SigmaInfoSolution_Hussain Akhtar Wahid

8/2/2019 SigmaInfoSolution_Hussain Akhtar Wahid

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A Presentation On

Struts Taglib

By :-

Hussain Akhtar WahidASE(Sigma InfoSolutions)

Emp Id : 335


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IntroductionStrut Taglib is the new library of tags as an

advanced version of the JSP Taglib .It hassome extra features and also immutablecompatibility with all the action forms ,

specially required for nested action formor action form series.


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Types

1. HTML

2. Bean

3. Logic

4. Nested


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HTML

This taglib contains tags used tocreate struts input forms, as well

as other tags generally useful inthe creation of HTML-based user

interfaces.


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Bean

1 : Some features are also in the JSPStandard Tag Library (JSTL).

2 : Standard tags over the Struts specifictags are encouraged3 : easy accessing beans and their

properties4 : defining new beans5 : easy bean creationon the value of

request cookies, headers, and


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Bean

cookie define

header include

message page

parameter resource

size struts

write


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Logic

This tag library contains tags that are useful inmanaging conditional generation of output

text, looping over object collections forrepetitive generation of output text, andapplication flow management.


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Logic cont...1

Rules for Comparison Tags1: Automatic type comparison2: The variable to be compared to is retrieved, based on theselector attribute3: Null will be coerced to a zero-length string before the

comparison4: Tags perform from out to in

Rules For substring matching tags1: The variable to be compared to is retrieved, based on theselector attribute2: Null is thrown as request time Exception


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Logic

empty equal forward

greaterEqual greaterThan iterate

lessEqual lessThan match

messagesNotPresent messagesPresent notEmpty

notEqual notMatch notPresent

present redirect


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Nested

This tag library brings a nested context to thefunctionality of the Struts custom tag library.

It's written in a layer that extends the currentStruts tags, building on their logic andfunctionalityThe layer enables the tags to be aware of the

tags which surround them so they can correctlyprovide the nesting property reference to theStruts system


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Nested cont...

It's all about nesting beans...A bean holds a reference to another bean internally, andall access to that bean is handled through the current

bean. This act of having one bean's access go throughanother bean is known as "nesting beans". The first beanis known as the parent bean. The bean which it references,is known as a child bean. The terms "parent" and "child"

are commonly used to describe the model's hierarchy.most parent class is calles root class


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Nestedcheckbox define empty equal

errors file form greaterEqual

greaterThan hidden image img

iterate lessEqual lessThan link

match message messages messagesNotPresent

messagesPresent multibox nest notEmpty

notEqual notMatch notPresent options

optionsCollection password present radio

root select size submit

text textarea write writeNesting


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Nested cont...

It's all about nesting beans...A bean holds a reference to another bean internally, andall access to that bean is handled through the current

bean. This act of having one bean's access go throughanother bean is known as "nesting beans". The first beanis known as the parent bean. The bean which it references,is known as a child bean. The terms "parent" and "child"

are commonly used to describe the model's hierarchy.parent-most class is called root class


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tag base1: Renders an HTML element with an href attribute

pointing to the absolute location of the enclosing JSP page.

2: This tag is valid only when nested inside an HTML element.

3: This tag is useful because it allows you to use relative URL

references in the page that are calculated based on the URL ofthe page itself, rather than the URL to which the most recentsubmit took place (which is where the browser would normallyresolve relative references against).


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Tag cancel

Render a Cancel Button

Renders an HTML element of type submit. This

tag is only valid when nested inside a form tag body.Pressing of this submit button causes the action servlet tobypass calling the associated form bean validate()method. The action is called normally.


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Tag errorsConditionally display a set of accumulated error messages.

Displays a set of error messages prepared by a business logic component and storedas an ActionMessages object, an ActionErrors object, a String, or a String array in anyscope. If such a bean is not found, nothing will be rendered.In order to use this tag successfully, you must have defined an application scopeMessageResources bean under the default attribute name, with optional definitionsof message keys specified in the following attributes:

header - Text that will be rendered before the error messages list. Typically, thismessage text will end with to start the error messages list (default

"errors.header").footer - Text that will be rendered after the error messages list. Typically, thismessage text will begin with to end the error messages list (default"errors.footer").prefix - Text that will be rendered before each individual error in the list (default"errors.prefix").

suffix - Text that will be rendered after each individual error in the list (default"errors.suffix" .


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Tag javascript

Render JavaScript validation based on the validation rules loaded by theValidatorPlugIn.

Render JavaScript validation based on the validation rules loaded by theValidatorPlugIn. The set of validation rules that should be generated isbased on the formName attribute passed in, which should match the nameattribute of the form element in the xml file.

The dynamicJavascript and staticJavascript attributes default to true, but ifdynamicJavascript is set to true and staticJavascript is set to false then onlythe dynamic JavaScript will be rendered. If dynamicJavascript is set to falseand staticJavascript is set to true then only the static JavaScript will berendered which can then be put in separate JSP page so the browser cancache the static JavaScript.


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Tag messages

Conditionally display a set of accumulated messages.

Displays a set of messages prepared by a business logic

component and stored as an ActionMessages object,ActionErrors object, a String, or a String array in any scope. Ifsuch a bean is not found, nothing will be rendered. Themessages are placed into the page scope in the body of this tag

where they can be displayed by standard JSP methods. (Forexample: ,)

In order to use this tag successfully, you must have defined anapplication scope MessageResources bean under the default

attribute name.


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Tag header

Define a scripting variable based on the value(s) of thespecified request header.

Retrieve the value of the specified request header (as a singlevalue or multiple values, depending on the multiple attribute),and define the result as a page scope attribute of type String (ifmultiple is not specified) or String[] (if multiple is specified).

If no header with the specified name can be located, and nodefault value is specified, a request time exception will bethrown.


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Tag cookie

Define a scripting variable based on the value(s) of thespecified request cookie.

Retrieve the value of the specified request cookie (as a singlevalue or multiple values, depending on the multiple attribute),and define the result as a page scope attribute of type Cookie (ifmultiple is not specified) or Cookie[] (if multiple is specified).

If no cookie with the specified name can be located, and nodefault value is specified, a request time exception will bethrown.


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Tag size

Define a bean containing the number of elements in a Collection orMap.

Given a reference to an array, Collection or Map, creates a new bean,of type java.lang.Integer, whose value is the number of elements inthat collection. You can specify the collection to be counted in anyone of the following ways:

As a runtime expression specified as the value of the collectionattribute.As a JSP bean specified by the name attribute.As the property, specified by the property attribute, of the JSP beanspecified by the name attribute.


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Tag struts

Expose a named Struts internal configuration object as a bean.

Retrieve the value of the specified Struts internal configuration

object, and define it as a scripting variable and as a page scopeattribute accessible to the remainder of the current page. You mustspecify exactly one of the formBean, forward, and mapping attributesto select the configuration object to be exposed.

If a problem occurs while retrieving the specified configurationobject, a request time exception will be thrown.


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Tag write

Render the value of the specified bean property to the current JspWriter.

Retrieve the value of the specified bean property, and render it to the current JspWriter as a String bythe ways:

If format attribute exists then value will be formatted on base of format string from format attributeand default system locale.If in resources exists format string for value data type (view format attribute description) then value

will be formatted on base of format string from resources. Resources bundle and target locale can bespecified with bundle and locale attributes. If nothing specified then default resource bundle andcurrent user locale will be used.

If there is a PropertyEditor configured for the property value's class, the getAsText() method will becalled.Otherwise, the usual toString() conversions will be applied.

When a format string is provided, numeric values are formatted using the java.text.DecimalFormatclass; if the format string came from a resource, the applyLocalisedPattern() method is used, andapplyPattern() is used otherwise. Dates are formatted using the SimpleDateFormat class. For detailsof the specific format patterns, please see the Javadocs for those classes.

If a problem occurs while retrieving the specified bean property, a request time exception will be


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logic

Forward control to the page specified by the specified ActionForwardentry.

Performs a PageContext.forward() orHttpServletResponse.sendRedirect() call for the global

ActionForward entry for the specified name. URL rewriting willoccur automatically if a redirect is performed.

Tag forward


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Tag iterate

Render an internationalized message string to the response.

Retrieves an internationalized message for the specified locale, using

the specified message key, and write it to the output stream. Up tofive parametric replacements (such as "{0}") may be specified.

The message key may be specified directly, using the key attribute, orindirectly, using the name and property attributes to obtain it from a

bean.

JSTL: The equivalent JSTL tag is . For example,


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Tag match

Evaluate the nested body content of this tag if the specified value isan appropriate substring of the requested variable.

Matches the variable specified by one of the selector attributes (as aString) against the specified constant value. If the value is a substring(appropriately limited by the location attribute), the nested bodycontent of this tag is evaluated.


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Pitfalls Of JSP

1 : Hard-Coded Strings in JSPs2 : Hard-Coded Keys in JSPs3 : Not Using Struts Tags for Error Messaging4 : Calculating Derived Values in JSPs5 : Performing Business Logic in JSPs6 : Hard-Coded Options in HTML Select Lists7 : Not Checking for Duplicate Form Submissions


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Step-by-Step1. Create a Constants class.a. Depending on which approach is taken to the replacement ofconstant keys in the JSP, you might also need to create accessors

for each property constant.2. Begin with a single, simple JSP.a. Keep in mind that you will be repeating these steps, so it is bestto start simple and work your way up.b. Another equally valid approach is to go through your homepage, then each page that is accessible from there and so on until

you have covered all the pages.

3. Search for hard-coded keys.4. Create a new constant in the Java class for each unique key.a. Keep in mind that if there are a lot of constants, say more than 30or 40 as a rule of thumb, the constants should be grouped andsplit into separate classes.5. Replace each hard-coded key with a reference to the appropriateconstant.

a. Or use an expression referring to the property.6. Test the changes.7. Continue with the next JSP, until all keys have been replaced withthe constant.


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Hussain Akhtar Wahid

ASE(Sigma InfoSolutions)

Emp Id : 335

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SigmaInfoSolution_Hussain Akhtar Wahid