【正文】 g. Instead, these technologies take a pure markup language page as input, and generate Java methods. This essentially is changing the program flow。 certainly it isn39。t have to perform pointer addition in C or that no good programmer would ever insert code scriptlets, we all know what happens in practice. The Java language is a better language because it mandates that these sorts of bad habits never surface. But JSP in this case is much like C, allowing some very bad additional litmus test of the JSP technology39。 % TR BGCOLOR=FFCCCC TH width=50% ALIGN=center %=()% /TH TH width=50% ALIGN=center %=()% /TH /TR % } % /TABLE /CENTER /BODY /HTML JSP advocates are quick to let you know that JSP tag libraries can help you avoid this problem. Tag libraries allow custom tags (for example, AUTHORS /) to be added to a JSP page, which at runtime are resolved into code fragments in, well, tag use of a custom tag and associated tag library would allow the example 東華理工大學(xué)畢業(yè)設(shè)計(jì) 外文翻譯 12 above to be converted to that shown in Listing 6. class=displaycodeCENTER TABLE width=50% CELLPADDING=3 CELLSPACING=3 border=1 BGCOLOR=FFFFCC ACTORS / /TABLE /CENTER At runtime, the code for this tag executes and the correct results are inserted into the page. But this does not solve the problem. The argument against JSP technology is not whether content and presentation can be separated, but whether they must be separated. As long as JSP coding allows inline coding, it is very convenient (especially when deadlines are looming) to make lastminute changes with inline code, rather than converting the code to a tag library. If this doesn39。 } for (Iterator i = ()。s permissions, perform search differently (business logic!) Vector actors = () if (().hasPermission(ADMINISTRATOR)) { actors = (())。s the time to determine whether or not JSP actually acplishes this goal. As I39。ve e back to the idea of separating content from presentation. You39。m more than a bit dubious.)Still, choosing JSP technology forces you to use the Java language, at least for presentation and content. While CORBA can be used for business logic, JSP coding does necessitate some familiarity with servlets as well as the core Java language. Since many developers e to JSP coding through the J2EE platform, this doesn39。t be given too much weight. Java technology for enterprise applications (in 東華理工大學(xué)畢業(yè)設(shè)計(jì) 外文翻譯 10 my opinion, at least) is the only language choice. And there are no languageindependent solutions in this space anyway. Of course, at this stage of the game, I39。t have to use it! Take a close look at both the positives and the negatives before choosing to use JSP technology in your applications. Let39。t use these APIs, their applications somehow won39。m ready to cut to the chase: JSP technology, while built on good ideas, presents quite a few problems. Before you choose to use JSP coding in your applications (which you might still do), you should at least be aware of possible should also be aware of a facet of the J2EE programming platform that is often ignored: just because an API es with the platform doesn39。m not editorializing yet. Designer vs. developer A final (and admirable) goal of JSP technology worth mentioning is that it seeks to establish clearly defined roles in the application development process. By ostensibly breaking content from presentation, JSP technology creates a clearer distinction between the designer and developer. The designer creates markup, using only standard HTML, WML, or whatever language is appropriate, and the developer writes code. Of course, many designers today have learned JavaScript, so it should e as no surprise that many of these same designers have begun to learn JSP coding. Often, instead of just doing pure markup, they encode a plete JSP page and hand it over to the developer. Then the usual tweaking takes place, and the developer puts the JSP page into place as a frontend for some portion of the overall application. The key, though, is that many designers do not learn JSP coding, so it must also be workable in that environment. The problemsI39。 I39。 ()) { Actor actor = (Actor)()。s petition from Microsoft was at an alltime high, primarily due to the success of Microsoft Active Server Pages (ASP). The similarity of the name JavaServer Pages to Active Server Pages was not merely coincidental. And the ability to mimic many of ASP39。 into their servlet code. This mixing of hardcoded content with runtime variables presented a horrible burden on servlet developers. It also made making even minor changes to the presentation layer difficult for the technology addresses this situation by allowing normal HTML pages (and later, WML or other markup language pages) to be piled at runtime into a Java servlet, essentially mimicking the () paradigm, without requiring the developer to write this code. And it allows you to insert variables into the page that are not interpreted until a JSP page the HTML snippet shown in Listing 2 could look like the example in Listing 3. class=displaycode% page import= % 東華理工大學(xué)畢業(yè)設(shè)計(jì) 外文翻譯 7 % page import= % % PageInfo pageInfo = (PageInfo)(PAGE_DATA) % HTML HEAD TITLE %=()% /TITLE /HEAD BODY ! Other HTML content /BODY /HTML Judging by these initial principles, then, JSP technology (at least in its stated design) would satisfy the first te of a presentation technology, as outlined above: that content be separat