techniques this ages, will be at very fast speed develop soon in continuously creatively, and will go deep into the people's work, life and study. Therefore, control this technique and then seem to be more to deliver the importance. Now I mainly introduce the new technique of a few networks in actuality live of application. keywords Internet Network System Digital Certificates Grid Storage 1. Foreword Internet turns 36, still a work in progress Thirty-six years after computer scientists at UCLA linked two bulky computers using a 15-foot gray cable, testing a new way for exchanging data over networks, what would ultimately become the Internet remains a work in progress. University researchers are experimenting with ways to increase its capacity and speed. Programmers are trying to imbue Web pages with intelligence. And work is underway to re-engineer the network to reduce Spam (junk mail) and security troubles. All the while threats loom: Critics warn that commercial, legal and political pressures could hinder the types of innovations that made the Internet what it is today. Stephen Crocker and Vinton Cerf were among the graduate students who joined UCLA professor Len Klein rock in an engineering lab on Sept. 2, 1969, as bits of meaningless test data flowed silently between the two computers. By January, three other "nodes" joined the fledgling network.
Java and the Internet If Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn’t immediately obvious if you’re coming from a traditional programming perspective. Although Java is very useful for solving traditional stand-alone programming problems, it is also important because it will solve programming problems on the World Wide Web. 1.Client-side programming The Web’s in itial server-browser design provided for interactive content, but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HTML contains simple mechanisms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server. This submission passes through the Common Gateway Interface (CGI) provided on all Web servers. The text within the submission tells CGI what to do with it. The most common action is to run a program located on the server in a directory that’s typically called “cgi-bin.” (If you watch the address window at the top of your browser when you push a button on a Web page, you can sometimes see “cgi-bin” within all the gobbledygook there.) These programs can be written in most languages. Perl is a common choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardless of processor or operating system. Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with it. However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is also the problem of response time. The response of a CGI program depends on how much data must
英文翻译 A comprehensive overview of substations Along with the economic development and the modern industry developments of quick rising, the design of the power supply system become more and more completely and system. Because the quickly increase electricity of factories, it also increases seriously to the dependable index of the economic condition, power supply in quantity. Therefore they need the higher and more perfect request to the power supply. Whether Design reasonable, not only affect directly the base investment and circulate the expenses with have the metal depletion in colour metal, but also will reflect the dependable in power supply and the safe in many facts. In a word, it is close with the economic performance and the safety of the people. The substation is an importance part of the electric power system, it is consisted of the electric appliances equipments and the Transmission and the Distribution. It obtains the electric power from the electric power system, through its function of transformation and assign, transport and safety. Then transport the power to every place with safe, dependable, and economical. As an important part of power’s transport and control, the transformer substation must change the mode of the traditional design and control, then can adapt to the modern electric power system, the development of modern industry and the of trend of the society life. Electric power industry is one of the foundations of national industry and national economic development to industry, it is a coal, oil, natural gas, hydropower, nuclear power, wind power and other energy conversion into electrical energy of the secondary energy industry, it for the other departments of the national economy fast and stable development of the provision of adequate power, and its level of development is a reflection of the country's economic development an important indicator of the level. As the power in the industry and the importance of the national economy, electricity transmission and distribution of electric energy used in these areas is an indispensable component.。Therefore, power transmission and distribution is critical. Substation is to enable superior power plant power plants or power after adjustments to the lower load of books is an important part of power transmission. Operation of its functions, the capacity of a direct impact on the size of the lower load power, thereby affecting the industrial production and power consumption.Substation system if a link failure, the system will protect the part of action. May result in power outages and so on, to the production and living a great disadvantage. Therefore, the substation in the electric power system for the protection of electricity reliability,
中文翻译 基于Java技术的Web应用设计模型的比较研究 来源：School of Computer Science and Engineering University of New South Wales Sydney, NSW 2052, Australia 作者：Budi Kurniawan and Jingling Xue 摘要 Servlet技术是在建立可扩展性Web应用中被应用最广泛的技术。在运用JAVA技术开发Web应用中有四种模型,分别是:Model 1、Model 2、Struts和JavaServer Faces JSF。Model 1使用一连串的JSP页面，Model 2采用了模型，视图，控制器MVC模式。Struts是一个采用了Model 2设计模型的框架，JSF是一种支持ready-to-use组件来进行快速Web应用开发的新技术。Model 1对于中等和大型的应用来说很难维护，所以不推荐使用。本文通过利用Model 2、Struts和JSF这三种模型分别构建三个不同版本的在线商店应用程序来比较和评价这三种模型在应用程序开发和性能上的差异。 1.绪论 当今Web应用是一种展现动态内容的最普遍的方式。构建Web应用有许多种方法，其中最流行的是Servlet技术。这种技术的流行是因为它比CGI、PHP等其他技术更具优越性。然而Servlet对于开发来说还是麻烦的，因为它在传送HTML 标签时需要程序员将他们组合成为一个字符串对象，再将这个对象传给浏览器。同样的，对于输出的一个很小的改动也要求Servlet被重新编译。基于这个原因SUN 公司发明了JavaServer Pages JSP技术。JSP允许HTML标签和Java代码混合在
第一篇： 航空博物馆与航空展示公园 巴特罗米耶杰·基谢列夫斯基 飞翔的概念、场所的精神、老机场的建筑---克拉科夫新航空博物馆理性地吸取了这些元素，并将它们整合到一座建筑当中。Rakowice-Czyzyny机场之前的旧飞机修理库为新建筑的平面和高度设定了模数比例。在此基本形态上进一步发展，如同裁切和折叠一架纸飞机，生成了一座巨大的建筑。其三角形机翼是由混凝土制成，却如同风动螺旋桨一样轻盈。这个机翼宽大通透，向各个方向开敞。它们的形态与组织都是依据内部功能来设计的。机翼部分为3个不平衡的平面，使内外景观在不断变化中形成空间的延续性，并且联系了建筑内的视觉焦点和室外的展览区。 新航空展示公园的设计连接了博物馆的8栋建筑和户外展览区，并与历史体验建立联系。从前的视觉轴线与通道得到尊重，旧的道路得到了完善，朝向飞机场和跑道的空间被限定出来。每栋建筑展示了一个主题或是一段飞行史。建筑周围伸展出巨大的平台，为特殊主题的室外展览提供了空间。博物馆容纳了超过150架飞机、引擎、飞行复制品、成套的技术档案和历史图片。这里的特色收藏是飞机起源开始的各种飞行器，如Jatho1903、Grade1909、莱特兄弟1909年的飞机模型和1911年的鸽式单翼机。 The first passage: Museum for aviation and aviation exhibition park Bartiomiej Kislelewski The idea of flying, the spirit of place, the structure of the historic airfield – the new Museum of Aviation in Krakow takes up these references intellectually and synthesizes them into a building. The old hangars of the former airport Rakowice Czyzyny set the modular scale for the footprint and the height of the new building. Developed from this basic shape, as if cut out and folded like a paper airplane, a large structure has been generated, with triangular wings made of concrete and yet as light as a wind-vane propeller. The wings are generously glazed and open in all directions. Their form and arrangement depend on the interior uses. In the floor plans of the wings, the three offset
文献来源：Bruce Eckel.Thinking in Java [J]. Pearson Higher Isia Education,2006-2-20. Java编程思想 (Java和因特网) 既然Java不过另一种类型的程序设计语言，大家可能会奇怪它为什么值得如此重视，为什么还有这么多的人认为它是计算机程序设计的一个里程碑呢？如果您来自一个传统的程序设计背景，那么答案在刚开始的时候并不是很明显。Java除了可解决传统的程序设计问题以外，还能解决World Wide Web(万维网) 上的编程问题。 1、客户端编程 Web最初采用的“服务器－浏览器”方案可提供交互式内容，但这种交互能力完全由服务器提供，为服务器和因特网带来了不小的负担。服务器一般为客户浏览器产生静态网页，由后者简单地解释并显示出来。基本HTML语言提供了简单的数据收集机制：文字输入框、复选框、单选钮、列表以及下拉列表等，另外还有一个按钮，只能由程序规定重新设置表单中的数据，以便回传给服务器。用户提交的信息通过所有Web服务器均能支持的“通用网关接口”（CGI）回传到服务器。包含在提交数据中的文字指示CGI该如何操作。最常见的行动是运行位于服务器的一个程序。那个程序一般保存在一个名为“cgi-bin”的目录中（按下Web页内的一个按钮时，请注意一下浏览器顶部的地址窗，经常都能发现“cgi-bin”的字样）。大多数语言都可用来编制这些程序，但其中最常见的是Perl。这是由于Perl是专为文字的处理及解释而设计的，所以能在任何服务器上安装和使用，无论采用的处理器或操作系统是什么。 2、脚本编制语言 插件造成了脚本编制语言的爆炸性增长。通过这种脚本语言，可将用于自己客户端程序的源码直接插入HTML页，而对那种语言进行解释的插件会在HTML 页显示的时候自动激活。脚本语言一般都倾向于尽量简化，易于理解。而且由于它们是从属于HTML页的一些简单正文，所以只需向服务器发出对那个页的一
外文翻译 外文资料： Robots First, I explain the background robots, robot technology development. It should be said it is a common scientific and technological development of a comprehensive results, for the socio-economic development of a significant impact on a science and technology. It attributed the development of all countries in the Second World War to strengthen the economic input on strengthening the country's economic development. But they also demand the development of the productive forces the inevitable result of human development itself is the inevitable result then with the development of humanity, people constantly discuss the natural process, in understanding and reconstructing the natural process, people need to be able to liberate a slave. So this is the slave people to be able to replace the complex and engaged in heavy manual labor, People do not realize right up to the world's understanding and transformation of this technology as well as people in the development process of an objective need. Robots are three stages of development, in other words, we are accustomed to regarding robots are divided into three categories. is a first-generation robots, also known as teach-type robot, it is through a computer, to control over one of a mechanical degrees of freedom Through teaching and information stored procedures, working hours to read out information, and then issued a directive so the robot can repeat according to the people at that time said the results show this kind of movement again, For example, the car spot welding robots, only to put this spot welding process, after teaching, and it is always a repeat of a work It has the external environment is no perception that the force manipulation of the size of the work piece there does not exist, welding 0S It does not know, then this fact from the first generation robot, it will exist this shortcoming, it in the 20th century, the late 1970s, people started to study the second-generation robot, called Robot with the feeling that This feeling with the robot is similar in function of a certain feeling, for
毕业设计(论文)外文资料翻译 系：计算机系 专业：计算机科学与技术 姓名： 学号： 外文出处：Ghosh,D..Java Object-oriented (用外文写) programming[J]. IEEE Transactions on Software Engineering,2009, 13(3):42-45. 附件： 1.外文资料翻译译文；2.外文原文。
注：请将该封面与附件装订成册。
附件1：外文资料翻译译文 Java的面向对象编程 ——面向对象编程和它的关键技术—继承和多态性 软件的重用可以节省程序开发时间。它鼓励重复使用已经调试好的高质量的软件，从而减少系统运行后可能出现的问题。这些都是令人振奋的可能性。多态性允许我们用统一的风格编写程序，来处理多种已存在的类和特定的相关类。利用多态性我们可以方便地向系统中添加新的功能。继承和多态对于解决软件的复杂性是一种有效可行的技术。当创建一个新的类时，而不用完整的写出新的实例变量和实例方法，程序员会指定新的类继承已定义的超类的实例变量和实例方法。这个新的类被称为一个子类。每个子类本身将来亦可有新的子类，而其本身将成为父类。一个类的直接父类就是该类所直接继承的类（通过关键字extends继承）。一个间接超类是通过从两级或更多级以上的类继承而来的。例如，从类JApplet（包javax.swing 中）扩展来的类Applet（包java.applet）。一个类单一的从一个父类继承而来。 Java 不支持多重继承（而C++可以），但它支持接口的概念。接口可以使Java实现许多通过多重继承才能实现的优点而没有关联的问题。我们将在本章讨论的接口的详细内容。我们会给出创建和使用接口的一般规律和具体实例。一个子类通常添加自己的实例变量和自己的实例方法，因此子类通常比父类大。一个子类比它的父类更具体并且代表一组更小、更专业的对象。通过单一继承，子类在开始时拥有父类的所有特性。继承性真正的力量在于它可以在定义子类时增加或取代从超类中继承来的特征。每个子类对象也是该类的父类的对象。例如，每一个我们所定义的小程序被认为是类JApplet 的对象。此外，因为Japplet继承了Applet，每一个我们所定义的小程序同时也被认为是一个Applet 的对象。当开发applets时，这些信息是至关重要的，因为一个小程序容器只有当它是一个Applet才可以执行一个程序。虽然子类对象始终可以作为它的父类的一种来看待，父类对象却不被认为是其子类类型的对象。我们将利用这种“子类对象是父类对象”的关系来执行一些强大的操作。例如，绘图程序可以显示一系列图形，如果所有的图形类型都直接或间接地继
毕业设计外文资料翻译 （译文） 题目名称：Java and the Internet 学院：计算机科学技术 专业年级：计算机科学与技术（师）08 级 学生姓名：aaa 班级学号：a班a号 指导教师：aaa
二○一一年五月十三日 译文题目：Java和因特网 原文题目：Java and the Internet 原文出处：https://www.doczj.com/doc/d715389660.html,/view.html
Java and the Internet If Java is, in fact, yet another computer programming language, you may question why it is so important and why it is being promoted as a revolutionary step in computer programming. The answer isn’t immediately obvious if you’re coming from a traditional programming perspective. Although Java is very useful for solving traditional stand-alone programming problems, it is also important because it will solve programming problems on the World Wide Web. 1.Client-side programming The Web’s initial server-browser design provided for interactive content, but the interactivity was completely provided by the server. The server produced static pages for the client browser, which would simply interpret and display them. Basic HTML contains simple mechanisms for data gathering: text-entry boxes, check boxes, radio boxes, lists and drop-down lists, as well as a button that can only be programmed to reset the data on the form or “submit” the data on the form back to the server. This submission passes through the Common Gateway Interface (CGI) provided on all Web servers. The text within the submission tells CGI what to do with it. The most common action is to run a program located on the server in a directory that’s typically called “cgi-bin.” (If you watch the address window at the top of your browser when you push a button on a Web page, you can so metimes see “cgi-bin” within all the gobbledygook there.) These programs can be written in most languages. Perl is a common choice because it is designed for text manipulation and is interpreted, so it can be installed on any server regardless of processor or operating system. Many powerful Web sites today are built strictly on CGI, and you can in fact do nearly anything with it. However, Web sites built on CGI programs can rapidly become overly complicated to maintain, and there is also the problem of response time. The response of a CGI program depends on how much data must be sent, as well as the load on both the server and the Internet. (On top of this, starting a CGI program tends to be slow.) The initial designers of the Web did not foresee how rapidly this bandwidth would be exhausted for the kinds of applications people developed. For example, any sort of dynamic graphing is nearly impossible to perform with consistency because a GIF file must be created and moved from the server to the client for eac h version of the graph. And you’ve no doubt had direct experience with something as simple as validating the data on an input form. You press the submit button on a page; the data is shipped back to the server; the server starts a CGI program that discovers an error, formats an HTML page informing you of the error, and then sends the page back to you; you must then back up a page and try again. Not only is this slow, it’s inelegant. The solution is client-side programming. Most machines that run Web browsers are powerful engines capable of doing vast work, and with the original static HTML
xxxx大学高新学院毕业设计（论文） 外文翻译 学生姓名： 院（系）： 专业班级： 指导教师： 完成日期：
JSP基础学习资料 一、JSP 技术概述 在Sun 正式发布JSP(JavaServer Pages) 之后，这种新的Web 应用开发技术很快引起了人们的关注。JSP 为创建高度动态的Web 应用提供了一个独特的开发环境。按照Sun 的说法，JSP 能够适应市场上包括Apache WebServer 、IIS4.0 在内的85% 的服务器产品。即使您对ASP “一往情深”，我们认为，关注JSP 的发展仍旧很有必要。 ㈠JSP 与ASP 的简单比较 JSP 与Microsoft 的ASP 技术非常相似。两者都提供在HTML 代码中混合某种程序代码、由语言引擎解释执行程序代码的能力。在ASP 或JSP 环境下，HTML 代码主要负责描述信息的显示样式，而程序代码则用来描述处理逻辑。普通的HTML 页面只依赖于Web 服务器，而ASP 和JSP 页面需要附加的语言引擎分析和执行程序代码。程序代码的执行结果被重新嵌入到HTML 代码中，然后一起发送给浏览器。ASP 和JSP 都是面向Web 服务器的技术，客户端浏览器不需要任何附加的软件支持。 ASP 的编程语言是VBScript 之类的脚本语言，JSP 使用的是Java ，这是两者最明显的区别。此外，ASP 与JSP 还有一个更为本质的区别：两种语言引擎用完全不同的方式处理页面中嵌入的程序代码。在ASP 下，VBScript 代码被ASP 引擎解释执行；在JSP 下，代码被编译成Servlet 并由Java 虚拟机执行，这种编译操作仅在对JSP 页面的第一次请求时发生。 ㈡运行环境 Sun 公司的JSP 主页在https://www.doczj.com/doc/d715389660.html,/products/jsp/index.html ，从这里还可以下载JSP 规范，这些规范定义了供应商在创建JSP 引擎时所必须遵从的一些规则。 执行JSP 代码需要在服务器上安装JSP 引擎。此处我们使用的是Sun 的JavaServer Web Development Kit （JSWDK ）。为便于学习，这个软件包提供了大量可供修改的示例。安装JSWDK 之后，只需执行startserver 命令即可启动服务器。在默认配置下服务器在端口8080 监听，使用http://localhost:8080 即可打开缺省页面。 在运行JSP 示例页面之前，请注意一下安装JSWDK 的目录，特别是“ work ”子目录下的内容。执行示例页面时，可以在这里看到JSP 页面如何被转换成Java 源文件，然后又被编译成class 文件（即Servlet ）。JSWDK 软件包中的示例页