1 / 34

Struts

Struts. A JSP Web Application Framework. What is Struts?. A JSP Web Application Framework Provided by the Apache Software Foundation Exploits MVC architecture (Model 2). Why do we need Struts?.

mlahr
Download Presentation

Struts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Struts A JSP Web Application Framework

  2. What is Struts? • A JSP Web Application Framework • Provided by the Apache Software Foundation • Exploits MVC architecture (Model 2)

  3. Why do we need Struts? • Struts combines Java Servlets, Java ServerPages, custom tags, and message resources into a unified framework • Cooperative, synergistic platform, suitable for development teams, independent developers

  4. MVC Architecture Layer Architecture: • M – Model (Java Beans) • V – View (JSPs) • C – Controller (Servlet) Appropriate for web applications that are: • Complex and large in size • Containing a lot of dynamic contents

  5. MVC – How does it work? Event (request) Client (Web Browser) Controller (servlet) Event (forward) Data (response) Event (dispatch) Data Storage (Database, Files,etc.) View (JSPs) Model (Beans) Data Data (beans properties)

  6. MVC - Motivators • Isolate presentation logic from business logic • Make business logic independent from specific protocol (e.g. HTTP, XML, RMI)

  7. Web Application Framework • Help developers build Web applications • Applications share common set of functionality • Provide classes and interfaces that can be used/extended by developers

  8. The Struts Framework • Pre-implemented framework based on MVC architecture • Delegated to Web tier • Consists of • Components (Java classes) that implement back-bone mechanism of Struts • Extensive Custom Tag libraries

  9. Struts Components Business API (Business logic) ActionServlet (Controller) dispatch Action (Controller) data request Client (Web Browser) populate properties data forward Data Strage (Database, Files, etc.) dynamic contents JSPs (View) ActionForm (Model) Bean (Model) response ActionMapping ActionForward ActionErrors ActionError Tab Libraries And more…

  10. Struts Basic Process Web Browser sends a request (called action) to the servlet controller (ActionServlet) • mapping information of • Action instance • ActionForm instance • with its scope • etc. Web Browser ActionServlet ActionMapping request get forward get or create get or create return the control response pass the control data JSP ActionForm Action Business Logic data data data The servlet controller copies parameters in the request into the mapped ActionForm instance, then invokes validate() method. The servlet controller retrieves an appropriate instance of ActionMapping according to the action The servlet controller forwards the request to the specified page. The servlet controller gets the reference of mapped ActionForm instance, or creates the instance if not existed, then invokes reset() method. The Action instance processes data by accessing business logic. The servlet controller invokes execute() method of the Action instance. The JSP retrieves data from the mapped ActionForm instance and sends response back to the Web Browser. The Action instance returns forwarding page information (ActionForward instance). The servlet controller gets the reference of mapped Action instance, or creates the instance if not existed.

  11. Provided functionalities (1) • Message resource bundle and Internationalization (I18N) • Respond in appropriate language according to the property of Web browser that sent the request • Input validator • Efficient mechanism to validate user input • Error Handling • You can generate error messages and pass them to the appropriate page with simple mechanism

  12. Provided functionalities (2) • Tiles • Template (or layout) approach provided by Tiles Tag library for JSP development • Advanced Access for Bean Properties • With Bean Tag Library, you can access not only simple properties of Beans, but also nested properties and/or indexed properties • Plugin • Load and configure application-specific class as the web application is starting up • And more…

  13. How to use Struts • Prerequisite Software • Installation • Configuration • Development • Deployment

  14. How to use - Prerequisite • JDK (J2SE 1.4.2 suggested) • XML Parser Required (Bundled with J2SE 1.4 or later) • Servlet Container with servlet.jar • DBMS with JDBC (Optional) • Ant Build System 1.5.4 or later (Optional) • If you build Struts from the source distribution

  15. How to use – Installation (1) • Download the binary distribution or the source code distribution from http://struts.apache.org/acquiring.html • Unzip (and build) the distribution • Create your web application root folder ,appropriate subfolders, two configuration files (web.xml and struts-config.xml), and a message resource properties file (MessageResource.properties) • Copy required files from the distribution to your web application

  16. How to use – Installation (2) jakarta-struts-1.1 (webapp_root) *.jsp, *.html, etc. lib WEB-INF *.jar *.tld web.xml struts-config.xml webapps *.tld *.war lib *.jar Copy to webapps folder Of the servlet container classes MessageResourse.properties *.class

  17. How to use – Configuration (1) • web.xml • servlet element • servlet mapping element • taglib elements <?xmlversion="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd"> <web-app> <display-name>Your webapp name</display-name> <!-- add elements here --> </web-app>

  18. How to use – Configuration (2) • servlet element <servlet> <servlet-name>action</servlet-name> <servlet-class> org.apache.struts.action.ActionServlet </servlet-class> <init-param> <param-name>config</param-name> <param-value> /WEB-INF/struts-config.xml </param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet>

  19. How to use – Configuration (3) • servlet mapping element <servlet-mapping> <servlet-name>action</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping>

  20. How to use – Configuration (4) • taglib elements <taglib> <taglib-uri> http://struts.apache.org/tags-bean </taglib-uri> <taglib-location> /WEB-INF/struts-bean.tld </taglib-location> </taglib> … <taglib> <taglib-uri> http://struts.apache.org/tags-nested </taglib-uri> <taglib-location> /WEB-INF/struts-nested.tld </taglib-location> </taglib>

  21. How to use – Configuration (5) • struts-config.xml • form-beans element • grobal-forwards element • action-mappings element • message-resources element <?xmlversion="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd"> <struts-config> <!-- add elements here --> </struts-config>

  22. How to use – Configuration (6) • form-beans element <form-beans> <form-beanname=“registrationForm” type=“RegistrationFrom” /> <form-beanname=“loginForm” type=“LoginForm” /> … <form-beanname=“orderForm” type=“OrderForm” /> </form-beans>

  23. How to use – Configuration (7) • global-forwards element <global-forwards> <forwardname=“home” path=“/index.jsp” /> <forwardname=“login” path=“/login.jsp” /> <forwardname=“main” path=“/main.jsp” /> … <forwardname=“error” path=“/error.jsp” /> </global-forwards>

  24. How to use – Configuration (8) • action-mappings element <action-mappings> <actionpath=“/login” type=“LoginAction” name=“loginForm” scope=“request” input=“/login.jsp”> </action> … <actionpath=“/logout” type=“LogoutAction” > </action> </action-mappings>

  25. How to use – Configuration (9) • message-resourses element <message-resourcesparameter=“MessageResources” />

  26. How to use – Configuration(10) • MessageResource.properties #format: <key>=<value> #errors errors.header=<hr />The following errors occur: <ul> errors.footer=</ul><hr /> errors.prefix=<li> errors.suffix=</li> error.input.required={0} is required. error.user.invalid=Invalid username or password. …

  27. How to use – Development • Create JSPs • Create subclasses of ActionForm class • i.e. LoginForm.class • Should be created for each form • Create subclasses of Action class • i.e. LoginAction.class • Must be thread-safe • Create other classes in business logic • i.e. StateBean classes

  28. How to use – Develoyment • Copy your web application root folder under webapps folder of your servlet container • Restart the servlet container to reload your web application • Access to http://hostname/webapp_root from your web browser

  29. Development Example (1) • login.jsp <%@ taglib uri=“http://struts.apache.org/tags-html” prefix=“html” %> <html> <head><title>Login</title></head> <body> <h3>Log In</h3> <html:errors /> <html:form action=“/login.do” focus=“username”> Username: <html:text property=“username” /><br /> Password: <html:password property=“password” redisplay="false"/><br /> <html:submit>submit</html:submit> </html:form> </body> </html>

  30. Development Example (2) • LoginForm.java import org.apache.struts.action.*; import javax.servlet.http.HttpServletRequest; public class LoginForm extends ActionForm { private String username = null; private String password = null; public String getUsername() { return username; } public String getPassword() { return password; } public void setUsername(String username) { this.username = username; } public void setPassword(String password) { this.password = password; } public void reset(ActionMapping mapping, HttpServletRequest request) { username = null; password = null; }

  31. Development Example (3) • LoginForm.java (continued) public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) { ActionErrors errors = new ActionErrors(); if(username==null || username.length()==0) { ActionError error = new ActionError(“error.input.required”, “Username”); errors.add(ActionErrors.GLOBAL_ERROR, error); } if(password==null) || password.length()==0) { ActionError error = new ActionError(“error.input.required”, “Password”); errors.add(ActionErrors.GLOBAL_ERROR, error); } return errors; } }

  32. Development Example (4) • LoginAction.java import org.apache.struts.action.*; import javax.servlet.http.*; import your_package.business.Service; public class LoginAction extends Action { public ActionForward execute (ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) { String username = ((LoginForm)form).getUsername(); String password = ((LoginForm)form).getPassword();

  33. Development Example (5) • LoginAction.java (continued) if(!Service.authenticate(username, password)) { errors.add(ActionErrors.GLOBAL_ERROR, new ActionError(“error.user.invalid”)); saveErrors(request, errors); return mapping.getInputForward(); } else { request.getSession().setAttribute(“loginUser”, username); return mapping.findForward(“main”); } } }

  34. Tips for Good Design • Separate your business logic from Struts components • Allow only downward dependency Struts components can call Business Logic but Business Logic cannot call Struts component or Servlet classes • Call business logic through Interface Provide well-designed interface to be able to change implementation in business logic without change in web tier Struts components (Web tier) Interface Business Logic (Business tier)

More Related