【文章內(nèi)容簡(jiǎn)介】 y reinvent the wheel, or a tag library? If you cannot find something you need in the library, contribute. In addition, Struts provides a starting point if you are learning JSP tag technology. ? Open source You have all the advantages of open source, such as being able to see the code and having everyone else using the library reviewing the code. Many eyes make for great code review. ? Sample MVC implementation Struts offers some insight if you want to create your own MVC implementation. ? Manage the problem space Divide and conquer is a nice way of solving the problem and making the problem manageable. Of course, the sword cuts both ways. The problem is more plex and needs more management. b)Struts cons ? Youth Struts development is still in preliminary form. They are working toward releasing a version , but as with any version, it does not provide all the bells and whistles. ? Change The framework is undergoing a rapid amount of change. A great deal of change has occurred between Struts and . You may want to download the most current Struts nightly distributions, to avoid deprecated methods. In the last 6 months, I have seen the Struts library grow from 90K to over 270K. I had to modify my examples several times because of changes in Struts, and I am not going to guarantee my examples will work with the version of Struts you download. ? Correct level of abstraction Does Struts provide the correct level of abstraction? What is the proper level of abstraction for the page designer? That is the $64K question. Should we allow a page designer access to Java code in page development? Some frameworks like Velocity say no, and provide yet another language to learn for Web development. There is some validity to limiting Java code access in UI development. Most importantly, give a page designer a little bit of Java, and he will use a lot of Java. I saw this happen all the time in Microsoft ASP development. In ASP development, you were supposed to create COM objects and then write a little ASP script to glue it all together. Instead, the ASP developers would go crazy with ASP script. I would hear Why wait for a COM developer to create it when I can program it directly with VBScript? Struts helps limit the amount of Java code required in a JSP file via tag libraries. One such library is the Logic Tag, which manages conditional generation of output, but this does not prevent the UI developer from going nuts with Java code. Whatever type of framework you decide to use, you should understand the environment in which you are deploying and maintaining the framework. Of course, this task is easier said than done. ? Limited scope Struts is a Webbased MVC solution that is meant be implemented with HTML, JSP files, and servlets. ? J2EE application support Struts requires a servlet container that supports JSP and Servlet specifications. This alone will not solve all your install issues, unless you are using Tomcat . I have had a great deal of problems installing the library with Netscape iPla , which is supposedly the first J2EEpliant application server. I remend visiting the Struts User Mailing List archive (see Resources) when you run into problems. ? Complexity Separating the problem into parts introduces plexity. There is no question that some education will have to go on to understand Struts. With the constant changes occurring, this can be frustrating at times. Wele to the Web. ? Where is... I could point out other issues, for instance, where are the client side validations, adaptable workflow, and dynamic strategy pattern for the controller? However, at this point, it is too easy to be a critic, and some of the issues are insignificant, or are reasonable for a release. The way the Struts team goes at it, Struts might have these features by the time you read this article, or soon after. 6 Future of Struts Things change rapidly in this new age of software development. In less than 5 years, I have seen things go from cgi/perl, to ISAPI/NSAPI, to ASP with VB, and now Java and J2EE. Sun is working hard to adapt changes to the JSP/servlet architecture, just as they have in the past with the Java language and API. You can obtain drafts of the new JSP and Servlet specifications from the Sun Web site. Additionally, a standard tag library for JSP files is appearing. 外文翻譯 2 Struts—— MVC 的一種開(kāi)放源碼實(shí)現(xiàn) 摘要： 本文介紹 Struts，它是使用 servlet 和 JavaServer Pages 技術(shù)的一種 ModelViewController 實(shí)現(xiàn)。 Struts 可幫助您控制 Web 項(xiàng)目中的變化并提高專(zhuān)業(yè)化水平。盡管您可能永遠(yuǎn)不會(huì)用 Struts 實(shí)現(xiàn)一個(gè)系統(tǒng)，但您可以將其中的一些思想用于您以后的 servlet 和 JSP 網(wǎng)頁(yè)的實(shí)現(xiàn)中。 關(guān)鍵字： Struts； MVC； JSP 1 簡(jiǎn)介 學(xué)生也可以在因特網(wǎng)上發(fā)布 HTML 網(wǎng)頁(yè)。但是， 學(xué)生的網(wǎng)頁(yè)和專(zhuān)業(yè)開(kāi)發(fā)的網(wǎng)站有質(zhì)的區(qū)別。網(wǎng)頁(yè)設(shè)計(jì)人員（或者 HTML 開(kāi)發(fā)人員）必須理解顏色、用戶(hù)、生產(chǎn)流程、網(wǎng)頁(yè)布局、瀏覽器兼容性、圖像創(chuàng)建和 JavaScript 等等。設(shè)計(jì)漂亮的網(wǎng)站需要做大量的工作，大多數(shù) Java 開(kāi)發(fā)人員更注重創(chuàng)建優(yōu)美的對(duì)象接口，而不是用戶(hù)界面。 JavaServer Pages (JSP) 技術(shù)為網(wǎng)頁(yè)設(shè)計(jì)人員和 Java 開(kāi)發(fā)人員提供了一種聯(lián)系鈕帶。 如果您開(kāi)發(fā)過(guò)大型 Web 應(yīng)用程序，您就理解 變化 這個(gè)詞的含義。 ―模型 視圖 控制器 ‖(MVC) 就是用來(lái)幫助您控制變化的一種設(shè)計(jì)模式。 MVC 減弱了業(yè)務(wù)邏輯接口和數(shù)據(jù)接口之間的耦合。 Struts 是一種 MVC 實(shí)現(xiàn)，它將 Servlet 和 JSP 標(biāo)記（屬于 J2EE 規(guī)范）用作實(shí)現(xiàn)的一部分。盡管您可能永遠(yuǎn)不會(huì)用 Struts 實(shí)現(xiàn)一個(gè)系統(tǒng)，但了解一下 Struts 或許使您能將其中的一些思想用于您以后的 Servlet 的 JSP 實(shí)現(xiàn)中。 2 模型 視圖 控制器 (MVC) JSP 標(biāo)記只解決了部分問(wèn)題。我們還得處理驗(yàn)證、流程控制和更新應(yīng)用程序的狀態(tài) 等問(wèn)題。這正是 MVC 發(fā)揮作用的地方。 MVC 通過(guò)將問(wèn)題分為三個(gè)類(lèi)別來(lái)幫助解決單一模塊方法所遇到的某些問(wèn)題： ? Model（模型 ） ： 模型包含應(yīng)用程序的核心功能。模型封裝了應(yīng)用程序 的狀態(tài)。有時(shí)它包含的唯一功能就是狀態(tài)。它對(duì)視圖或控制器一無(wú)所知。 ? View（視圖） ： 視圖提供模型的表示。它是應(yīng)用程序的 外觀 。視圖可以訪問(wèn)模型的讀方法，但不能訪問(wèn)寫(xiě)方法。此外，它對(duì)控制器一無(wú)所知。當(dāng)更改模型時(shí)，視圖應(yīng)得到通知。 ? Controller（控制器） ： 控制器對(duì)用戶(hù)的輸入作出反應(yīng)。它創(chuàng)建并設(shè)置模型。 3 MVC Model 2 Web 向軟件開(kāi)發(fā)人員提出了一些特有的挑戰(zhàn)，最明顯的就是客戶(hù)機(jī)和服務(wù)器的無(wú)狀態(tài)連接。這種無(wú)狀態(tài)行為使得模型很難將更改通知視圖。在 Web 上，為了發(fā)現(xiàn)對(duì)應(yīng)用程序狀態(tài)的修改，瀏覽器必須重新查詢(xún)服務(wù)器。 另一個(gè)重大變化是實(shí)現(xiàn)視圖所用的技術(shù)與實(shí)現(xiàn)模型或控制器的技術(shù)不同。當(dāng)然，我們可以使用 Java（或者 PERL、 C/C++ 或別的語(yǔ)言）代碼生成 HTML。這種方法有幾個(gè)缺點(diǎn)： ? Java 程序員應(yīng)該開(kāi)發(fā)服務(wù)，而不是 HTML。 ? 更改布局時(shí)需要更改代碼。 ? 服務(wù)的用戶(hù)應(yīng)該能夠創(chuàng)建網(wǎng)頁(yè) 來(lái)滿(mǎn)足它們的特定需