Java Server Pages 2nd Edition phần 9 ppsx

Attributes Attribute name Java type Dynamic value accepted Description A custom pattern in the form accepted by java.util.Locale Yes A locale to be used instead of the default.. Synta

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For a number type, the format specification can be currency, percent, integer, or

the type of customized pattern described for <fmt:formatNumber>

<fmt:parseDate>

The <fmt:parseDate> action parses a date and time value formatted according to

locale-specific rules A custom pattern can be specified, or locale-dependent default patterns for one

or both of the date portion and the time portion can be selected

The locale used is the one explicitly specified or is taken from the locale configuration setting

or the locale from the localization context setting If none of these are set, the locale is

determined as the best match for the user preferences (Accept-Language request header)

Syntax 1: Without a body

<fmt:parseDate value="dateAndTime"

[var="var" [scope="page|request|session|application"]] />

Syntax 2: With a body

A custom pattern in the form accepted by

java.text.SimpleDateFormat; see fmt:formatDate

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dateStyle String Yes One of the predefined

locale-dependent date patterns

locale-dependent time patterns

The locale used is the one explicitly specified or is taken from the locale configuration setting

or the locale from the localization context setting If none of these are set, the locale is determined as the best match for the user preferences (Accept-Language request header)

<fmt:parseNumber value="number"

[pattern="pattern" | type="number|currency|percent"]

[parseLocale="locale"]

[integerOnly="true|false"]

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Attributes

Attribute

name Java type

Dynamic value accepted Description

A custom pattern in the form accepted by

java.util.Locale Yes A locale to be used instead of the default

integerOnly boolean Yes Set to true to parse only the integer

portion

var String No The variable name The type is Number

from ISO-8859-1 The encoding can be specified explicitly I can also be determined based on

the request Content-Type header, if any, or the encoding session variable set by all JSTL

actions that set the locale for a response (javax.servlet.jsp.jstl.fmt.request.charset)

Syntax 1: Without parameters

<fmt:requestEncoding [value="encodingName"] />

Attributes

Attribute name Java type Dynamic value accepted Description

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Example

<%

Sets the request encoding to the same encoding as was used for

the previous response in the current session

>

<fmt:requestEncoding />

<fmt:setBundle>

The <fmt:setBundle> action sets the localization context configuration variable, which

establishes the localization context for all other JSTL actions that rely on one and disables the

locale lookup based on user preferences Alternatively, the localization context may be saved

as a scoped variable and provided as explicit input to other actions

The localization context contains a locale and the best match for the specified resource

bundle The locale for the localization context is either the locale defined by the locale

configuration setting or the best match for the user preferences specified by the

Accept-Language HTTP request header

java.util.ResourceBundle for details

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<fmt:setLocale>

The <fmt:setLocale> action sets the locale configuration variable, establishing the locale for all other JSTL actions that rely on a locale, disabling the locale lookup based on user preferences

Description

java.util.Locale Yes

The locale If set as a String, it must

be an ISO-639 language code, optionally followed by an ISO-3166 country code and separated by a hyphen

or an underscore character

java.util.Locale for details

scope String No The configuration variable scope

Syntax

<fmt:setTimeZone value="timeZone"

[var="var"] [scope="page|request|session|application"] />

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Attributes

Attribute

name Java type

Dynamic value accepted Description

java.util.TimeZone Yes

The time zone If specified as a String, it's an abbreviation, a name, or a GMT offset; see java.util.TimeZone for details

The variable name If omitted, the action sets the time-zone context configuration variable The type is

The time zone If specified as a

String, it's an abbreviation, a name, or a GMT offset; see

java.util.TimeZone for details

Example

<fmt:timeZone value="America/Los Angeles">

<fmt:formatDate value="${now}" type="both" />

</fmt:timeZone>

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B.4 Database Access Actions

<sql:dateParam>

The <sql:dateParam> action is used as a nested action for <sql:query> and

<sql:update> update to supply a date and time value for a value placeholder If a nullvalue is provided, the value is set to SQL NULL for the placeholder To ensure portability between different database engines, this action must be used when setting values for DATE,

TIME, and TIMESTAMP columns

The value must be of type java.util.Date or one of the SQL specific subclasses:

java.sql.Date, java.sql.Time, or java.sql.Timestamp If it's a

java.util.Date, the action converts it to the specified subclass

Syntax

<sql:dateParam value="parameterValue"

[type="timestamp|time|date"] />

Attributes

Attributename Java type Dynamic valueaccepted Description

value java.util.Date Yes The parameter value

type String Yes The SQL type the value should be converted to, if needed

The <sql:param> action is used as a nested action for <sql:query> and

<sql:update> to supply a value for a value placeholder If a null value is provided, the value is set to SQL NULL for the placeholder To ensure portability between different database engines, the value type must be a supported type for the target column, for instance a numeric value for an INT or FLOAT column, and a String value for a CHAR or VARCHAR

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column See <sql:dateParam> for setting values for DATE, TIME, and TIMESTAMPcolumns

<sql:param value="parameterValue" />

<sql:param>

parameterValue

</sql:param>

Attributes

The action uses a connection provided by an <sql:transaction> action, or

transaction action or if not part of a transaction from the explicitly specified data source or the data-source configuration setting The number of rows to retrieve can be limited explicitly or with the maximum rows configuration setting

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Syntax 2: With a body for parameters

The data source to use If specified as a

String, it can be either a JNDI path or a list

of JDBC parameters as described for the datasource configuration setting

maxRows int Yes The maximum number of rows to include in theresult If omitted or -1, all rows are included

startRow int Yes The 0-based index for the first row to include inthe result

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<sql:setDataSource>

The <sql:setDataSource> action sets the data source configuration variable or saves the data-source information in a scoped variable that can be used as input to the other JSTL database actions

This action is primarily intended for prototyping and small, simple applications See Chapter 11 and Chapter 23 for alternative ways to make a data source available

The variable name If omitted, the data-source configuration variable is set The type is either

javax.sql.DataSource or

String

scope String No The variable or configuration variable scope

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The <sql:transaction> action establishes a transaction context for a set of

<sql:query> and <sql:update> actions It ensures that the database modifications performed by the nested actions are either committed or rolled back if an exception is thrown

by any nested action

The action provides a connection to the nested database actions, either from the explicitly specified data source or from the data-source configuration setting

The transaction isolation level If omitted, the isolation level the data source has been configured with is used

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The <sql:update> action executes an SQL statement that updates the database, such as an

INSERT, UPDATE, or DELETE statement, and optionally saves the number of affected rows in

a scoped variable SQL DDL statements, such as CREATE TABLE, can also be executed with this action The statement may contain question marks as placeholders for values assigned by nested <sql:param> actions

The action uses a connection provided by an <sql:transaction> action, or if not part of

a transaction, from the explicitly specified data source or the data-source configuration setting

<sql:update sql="sqlStatement"

[dataSource="dataSource"]

Syntax 2: With a body for parameters

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Syntax 3: With a body for the statement and parameters

Description

javax.sql.DataSourceYes

The data source to use If specified as a

String, it can be either a JNDI path or a list

of JDBC parameters as described for the source configuration setting

The <x:choose> action controls the processing of nested <x:when> and

<x:otherwise> actions It allows only the first <x:when> action with a test expression

that evaluates to true to be processed, or gives the go-ahead to the single <x:otherwise>

action if none do

Syntax

<x:choose>

<x:when> actions and optionally one <x:otherwise> action

</x:choose>

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var String No The name of the nested variable holding the

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<x:if>

The <x:if> action evaluates its body only if the specified XPath expression evaluates to

true Alternatively, the evaluation result can be saved as a scoped Boolean variable

<x:if select="booleanXPathExpression"

var="var" [scope="page|request|session|application"]/>

<x:if select="booleanXPathExpression">

Dynamic value

select String No The XPath expression to evaluate

Syntax

<x:otherwise>

JSP elements

</x:otherwise>

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escapeXml boolean Yes If true, the characters < > & ' " are converted to

the corresponding XML character entity codes

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Attributes

Example

<x:transform xml="${doc}" xslt="${stylesheet}">

<x:param name="custId" value="${param.id}" />

</x:transform>

<x:parse>

The <x:parse> action parses an XML document and saves the result either as a standard

org.w3c.dom.Document object or as an implementation-dependent object

[var="var" [scope="page|request|session|application"] |

varDom="var" [scopeDom="page|request|session|application"]]

xml String or Reader Yes The XML document

A URI to use as a base for relative references in the document, as an absolute URL, or as a page- or context-relative path

filter org.xml.sax.XMLFilterYes A filter that can remove elements that

aren't of interest

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var String No The variable name The type is

implementation-dependent

<x:set select="XPathExpression"

var="var" [scope="page|request|session|application"] />

Attributes

Attribute

name Java type Dynamic value accepted Description

The variable name The type is the type of the expression evaluation, converted to the corresponding Java type

scope String No The variable scope

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captured or processed further by a javax.xml.transform.Result object Nested

<x:param> actions can supply values for parameters used in the stylesheet

<x:transform xml="XMLDocument" xslt="XSLTStylesheet"

[xmlSystemId="systemId"] [xsltSystemId="systemId"]

[var="var" [scope="page|request|session|application"] |

result="resultObject"] />

Syntax 2: With a body for parameter values

<x:transform xml="XMLDocument" xslt="XSLTStylesheet"

[xmlSystemId="systemId"] [xsltSystemId="systemId"]

[var="var" [scope="page|request|session|application"] |

xml

String, Reader,

javax.transformation.Source,

org.w3c.dom.Document, or object exposed by x:parse or x:set

Yes The XML document

javax.transformation.Source Yes The XSLT stylesheet

A URI to use as a base for relative references in the document, as an absolute URL or as a page- or context-relative path

A URI to use as a base for relative references in the stylesheet, as an absolute URL or as a page- or context-relative path

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result javax.xml.transform.Result Yes Object that captures or

processes the result

The <x:when> action represents one of the mutually exclusive alternatives within a

<x:choose> block It evaluates its body only if it's the first <x:when> action in the block with a test expression that evaluates to true

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B.6 Support and Utility Types

Returns the value of test condition This method must be implemented by the subclass

public void setScope(String scope)

Sets the scope attribute value

public void setVar(String var)

Sets the var attribute value

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public static String getLocalizedMessage(javax.servlet.jsp.PageContext p,

String key, String basename)

Returns the message matching the key from the specified resource bundle and the locale specified by the locale context setting or the localization context setting, or ???key??? if the key isn't found

String key, Object[] params)

Returns the parameterized message matching the key from the resource bundle and locale specified by the localization context setting, or ???key??? if the key isn't found

String key, Object[] params, String basename)

Returns the parameterized message matching the key from the specified resource bundle and the locale specified by the locale context setting or the localization context setting, or

???key??? if the key isn't found

Creates an empty context

public LocalizationContext(java.util.ResourceBundle bundle)

Creates a context with the specified resource bundle but no locale

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public LocalizationContext(java.util.ResourceBundle bundle,

java.util.Locale locale)

Creates a context with the specified resource bundle and locale

Methods

public java.util.ResourceBundle getResourceBundle( )

Returns the resource bundle

public java.util.Locale getLocale( )

Returns the locale

LoopTag

The LoopTag interface is implemented by tag handlers for iteration actions, such as the

<c:forEach> action Its methods provide access to the current iteration element and the iteration status

public Object getCurrent( )

Returns the current iteration element

public javax.servlet.jsp.jstl.core.LoopTagStatus getLoopStatus( )

Returns the iteration status

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public Integer getBegin( )

Returns the begin attribute value for the associated action element or null if not specified

public int getCount( )

Returns the current 1-based iteration count

public Object getCurrent( )

public int getIndex( )

Returns the current 0-based iteration index

public Integer getStart( )

Returns the start attribute value for the associated action element or null if not specified

public Integer getStep( )

Returns the step attribute value for the associated action element or null if not specified

public boolean isFirst( )

Returns true for the first iteration round

public boolean isLast( )

Returns true for the last iteration round

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protected int begin

protected boolean beginSpecified

protected int end

protected boolean endSpecified

protected int itemId

protected int statusId

protected int step

protected boolean stepSpecified

Methods

public void doAfterBody( ) throws javax.servlet.jsp.tagext.JspTagException

Prepares for the next iteration until hasNext( ) returns false

public void doCatch(Throwable t) throws Throwable

Rethrows the exception

public void doFinally( ) throws javax.servlet.jsp.tagext.JspTagException

Removes the nested variables

public void doStartTag( ) throws javax.servlet.jsp.tagext.JspTagException

Prepares for the iteration

protected abstract Object getCurrent( )

public javax.servlet.jsp.jstl.core.LoopTagStatus getLoopStatus( )

Returns the iteration status

protected abstract boolean hasNext( )

throws javax.servlet.jsp.tagext.JspTagException

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Returns true if there are more iteration elements

protected abstract Object next( )

Returns the next iteration element

protected abstract void prepare( )

Prepares for the iteration

public void setScope(String scope)

Sets the scope attribute value

public void setVar(String var)

Sets the var attribute value

protected void validateBegin( )

Throws an exception if the begin attribute has an invalid value

protected void validateEnd( )

Throws an exception if the end attribute has an invalid value

protected void validateStep( )

Throws an exception if the end attribute has an invalid value

The LoopTagSupport class can be extended by a tag handler for a custom iteration action

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Methods

public java.util.SortedMap[] getRows( )

Returns an array of SortedMap objects Each array element represents a row, and the map contains the column values, with the column name as a case-insensitive key public Object[][] getRowsByIndex( )

Returns an array of arrays The first array dimension represents rows, and the second represents the column values

public String[] getColumnNames( )

Returns an array of String objects, representing the column values in the same order

as in the arrays returned by getRowsByIndex( )

public boolean isLimitedByMaxRows( )

Returns true if the result was limited by the maximum row configuration setting or action element attributes

Returns a Result object with the data from the specified ResultSet

public static javax.servlet.jsp.jstl.sql.Result

toResult(java.sql.ResultSet rs, int maxRows)

Returns a Result object with the data from the specified ResultSet, up to the specified number of maximum rows

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SQLExecutionTag

The SQLExecutionTag interface is implemented by the <sql:query> and

<sql:update> tag handlers so that they can receive placeholder parameter values from

public void addSQLParameter(Object value)

Adds a parameter value to use with

java.sql.PreparedStatement.setObject( )

B.7 Configuration Settings

Data Source

The data-source configuration setting can be set as a String in this format, in which optional

parts are embedded in brackets:

url [, [driver] [, [user] [, [password]]]

This type of value creates a simple DataSource without any pooling capabilities and is

intended only for prototype and low-end applications, as described in Chapter 11 It can also

be set to a JNDI path for a DataSource made available by the container, or to a

DataSource created by custom code, such as a servlet or listener These options are

described in detail in Chapter 23

Details

Variable name: javax.servlet.jsp.jstl.sql.dataSource

Java constant: Config.SQL_DATA_SOURCE

Java type: String or javax.sql.DataSource

Set by: <sql:setDataSource>, context parameter, or custom code

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Used by: <sql:query>, <sql:update>, and <sql:transaction>

Fallback Locale

Setting the fallback locale configuration setting provides a default locale to be used when the lookup of a locale based on user preferences (passed through the Accept-Language header value) fails to match an available locale When a String value is used to set these two variables, it must be specified as a two-letter lowercase ISO-639 language code, optionally followed by a two-letter uppercase ISO-3166 country code, separated by a hyphen or an underscore character

Java type: String or java.util.Locale

Set by: Context parameter or custom code

Used by: <fmt:bundle>

Java type: String or java.util.Locale

Set by: <fmt:setLocale>, context parameter, or custom code

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Used by: <fmt:bundle>

LocalizationContext class, which contains references to both a locale and a resource bundle for a locale

<fmt:parseNumber>,<fmt:formatDate>, and <fmt:parseDate>

Set by: Context parameter or custom code

Used by: <sql:query>

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Time Zone

The time zone configuration setting provides a default time zone for the JSTL actions formatting and parsing dates String values for the time-zone setting must be of the type defined for the java.util.TimeZone class: an abbreviation, a full name, or a GMT offset

Details

Variable name: javax.servlet.jsp.jstl.fmt.timeZone

Java constant: Config.FMT_TIME_ZONE

Java type: String or java.util.TimeZone

Set by: <fmt:setTimeZone>, context parameter, or custom code

Used by: <fmt:formatDate> and <fmt:parseDate>

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