【導(dǎo)讀】1994年，當(dāng)時(shí)主流的采用Web應(yīng)用程序的開發(fā)才剛開始。不成熟，只有較少的工具能幫助開發(fā)人員構(gòu)建Web軟件。結(jié)果，在特定解決方。案中的應(yīng)用程序混合了HTML代碼與應(yīng)用程序邏輯。很顯然，UI設(shè)計(jì)的更改。這兩種元素?cái)嚭驮谝黄?，進(jìn)而導(dǎo)致錯(cuò)誤和緩慢的進(jìn)展。工作關(guān)系，這常常會(huì)造成時(shí)間上的浪費(fèi)。UI設(shè)計(jì)人員能夠?qū)︼@示進(jìn)行卓有成效的工作，同時(shí)開發(fā)人員能夠?qū)Ｗ⒂谶?。然而，這種方法仍存在一些缺陷。顯示表單；等待用戶填寫然后提交數(shù)據(jù)。檢查各個(gè)域值是否有效；如果有錯(cuò)誤，則重新顯示表單。處理用戶輸入的數(shù)據(jù)，可能將其存儲(chǔ)在一個(gè)數(shù)據(jù)庫中。Struts，一種開放源碼“模。它以與交付產(chǎn)品一起分發(fā)的形式受到來自。目前的Struts發(fā)行版本是，但自2020年3月19日起有一個(gè)標(biāo)。市，而在Struts郵件列表上已經(jīng)有這種呼聲。因此，任何利用Struts的新項(xiàng)目。的添加可能是將Tiles模板庫合并到Struts分發(fā)版中。程序沒有利用Struts和Tiles；它演示了以頁面為中心的方法。啟動(dòng)并正確運(yùn)行。缺省情況下，Tomcat附帶了Examples應(yīng)用程序。

　　

【正文】 =x extends=y/ tag is where the magic that delivers agility to user interface development happens. By specifying a master layout and extending it, you have the flexibility of not only changing mon elements like topBanner, topMenu, panel1, panel2, and other ponents, but also the freedom to put different elements on the page and change where they are located. For instance, you could add panel4, a tile to display the local weather, below panel2 on the left side of the page. As long as the weather code does not require any input from the user or interaction with other ponents on the page, you could make the addition of panel4 without any changes whatsoever to the application business logic, or even any changes to JSP pages other than . 7 More plex uses of Struts and Tiles Space does not permit me to discuss other useful aspects of the Struts and Tiles package in depth, but I do want to touch on them briefly so you can get a sense of what Struts and Tiles can do. Perhaps these can be the topics of future articles if there is sufficient demand. You will note that in both the examples in this article, I coded some basic validation of the first name, last name, favorite color, and birthdate. Simple validation of the sort I employed could actually be performed by Struts using its format validation, thus saving time spent coding Java statements. It is possible, for instance, to check for empty strings, to check that a string matches a date, or to check for a match with some other regular expression. You will find it very handy to use format validation as a firstlevel check with which your program can eliminate obvious errors before checking for adherence to more plex business logic rules. Struts provides a validator package that is configured via a descriptor in the WEBINF directory. I have not included the validator package in the two examples。 if you would like to try it out, it39。s included with the Struts bundle. Another useful feature of the Struts and Tiles package is integration with containermanaged security. Many of you are using application servers such as IBM WebSphere or JBoss. These servers facilitate authentication and authorization by handling many of the routine tasks involved in security, freeing you from having to code them. Struts allows you to conditionally display different bits of bean data to different users based on user role, which is determined by automatically querying the container. Similarly, the Tiles framework allows you to conditionally display different view ponents to different users based on user role, again determined by automatically querying the container. I use these features in my own applications to display different menus to administrators, regular users, or guests. Finally, I have not touched on internationalization in my examples, but it is a real concern for people building large applications that will ultimately be published in multiple languages. Struts lets you create message resource properties files that specify text for labels, titles, and other output. If you have populated a message resource properties file with all outputs in several different languages, you can change all widgets and hardcoded text to the appropriate language with a simple change of the language setting, even on the fly. Future directions Where do Struts and Tiles go from here? Two changes on the horizon promise to 8 make Struts and Tiles even more useful. The first is a workflow management system. You have likely dealt with many multistep business processes。 coding them in a Web application today can be a major pain because you have to coordinate the different steps, each of which is a separate method within a Java class or a separate servlet or JSP page. Tools in the mercial marketplace help with managing multistep business processes by enabling developers to model them, then automatically generating Java code that serves as scaffolding. The Struts workflow management system will provide similar functionality, allowing developers to script business processes that span multiple pages in a Web application and specify how the pages interact through a central, rulesbased system. The other, equally promising uping change is the incorporation of Struts tags in the JSP Standard Tag Library, a Jakarta project that seeks to produce a collection of useful custom tags that simplify and speed development of Web applications written with JSP pages. What this means is that Web applications will be easier than ever to develop because you will have a prewritten library of code to draw upon using the standard mechanism of custom tags. Also, the project39。s incorporation within the JSP STL standard ensures even wider distribution and availability of the Struts and Tiles functionality, meaning portability of skills for developers moving between projects and easy access to skilled talent for panies looking to develop Web applications. What can you take away from this article?After reading this article, the following key points should stay with you: MVC is a good architecture for developing robust Web software. A pageoriented architecture is simple, but fails as an application grows in size and scope. MVC is a proven model for larger applications. Struts and Tiles provide a solid base for plex applications. Struts and Tiles adhere to the MVC paradigm and allow developers to create an application that can manageably grow with the needs of the business. Struts and Tiles enjoy strong industry support, as well as popularity and momentum among developers. This ensures broad adoption and protects the investment of time and money made by developers and panies. With Struts and Tiles, you39。ll find it easier to unleash your own Web applications on the world