Advanced Struts

8/14/2019 Advanced Struts

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Advanced Struts


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Sang Shin

[email protected]

Java Technology EvangelistSun Microsystems, Inc.


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Disclaimer & Acknowledgments

Even though Sang Shin is a full-time employee of SunMicrosystems, the content in this presentation is created as hisown personal endeavor and thus does not reflect any officialstance of Sun Microsystems.

Sun Microsystems is not responsible for any inaccuracies in thecontents.

Acknowledgments:

I borrowed from presentation slides from the following sources Using the Struts framework presentation material from Sue Spielman of

Switchback Software ([email protected]) Struts' user's guide is also used in creating slides and speaker notes

Source code examples are from Cookbook example originally written by

I also used Programming Jakarta Struts book written by Chuck Cavaness


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Revision History

12/01/2003: version 1: created by Sang Shin 04/09/2004: version 2: speaker notes are polished a bit Things to do

speaker notes need to be added more example codes need to be added

javascript slides need to be added


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Advanced Struts Topics

Extending & customizing Struts framework

Plug-In API (1.1)

DynaActionForm (1.1)

Validation framework (1.1)

Declarative exception handling (1.1)

Multiple application modules support (1.1)


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Advanced Struts Topics

Accessing database

Struts-EL tag library

Struts and security Struts utility classes Nested tag library

Differences between Struts 1.0 and 1.1 Roadmap


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Extending &Customizing

Struts Framework


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Extending Struts Framework

Struts framework is designed withextension and customization in mind It provides extension hooks

Validator and Tiles use these extension hooks

Extend the framework only ifdefaultsetting does not meet your needs

There is no guarantee on the backwardcompatibility in future version of Struts if you areusing the extension


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Extension/Customization

Mechanisms of the Framework Plug-in mechanism (1.1)

Extending framework classes (1.1) Extending Struts configuration classes

Extending ActionServlet class

Extending RequestProcessorclass

Extending Action class DispatchAction (1.1) Using multiple configuration files (1.1)


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Extension/Customization:Plug-in Mechanism


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What is a Plug-in?

Any Java class that you want to initializewhen Struts application starts up anddestroy when the application shuts down

Any Java class that implementsorg.apache.struts.action.Plugin interface

public interface PlugIn {

public void init(ActionServlet servlet,ApplicationConfig config)

throws ServletException;

public void destroy();

}


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Why Plug-in?

Before Struts 1.1 (in Struts 1.0), you had tosubclass ActionServlet to initializeapplication resources at startup time

With plugin mechanism (in Struts 1.1), youcreate Plugin classes and configure them

Generic mechanism

Struts framework itself uses plugin mechanism forsupporting Validator and Tiles


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How do you configure Plug-in's?

Must be declared in struts-config.xml via element

3 example plug-in's in struts-example sample

application


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How do Plug-in's get called?

During startup of a Struts application,ActionServlet calls init() method of eachPlug-in configured

Plug-ins are called in the order they areconfigured in struts-config.xml file


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init() of MemoryDatabasePlugin in

struts-example sample applicationpublic final classMemoryDatabasePlugIn implements PlugIn {

.../*** Initialize and load our initial database from persistent storage.*

* @param servlet The ActionServlet for this web application* @param config The ApplicationConfig for our owning module** @exception ServletException if we cannot configure ourselves correctly*/

public void init(ActionServlet servlet, ModuleConfig config)throws ServletException {

log.info("Initializing memory database plug in from '" +pathname + "'");

// Remember our associated configuration and servletthis.config = config;this.servlet = servlet;


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Continued... // Construct a new database and make it available

database = new MemoryUserDatabase();try {

String path = calculatePath();if (log.isDebugEnabled()) {

log.debug(" Loading database from '" + path + "'");

}database.setPathname(path);database.open();

} catch (Exception e) {log.error("Opening memory database", e);throw new ServletException("Cannot load database from '" +

pathname + "'", e);}

// Make the initialized database availableservlet.getServletContext().setAttribute(Constants.DATABASE_KEY,

database);

// Setup and cache other required datasetupCache(servlet, config);

}


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destroy() of MemoryDatabasePlugin instruts-example1 sample code

public final classMemoryDatabasePlugIn implements PlugIn {.../*** Gracefully shut down this database, releasing any resources* that were allocated at initialization.*/

public void destroy() {

log.info("Finalizing memory database plug in");

if (database != null) {try {

database.close();} catch (Exception e) {

log.error("Closing memory database", e);}

}

servlet.getServletContext().removeAttribute(Constants.DATABASE_KEY);database = null;servlet = null;database = null;

config = null;


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Extension/Customization:

Extending StrutsFramework Classes


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Extending Configuration Classes

org.apache.struts.config package containsall the classes that are in-memoryrepresentations of all configuration

information in struts-config.xml file ActionConfig, ActionMapping, ExceptionConfig,

PluginConfig, MessageResourcesConfig,ControllerConfig, DataSourceConfig,

FormBeanConfig, etc You extend these classes and then specify

the extended class with class nameattribute in struts-config.xml


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Extending ActionServlet Class In Struts 1.0, it is common to extend

ActionServlet class since There was no plugin mechanism

ActionServlet handles all the controller functionalitysince there was no RequestProcessor

Rarely needed in Struts 1.1 Change web.xml

action

myPackage.myActionServlet


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Extending RequestProcessor Class

Via element in struts-config.xml process() method ofRequestProcessorclass is

called before ActionForm class is initialized and

execute() method ofAction object get called Example in struts-cookbook sample code


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Extending Action Classes

Useful to create a base Action class whencommon logic is shared among manyAction classes

Create base Action class first then subclass it foractual Action classes


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Extension/Customization:DispatchAction


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Why DispatchAction?

To allow multiple related operations toreside in a single Action class Instead of being spread over multiple Action

classes To allow common logic to be shared

Related operations typically share some commonbusiness logic


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How to use DispatchAction?

Create a class that extends DispatchAction(instead ofAction)

In a new class, add a method for everyfunction you need to perform on the service The method has the same signature as the

execute() method of an Action class

Do not override execute() method Because DispatchAction class itself provides

execute() method

Add an entry to struts-config.xml


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Example: ItemAction class extendsDispatchActionpublic class ItemActionextends DispatchAction {

public ActionForward addItem(ActionMapping mapping,ActionForm form,HttpServletRequest request,HttpServletResponse response) throws Exception {

try {// Code for item add

} catch(Exception ex) {//exception}}

public ActionForward deleteItem(ActionMapping mapping,ActionForm form,

HttpServletRequest request,HttpServletResponse response) throws

Exception {try {

// Code for item deletion}catch(Exception ex){//exception}

}}


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Example: struts-config.xml

The method can be invoked using a URL, like this:ItemAction.do?actionType=addItem


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Extension/Customization:ForwardAction


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Why ForwardAction?

If you have the case where you don't need toperform any logic in the Action but would liketo follow the convention of going through an

Action to access a JSP, the ForwardActioncan save you from creating many emptyAction classes

The benefit of the ForwardAction is that you

don't have to create an Action class of yourown All you have to do is to declaratively configure an

Action mapping in your Struts configuration file.


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Example: ForwardAction

Suppose that you had a JSP page calledindex.jsp and instead of calling this pagedirectly, you would rather have the application

go through an Action class http://hostname/appname/home.do


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Example: ForwardAction

Another way for forwarding


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Extension/Customization:

Using MultipleStruts Configuration File


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Multiple Configuration Files

Useful for multi-developer environment At least, a single struts-config.xml file is not a

bottleneck anymore

Different from Multiple modules support


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web.xml of struts-example

action

org.apache.struts.action.ActionServlet

config

/WEB-INF/struts-config.xml,

/WEB-INF/struts-config-registration.xml

1


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struts-config-registration.xml of

struts-example sample app


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struts-config-registration.xml of

struts-example


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DynaActionForm

(Introduced in 1.1)


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Why DynaActionForm?

Issues with using ActionForm ActionForm class has to be created in Java

programming language

For each HTML form page, a new ActionFormclass has to be created

Every time HTML form page is modified (aproperty is added or remove), ActionForm class

has to be modified and recompiled DynaActionForm support is added to Struts

1.1 to address these issues


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What is DynaActionForm? org.apache.struts.action.DynaActionForm

extends ActionForm class

In DynaActionForm scheme, Properties are configured in configuration file

rather than coding

reset() method resets all the properties back totheir initial values

You can still subclass DynaActionForm to overridereset() and/or validate() methods

Version exists that works with Validator framework toprovide automatic validation


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How to Configure DynaActionForm?

Configure the properties and their types inyourstruts-config.xml file add one or more elements for

each element


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Example from struts-examplesSteve


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Types Supported by

DynaActionForm java.lang.BigDecimal, java.lang.BigInteger boolean and java.lang.Boolean byte and java.lang.Byte char and java.lang.Character java.lang.Class, double and java.lang.Double float and java.lang.Float int and java.lang.Integer long and java.lang.Long short and java.lang.Short java.lang.String

java.sql.Date, java.sql.Time, java.sql.Timestamp


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How to perform Validation with

DynaActionForm? DynaActionForm does not provide default

behavior for validate() method

You can subclass and override validate() methodbut it is not recommended

Use Validator Framework Use DynaValidatorForm class (instead of

DynaActionForm class) DynaValidatorForm class extends

DynaActionForm and provides basic fieldvalidation based on an XML file


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Example from strut-example

sample application


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Validation Framework(added to Struts 1.1 Core)


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Why Struts Validation

Framework? Issues with writing validate() method in

ActionForm classes You have to write validate() method for each

ActionForm class, which results in redundant code Changing validation logic requires recompiling

Struts validation framework addresses

these issues Validation logic is configured using built-in

validation rules as opposed to writing it in Javacode


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What is Struts Validation

Framework? Originated from generic Validator

framework from Jakarta

Struts 1.1 includes this by default Allows declarative validation for many fields

Formats Dates, Numbers, Email, Credit Card, Postal Codes

Lengths Minimum, maximum

Ranges


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Validation Rules

Rules are tied to specific fields in a form Basic Validation Rules are built-in in the

Struts 1.1 core distribution e.g. required, minLength, maxLength, etc.

The built-in validation rules come withJavascript that allows you to do client side

validation Custom Validation rules can be created and

added to the definition file. Can also define regular expressions


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Validation Framework:

How toconfigure and useValidation framework?


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Things to do in order to use

Validator framework Configure Validator Plug-in Configure validation.xml file (and validation-

rules.xml file) Extend Validator ActionForms or Dynamic

ActionForms Set validate=true on Action Mappings Include the tag for client

side validation in the form's JSP page


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How to Configure Validator Plug-

in Validator Plug-in should be configured in

the Struts configuration file

Just add the following element


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Two Validator Configuration Files

validation-rules.xml Contains global set of validation rules

Provided by Struts framework

validation.xml Application specific

Provided by application developer

It specifies which validation rules from validation-rules.xml file are used by a particular ActionForm

No need to write validate() code in ActionFormclass


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Validation Framework:validation-rules.xml


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Built-in (basic) Validation Rules

required, requiredif minlength maxlength mask byte, short, integer, long, float, double date, range, intRange, floatRange creditCard, email


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validation-rules.xml: Built-inrequired validation rule

var isValid = true;...


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validation-rules.xml: Built-in

minlength validation rule

var isValid = true;var focusField = null;...


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Attributes of

Element name: logical name of the validation rule classname, method: class and method that

contains the validation logic methodParams: comma-delimited list of

parameters for the method msg: key from the resource bundle

Validator framework uses this to look up a messagefrom Struts resource bundle

depends: other validation rules that shouldbe called first


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Built-in Error Messages From Validator

Framework# Built-in error messages for validator framework checks# You have to add the following to your application's resource bundleerrors.required={0} is required.errors.minlength={0} cannot be less than {1} characters.

errors.maxlength={0} cannot be greater than {2} characters.errors.invalid={0} is invalid.errors.byte={0} must be an byte.errors.short={0} must be an short.errors.integer={0} must be an integer.errors.long={0} must be an long.

errors.float={0} must be an float.errors.double={0} must be an double.errors.date={0} is not a date.errors.range={0} is not in the range {1} through {2}.errors.creditcard={0} is not a valid credit card number.errors.email={0} is an invalid e-mail address.


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Validation Framework:validation.xml


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validation.xml: logonForm (from

struts-examples sample code)

maxlength16

minlength3


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validation.xml: logonForm (from


maxlength16

minlength3


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validation.xml: registrationForm (from


-


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Element

Defines a set of fields to be validated

Attributes Name: Corresponds name attribute of

in struts-config.xml


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struts-config.xml: logonForm (from



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Element

Corresponds to a property in an ActionForm

arg3?, var*)>

Attributes property: name of a property (in an ActionForm) that

is to be validated

depends: comma-delimited list of validation rules to

apply against this field All validation rules have to succeed


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Element: child

element Allows you to specify an alternate message

for a field element

name: specifies rule with which the msg is used, shouldbe one of the rules in validation-rules.xml

key: specifies key from the resource bundle that shouldbe added to the ActionError if validation fails

resource: if set to false, the value of key is taken asliteral string


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Element: child

element

Are used to pass additional values to the message

is the 1st

replacement and is the 2nd

replacement, and so on


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Element: child

element......

Set parameters that a field element may

need to pass to one of its validation rulessuch as minimum and miximum values in arange validation

Referenced by elements using ${var:var-name} syntax


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How do you useActionForm with

Validator?


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ActionForm and Validator

You cannot use ActionForm class with theValidator Instead you need to use special subclasses of

ActionForm class

Validator supports two types specialActionForms Standard ActionForms

ValidatorActionForm

ValidatorForm

Dynamic ActionForms DynaValidatorActionForm

DynaValidatorForm


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Choices You have

Standard ActionForms or DynamicActionForms? (rehash) If you want to specify ActionForms declaratively,

use dynamic ActionForms

xValidatorActionForm or xValidatorForm? Use xValidatorActionForm if you want more fine-

grained control over which validation rules areexecuted

In general, xValidatorForm should be sufficient


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Validation Framework:struts-exampleSample code


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struts-config.xml:

DynaValidatorForm


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validation-rules.xml: Built-inrequired validation rule



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validation-rules.xml: Built-in

minlength validation rule

var isValid = true;var focusField = null;...


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validation.xml: logonForm

maxlength16

minlength3


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ApplicationResources.Properties

# Standard error messages for validator framework checkserrors.required={0} is required.errors.minlength={0} cannot be less than {1} characters.errors.maxlength={0} cannot be greater than {2} characters.errors.invalid={0} is invalid.errors.byte={0} must be an byte.

errors.short={0} must be an short.errors.integer={0} must be an integer.errors.long={0} must be an long.errors.float={0} must be an float.errors.double={0} must be an double.errors.date={0} is not a date.errors.range={0} is not in the range {1} through {2}.

errors.creditcard={0} is not a valid credit card number.errors.email={0} is an invalid e-mail address.


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LogonForm Validation: required


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LogonForm Validation: minlength


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LogonForm Validation: maxlength


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struts-config.xml: Regular ActionFormclass (actually extension of it)


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SubscriptionForm class

public final class SubscriptionForm extends ActionForm {...public String getAction() {

return (this.action);}

public void setAction(String action) {this.action = action;

}...

public ActionErrors validate(ActionMapping mapping,HttpServletRequest request) {

...}

...}


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How to performClient-side Validationusing JavaScript?


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JavaScript Support in Validator

Framework The Validator framework is also capable of

generating JavaScript for your Strutsapplication using the same framework as for

server-side validation By using a set of JSP custom tags designed

specifically for this purpose


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Configuring validation-rules.xml

for JavaScript A custom tag is used to generate client-side

validation based on ajavascript attributebeing present within the element

in the validation-rules.xml file Use thecustom tag in your JSP page

The text from element is written to the

JSP page to provide client-side validation


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Configuring validation-rules.xml forJavaScript



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Validation Rules for the

logonForm in validation.xml

...

...


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logon.jsp Page (from struts-

example sample code)


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Things You Have to Do in your JSP

Page You will have to add an onsubmit event

handler for the form manually When the form is submitted, the

validateLogonForm( ) JavaScript function willbe invoked The validation rules will be executed, and if one or

more rules fail, the form will not be submitted.


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Things You Have to Do in your JSP

Page The tag generates a

function with the name validateXXX( ) ,where XXX is the name of the ActionForm Thus, if your ActionForm is called logonForm, the

javascript tag will create a JavaScript function calledvalidateLogonForm( ) that executes the validationlogic

This is why the onsubmit( ) event handler called thevalidateLogonForm( ) function.


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logon.jsp Page (from struts-

example sample code)

:

...


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I18N andValidation


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I18N and Validator Validator framework uses Struts resource

bundle element in validation.xml supports

language, country, variant...

...

...


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Advanced Featuresof Validator


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Advanced Features

Creating custom validators Using programmatic validation along with

Validator


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DeclarativeException Handling


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Why Declarative Exception Handling?

Previously (Struts 1.0), Action class has todeal with all business logic exceptions itself No common exception handling

Rather difficult to implement


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What is Declarative Exception Handling?

Exception handling policy is declarativelyspecified in struts-config.xml Exceptions that may occur

What to do if exceptions occur

Can be global and per-Action From a particular Exception class or super class

To an application-relative path

Requires a small change to your Action toleverage this feature ...


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Example in struts-example


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How Does it Work?

When an Exception is thrown inside execute()ofAction class, processException() method ofRequestProcessorclass is called

processException() method checks if element is configured for thatspecific exception type

If there is, Default exception handler creates and stores an

ActionErrorinto the specified scope

Control is then forwarded to the resource specifiedin path attribute


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Example in struts-example1

public ActionForwardexecute

(ActionMapping mapping,

ActionForm form,

HttpServletRequest request,

HttpServletResponse response)

throws Exception {

...

throw new PasswordExpiredException(...);

...

}


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Customizing Exception Handling

Create a class that extendsorg.apache.struts.action.ExceptionHandler Override execute() method

public ActionForward execute( Exception ex,ExceptionConfig exConfig,

ActionMapping mapping,

ActionForm formInstance,

HttpServletRequest request,HttpServletResponse response

) throws ServletException;


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Configure the Custom Exception Handler(globally or per action basis)


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Multiple Custom Exception Handlers


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Application Modules

Wh t A li ti M d l ?


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What are Application Modules?

Allows a single Struts application to be splitinto multiple modules Each module has its own Struts configuration file,

JSP pages, Actions

Multiple Application Module


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Multiple Application ModuleSupport

Necessary for large scale applications Allows parallel development

Design goals: Support multiple independent Struts configurationfiles in the same application

Modules are identified by an "application prefix"that follows the context path

Existing Struts-based applications should be ableto be installed individually, or as a sub-application,with no changes to the pages, Actions, formbeans, or other code

Multiple Application Modules Support


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Multiple Application Modules Support

Implications of the design goals: "Default" sub-application with a zero-length prefix

(like the ROOT context in Tomcat)

"Context-relative" paths must now be treated as

"sub-application-relative" ActionServlet initialization parameters migrate to

the Struts configuration file

Controller must identify the relevant sub-application, and make its resources available (asrequest attributes)

APIs must be reviewed for assumptions aboutthere being (for example) only one set ofActionMappings


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Application Modules:

How to configuremodules

How to set up and use multiple


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How to set up and use multiple

Application Modules? Prepare a config file for each module. Inform the controller of your module.

Use actions to refer to your pages.


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Informing the Controller

In web.xml...config

/WEB-INF/conf/struts-default.xmlconfig/module1/WEB-INF/conf/struts-module1.xml

...


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Application Modules:How to switch modules


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Methods for Switching Modules

Two basic methods to switching from onemodule to another Use a forward (global or local) and specify the

contextRelative attribute with a value oftrue Use the built-in

org.apache.struts.actions.SwitchAction


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Global Forward......

......


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Local Forward.........

......


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org.apache.struts.actions.SwitchAction

.........


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How to change module To change module, use URI

http://localhost:8080/toModule.do?prefix=/moduleB&page=/index.do

If you are using the "default" module as wellas "named" modules (like "/moduleB"), youcan switch back to the "default" modulewith a URI

http://localhost:8080/toModule.do?prefix=&page=/index.do


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Struts ELTag library

St t EL E t i


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Struts EL Extension

Extension of the Struts tag library Uses the expression evaluation engine in the

Jakarta Taglibs implementation of the JSP

Standard Tag Library (version 1.0) to evaluateattribute values Some of the Struts tags were not ported to this

library

their functionality was entirely supplied by theJSTL

Requires the use of the Struts tag library, andthe Java Server Pages Standard Tag Library

T M i


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Tag Mapping

Every Struts tag that provides a feature thatis not covered by the JSTL (1.0) library ismapped into the Struts-EL library

Bean Tag Library Tags NOT Implementedin Struts-EL cookie (in Struts): c:set, EL (in JSTL)

define (in Struts), c:set, EL (In JSTL)

H t St t EL


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How to use Struts EL

Struts

Struts EL


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Struts &Security

JAAS


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JAAS

Struts 1.1 and later offers direct support forthe standard Java Authentication andAuthorization Service (JAAS)

You can now specify security roles on anaction-by-action basis

SSL E tension (ssle t)


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SSL Extension (sslext)

Extension to Struts 1.1 http://sslext.sourceforge.net

Extends the ActionConfig class,

RequestProcessor, and Plugin classes todefine a framework where developers mayspecify the transmission protocol behavior forStruts applications

Within the Struts configuration file, developersspecify which action requests require HTTPStransmission and which should use HTTP



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Can also specify whether to redirect"improperly-protocoled" requests to the correctprotocol

and tag extension Struts actions specified in either of these tags are

analyzed to determine the protocol that should beused in requesting that action

The HTML generated by these tags will specify theproper protocol


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Commons:DynaBeans

CO O S S


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COMMONS-BEANUTILS

Pluggable type converters Mapped properties

contact.phone(Work)

DynaBeans Transparently supported by BeanUtils and

PropertyUtils

Commons-Beanutils --


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Commons Beanutils

DynaBeanspublic interface DynaBean {public Object get(String name);

public Object get(String name, int index);

public Object get(String name, String key);

public void set(String name, Object value);

public void set(String name, int index, Objectvalue);

public void set(String name, String key,Object value);

}


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Struts Utilities

Utilities


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Utilities org.apache.struts.utilpackage Families of classes that solve common

web app problems.

Suitable for general Java programmingand are worth checking out Utilities classes include:

Beans & Properties

Collection Classes JDBC connection pool

Message Resources

Utility Classes


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Utility Classes common-*.jar Now required for Struts

Might require some package renaming for 1.0.2 Strutsapps

Many utilities are now located in the JakartaCommons project http://jakarta.apache.org/commons/

BeanUtils Package org.apache.commons.beanutils

Collections Package org.apache.commons.collections

Digester Package org.apache.commons.digester


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BeanUtil & PropertyUtil

Relies on using Java Reflection tomanipulate Java Beans

Used throughout Struts (IteratorTag,

WriteTag) Need to make sure you have a valid bean!

Null constructor

Public class declaration

Mutator/Accessor methods

XML Parsing


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XML Parsing

Digester package provides for rules-basedprocessing of arbitrary XML documents.

Higher level, more developer-friendly

interface to SAX events Digester automatically navigates the element

hierarchy of the XML document Element Matching Patterns

Processing Rule


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AccessingDatabase

R d ti Fi t


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Recommendation First Database access logic belong to business

logic (Model) Action class should be just a thin layer to

Model All the database access code should be

encapsulated in the business logic

Struts doesn't know what persistent layer you are

using (or even if there is a persistence layer) Use database access logic of your model

component (EJB, JDO, etc.) if possible


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Example in struts-config xml


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Example in struts-config.xml


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Struts andJ2EE Patterns

Struts and Core J2EE Patterns


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St uts a d Co e J atte s

Client

Action

ServletAction

Action

Forward

Action

FormJSP View

Request

Response

uses

Controller Model

View Helper

View

ActionMapping

(xml)

Service

Interface

Business

Service

Business

Delegate

Service

Locator

Struts and Core J2EE Patterns


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Composite View

Front Controller Business Delegate

Compsite Entity

DataTransfer Object

Session Facade

DataTransfer Object

P resentationRequestContr oller Cr ea teAccountD ispatcher User AccountManager Delegate

EJBSessionBean

UserA ccountManagerEJB

EJBEntityBean

UserA ccountEJB

EJBEntityB ean

CreditCardEJB

CreditCardValuesUserAccountValues

ServerPagetemplate.jsp

ServerPagemenu.jsp

JSPInclude

+ themenu.jsp

ServerPagenew_account.jsp

ServerPagenew_account_confirm.jsp

ActionActionServlet


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Nested Tag Library

The "Nested" Tag Library


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The Nested Tag Library

Brings a nested context to the functionality ofthe Struts custom tag library

Written in a layer that extends the current

Struts tags, building on their logic andfunctionality The layer enables the tags to be aware of the tags

which surround them so they can correctly provide

the nesting property reference to the Struts system

The "Nested" Tag Library


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The Nested Tag Library Nested tags allow you to establish a default

bean for nested property references 1:1 correspondence, and identical

functionality, of other Struts tags Except the "name" property gets set for you

automatically ...

Example: Scenario


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Example: Scenario Company has many departments

Company bean has a collection of Departmentbeans

Each department has many employees Department bean has a collection of Employee

beans

Example: Suppose You WantT Di l th f ll i


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To Display the following...

Example: Using JSTL for


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gIterating Nested Beans

COMPANY:

Department:

Employee:

E-mail:

Example: Using Nested Tag for


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p g gDoing the Same ThingCOMPANY:

Department:

Employee:

E-mail:

Example 2:


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Example 2:

Before using the nested tags:

After using the nested tags:


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Changes BetweenStruts 1.0 & 1.1

Struts 1 1 ActionServlet


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Struts 1.1 ActionServlet

Introduction of request processor Via RequestProcessorclass

Handles much of the functionality of ActionServlet

in Struts1.0 ActionServlet in 1.1 is a thin layer

Allows developers to customize the requesthandling behavior more easily

Struts 1 1 Actions


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Struts 1.1 Actions

Method perform() replaced by execute() Backwards compatible

Change necessary to support declarative

exception handling Addition ofDispatchAction class

Supports multiple business methods instead of asingle execute() method

Allows easy group of related business methods

Changes to web.xml and


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struts-config.xml web.xml

Serveral initialization parameters removed Uses elements in struts-config.xml

Supports a few new parameters

New Features in Struts 1 1


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New Features in Struts 1.1

Plug-ins Dynamic ActionForms

Multiple application modules Declative exception handling Validator framework

Nested tags Dependency to Commons projects Action-based authentication


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Roadmap


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Passion!

Documents

Advanced Struts