12.11.08 1 Basic Struts Architecture Client Server Database Request Response Control View Model...

12.11.08 1

Basic Struts Architecture

Client ServerDatabase

Request

Response

Control

View

Model

Server

Struts Framework

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Struts 2 flow (a bird eye view)

source: www.coreservlets.com; Jakarta Struts: Processing Requests with Action Objects Struts 1.2 Version

Request …/blah.action

Struts.xml

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Struts 2 Lifecycle

Source: http://static.raibledesigns.com/repository/presentations/MigratingFromStruts1ToStruts2.pdf

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Struts 2 – Behind the scenes

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Struts 2 – Behind the scenes (Cont…)HttpServletRequest – Request goes to servlet container

Filters - various filters are applied

FilterDispatcher – required filter dispacher is called

ActionMapper –dispatcher consults mapper to invoke action or not

ActionProxy – control is passed to proxy and it consults configuration manager for appropriate action and settings and then creates invocation

ActionInvocation – calls interceptors before calling the Action

Interceptors – interceptors do preActions

ActionExecution – Action method is called

ResultsPreparation – result is rendered depending upon the action method response

Interceptors – interceptors are called in reverse order for postActions

Filters – response is passed through filters

HttpServletResponse – response is given to client

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Hello World!

One time configuration Web.xml

Three steps process Create view (JSP) Create Action Class Map Action and view

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Web.xml

Placed in WEB-INF folder

<?xml version="1.0" encoding="UTF-8"?>

<web-app id="WebApp_9" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<display-name>Struts Example</display-name>

<filter>

<filter-name>defaultDispatcher</filter-name>

<filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>

</filter>

<filter-mapping>

<filter-name>defaultDispatcher</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

</web-app>

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Welcome.jsp

<%@ page contentType="text/html; charset=UTF-8" %> <%@ taglib prefix="s" uri="/struts-tags" %> <html> <head> <title>Welcome</title> </head>

<body> <s:property value="message"/> </body> </html>

Creating Welcome Page

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Welcome.java package example; import com.opensymphony.xwork2.ActionSupport;

public class Welcome extends ActionSupport{

private String message = "default String";

public String getMessage() { return message;

}

public void setMessage(String message) { this.message = message;

}

public String execute() throws Exception { message = “Hello World! My First App is running"; return SUCCESS; // String SUCCESS = “success”

} }


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Welcome.java Either implement ActionSupport Or extend Action Or neither

Do provide execute method Framework will search for execute method through Reflection

Default execute method returns SUCCESS Execute is the default entry point for Action class Some return strings constants are already provided

SUCCESS=“success” INPUT=“input” NONE=“none” ERROR=“error” LOGIN=“login”

SUCCESS is the default return string Also returned by default execute method

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Struts.xml

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration

2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

<constant name="struts.enable.DynamicMethodInvocation" value=“false" />

<constant name="struts.devMode" value="false" /><include name=“someFile.xml” />

<package name="StrutsExample" extends="struts-default"> <action name="Welcome" class="example.Welcome"> <result>/jsp/welcome.jsp</result> </action> </package>

</struts>

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<s:property value="message"/>

welcome.jsp Welcome.javaprivate String message =

"default String";public String getMessage() {return message;}public void setMessage

(String message) {this.message = message;}

<action name="Welcome" class="example.Welcome">

url= http://localhost:8081/struts2/Welcome.action

Welcome Page

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Behind the scenes

Source: http://struts.apache.org/2.x/docs/big-picture.html

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Struts 2 features

Struts Tag Library Wildcard mappings Validation Localization OGNL expression language Interceptors Dynamic Method Invocation Profiling Debugging Annotations Type Conversion Result Types Dependency Injection Development Mode

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Struts Tag Library

<%@ page contentType="text/html; charset=UTF-8" %><%@ taglib prefix="s" uri="/struts-tags" %><html><head> <title>Welcome</title></head>

<body><s:form action="Login"><s:property value="errorMessage"/><s:textfield name="username" label="User Name"/><s:password name="password" label="Password" /><s:submit></s:submit></s:form></body></html>

Creating Login PageLogin.jsp

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Struts Tag Librarypackage example;import com.opensymphony.xwork2.*;

public class Login extends ActionSupport {private String username = "default";private String password = "";private String errorMessage = "";

public String getUsername() { return username; }public void setUsername (String username) { this.username = username;}public String getPassword () { return password;}public String getErrorMessage () { return errorMessage; }public void setErrorMessage (String errorMessage) {this.errorMessage =

errorMessage;}public void setPassword (String password) {this.password = password;}

public String execute () throws Exception {if (isValid(getUsername()) && isValid(getPassword())){ return

SUCCESS; }errorMessage = "invalid input";return "inputError";}

public boolean isValid(String field){return field.length()!=0?true:false;

}}

Creating Login PageLogin.java

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Struts Tag Library<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>

<constant name="struts.enable.DynamicMethodInvocation" value=“false" /> <constant name="struts.devMode" value="false" />

<action name="Login" class="example.Login"> <result>/jsp/success.jsp</result> <result name="inputError">/jsp/login.jsp</result></action>

<package name="StrutsExample" extends="struts-default"> <action name="Welcome" class="example.Welcome"> <result>/jsp/welcome.jsp</result> </action> </package>

</struts>

Creating Welcome PageStruts.xml

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Struts Tag Library

<%@ page contentType="text/html; charset=UTF-8" %><%@ taglib prefix="s" uri="/struts-tags" %><html><head> <title>Welcome</title></head>

<body>

s:property value="message"/><a href="<s:url action="Login"/>">Login</a>

<s:url id=“someID" action="Welcome"><s:param name="param1">value1</s:param>

</s:url><s:a href=“%{someID}">Welcome</s:a></body></html>

Adding links for Login Pagewelcome.jsp

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Wildcard mappings

Provides generic mappings GuestLogin and PremierLogin can both be mapped to *Login

Calls EditUser & EditRegistration for /editUser & /editRegistration respectively

Returns /jsp/User.jsp & /jsp/Registration.jsp respectively

<action name="edit*" class="example.Edit{1}">

<result name="failure" path="/mainMenu.jsp"/>

<result path="/jsp/{1}.jsp"/>

</action>

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Validation

Define configuration file *-validation.xml or use annotations className-validation.xml

Place in the directory where .class file is placed example.Login should have Login-validation.xml

<!DOCTYPE validators PUBLIC "-//OpenSymphony Group//XWork Validator 1.0.2//EN" "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd"><validators> <field name="username"> <field-validator type="requiredstring"> <message>Username is required</message> </field-validator> </field> <field name="password"> <field-validator type="requiredstring"> <message>Password is required</message> </field-validator> </field></validators>

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Localization

Get message from resource bundles Generalizes the messages Reusable messages Create <classname>.properties file for specific class and place in

the class path Create package.properties file for specific package Searches for properties file in order

ActionClass.properties BaseClass.properties Interface.properties (every interface and sub-interface) ModelDriven's model (if implements ModelDriven), for the model object

repeat from 1 package.properties (of the directory where class is located and every parent

directory all the way to the root directory) search up the i18n message key hierarchy itself global resource properties

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Localization

user.required=User Name is required password.required=Password is required

Login.properties

<validators> <field name="username"> <field-validator type="requiredstring"> <message key="username.required"/> </field-validator> </field> <field name="password"> <field-validator type="requiredstring"> <message key="password.required"/> </field-validator> </field></validators>

Login-validation.xml

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Localization cont…

Use either of <s:property value="getText('some.key')" />

for accessing properties from JSP or Java file <s:text name="some.key" /> <s:text name="some.invalid.key" > The Default Message

That Will Be Displayed </s:text>

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Interceptors

Can execute code before and after execution Are thread-safe Can be used for

Validation Pre populating fields Double-submit prevention Session control Authentication Type conversion

12.11.08 1 Basic Struts Architecture Client Server Database Request Response Control View Model...

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