java论文外文文献及译文 第4页
description can be read out, Struts2 architecture and architecture Struts1 very different, Struts1 is to use the ActionServlet as its central processor, Struts2 is using an interceptor (FilterDispatcher) as its central processor, so One benefit is to make Action class and Servlet API was isolated.
Struts2 simple process flow is as follows:
1) browser sends a request
2) the processor to find the corresponding file under struts.xml the Action class to process the request
3) WebWork interceptor chain applications automatically request common functions, such as: WorkFlow, Validation functions
4) If Struts.xml Method configuration file parameters, then call the corresponding Action Method parameters in the Method class method, or call the Execute method to deal with common user request
5) Action class method returns the results of the corresponding response to the browser
Struts2 and Struts1 contrast:
1) Action class impleme优-文^论'文.网
http://www.youerw.com achieve the time to achieve any classes and interfaces, while providing a ActionSupport class Struts2, however, not required.
2) Struts1 the Action class is the singleton pattern, must be designed into the thread-safe, Struts2 was generated for each request for an instance
3) Struts1 the Action class dependence and the Servlet API, execute the method from its signature can be seen, execute method has two parameters Servlet HttpServletRequest and HttpServletResponse, Struts2 is not dependent on the Servlet API
4) Struts1 depends on the Servlet API the Web elements, therefore, of Action Struts1 when testing is difficult, it needs with other testing tools, Struts2 in Action can be as testing a number of other classes as Service Model layer test
5) Struts1 of Action and the View through the ActionForm or its sub-class of data transmission, although there LazyValidationForm this ActionForm appearance, but still can not like the other levels as a simple POJO data transfer, and Struts2 would like expect change becomes a reality
6) Struts1 binding of the JSTL, the preparation of convenience for the page, Struts2 integrates ONGL, you can use JSTL, Therefore, Struts2 is more powerful expression language under
Compared with Struts2 WebWork: Struts2 actually WebWork2.3, however, Struts2 WebWork, or with a little difference:
1) Struts2 IOC no longer support the built-in containers, use Spring's IOC container
2) Struts2 Ajax for Webwork features some of the label to use Dojo to be replaced
Servlet
Servlet is a server-side Java application, platform and protocol independent features that can generate dynamic Web pages. Customer requests to play it (Web browser or other HTTP client) and server response (HTTP server, database or application) of the middle layer. Servlet Web server is located inside the server-side Java applications started from the command line with the traditional application of different Java, Servlet loaded by the Web server, the Web server must include the Java Virtual Machine to support Servlet.
HTTP Servlet using a HTML form to send and receive data. To create an HTTP Servlet, need to extend the HttpServlet class, the class is a special way to handle HTML forms GenericServlet a subclass. HTML form is <FORM> and </ FORM> tag definition. Form typically includes input fields (such as text input fields, check boxes, radio buttons and selection lists) and a button for submitting data. When submitting information, they also specify which server should implement the Servlet (or other program). HttpServlet class contains the init (), destroy (), service () and other methods. Where init () and destroy () method is inherited.
init () method: In the Servlet life period, only run once init () method. It is executed when the server load Servlet. You can configure the server to start the server or the client's first visit to Servlet fashion into the Servlet. No matter how many clients to a优-文^论'文.网http://www.youerw.com ccess Servlet, will not repeat the init (). The default init () method is usually to meet the requirements, but can also use custom init () method to overwrite it, typically the management server-side resources. For example, you may write a custom init () to be used only once a load GIF images, GIF images and improve the Servlet returns with the performance of multiple clients request. Another example is to initialize the database connection. The default init () method sets the Servlet initialization parameters, and use it's ServletConfig object parameter to start the configuration, all
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