jstl教程
jstl教程
JavaServer Pages标准标记库(JSTL)是一个有用的JSP标签的集合,它封装了许多JSP应用程序通用的核心功能。
JSTL支持常见的,结构性任务,如迭代和条件,标签为操纵XML文件,国际化标签和SQL标签。它还提供了一个框架,将现有的自定义标签和JSTL标签。
JSTL标签进行分类,根据其功能分为以下,可用于创建一个JSP页面时,JSTL标签库组:
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核心标签(Core Tags)
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格式化标签(Formatting tags)
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SQL标签(SQL tags)
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XML标签(XML tags)
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JSTL函数(JSTL Functions)
安装JSTL库:
如果您使用的是Apache Tomcat容器,那么按照下面两个简单的步骤:
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下载的二进制发行版,从Apache标准标记库和解压的压缩文件。
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使用标准的标签库从Jakarta Taglibs分布,复制发行版'lib'目录到应用程序的JAR文件 webapps\ROOT\WEB-INF\lib 目录中。
要使用JSTL库,要在每一个JSP的顶部,使用该库必须包括一个<taglib>指令。
核心标签:
核心组的标签是最常用的JSTL标签。以下是在您的JSP的语法包括JSTL核心库:
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
有以下核心JSTL标签:
Tag | Description |
---|---|
<c:out > | 和<%= ... >标签一样功能, 但对于表达式。 |
<c:set > | 设置表达式求值的结果在一个'范围' |
<c:remove > | 删除一个范围的变量(从一个特定的范围内,如果已指定)。 |
<c:catch> | Catches any Throwable that occurs in its body and optionally exposes it. |
<c:if> | Simple conditional tag which evalutes its body if the supplied condition is true. |
<c:choose> | Simple conditional tag that establishes a context for mutually exclusive conditional operations, marked by <when> and <otherwise> |
<c:when> | Subtag of <choose> that includes its body if its condition evalutes to 'true'. |
<c:otherwise > | Subtag of <choose> that follows <when> tags and runs only if all of the prior conditions evaluated to 'false'. |
<c:import> | Retrieves an absolute or relative URL and exposes its contents to either the page, a String in 'var', or a Reader in 'varReader'. |
<c:forEach > | The basic iteration tag, accepting many different collection types and supporting subsetting and other functionality . |
<c:forTokens> | Iterates over tokens, separated by the supplied delimeters. |
<c:param> | Adds a parameter to a containing 'import' tag's URL. |
<c:redirect > | Redirects to a new URL. |
<c:url> | Creates a URL with optional query parameters |
格式化标签:
使用JSTL格式标签来格式化和显示文本,日期,时间和数字的,国际化的网站。以下是在您的JSP的语法,包括格式化库:
<%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt" %>
以下是格式化JSTL标签列表:
Tag | Description |
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<fmt:formatNumber> | To render numerical value with specific precision or format. |
<fmt:parseNumber> | Parses the string representation of a number, currency, or percentage. |
<fmt:formatDate> | Formats a date and/or time using the supplied styles and pattern |
<fmt:parseDate> | Parses the string representation of a date and/or time |
<fmt:bundle> | Loads a resource bundle to be used by its tag body. |
<fmt:setLocale> | Stores the given locale in the locale configuration variable. |
<fmt:setBundle> | Loads a resource bundle and stores it in the named scoped variable or the bundle configuration variable. |
<fmt:timeZone> | Specifies the time zone for any time formatting or parsing actions nested in its body. |
<fmt:setTimeZone> | Stores the given time zone in the time zone configuration variable |
<fmt:message> | To display an internationalized message. |
<fmt:requestEncoding> | Sets the request character encoding |
SQL标签:
JSTL的SQL标签库标签可以交互关系型数据库(如Oracle,MySQL或Microsoft SQL Server的关系数据库管理系统)。
以下是在您的JSP语法包括JSTL SQL库:
<%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql" %>
以下是SQL JSTL标签的列表:
Tag | Description |
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<sql:setDataSource> | Creates a simple DataSource suitable only for prototyping |
<sql:query> | Executes the SQL query defined in its body or through the sql attribute. |
<sql:update> | Executes the SQL update defined in its body or through the sql attribute. |
<sql:param> | Sets a parameter in an SQL statement to the specified value. |
<sql:dateParam> | Sets a parameter in an SQL statement to the specified java.util.Date value. |
<sql:transaction > | Provides nested database action elements with a shared Connection, set up to execute all statements as one transaction. |
XML 标签:
JSTL XML标记提供了一种创建和操作XML文档的JSP为中心的方式。以下是在您的JSP的语法包括JSTL XML库。
JSTL XML标记库具有自定义标签与XML数据交互。这包括XML解析,转换XML数据,流控制,基于XPath表达式。
<%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml" %>
在继续之前的例子中,将需要复制下面的两个XML和XPath相关的库到<Tomcat安装目录> 的\lib目录:
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XercesImpl.jar: 下载地址 http://www.apache.org/dist/xerces/j/
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xalan.jar: 下载地址 http://xml.apache.org/xalan-j/index.html
以下是XML JSTL标签列表:
Tag | Description |
---|---|
<x:out> | Like <%= ... >, but for XPath expressions. |
<x:parse> | Use to parse XML data specified either via an attribute or in the tag body. |
<x:set > | Sets a variable to the value of an XPath expression. |
<x:if > | Evaluates a test XPath expression and if it is true, it processes its body. If the test condition is false, the body is ignored. |
<x:forEach> | To loop over nodes in an XML document. |
<x:choose> | Simple conditional tag that establishes a context for mutually exclusive conditional operations, marked by <when> and <otherwise> |
<x:when > | Subtag of <choose> that includes its body if its expression evalutes to 'true' |
<x:otherwise > | Subtag of <choose> that follows <when> tags and runs only if all of the prior conditions evaluated to 'false' |
<x:transform > | Applies an XSL transformation on a XML document |
<x:param > | Use along with the transform tag to set a parameter in the XSLT stylesheet |
JSTL 函数:
JSTL包括一些标准功能,其中大部分是常见的字符串操作函数。以下是在JSP的语法包函JSTL函数库:
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
以下是JSTL函数列表:
Function | Description |
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fn:contains() | Tests if an input string contains the specified substring. |
fn:containsIgnoreCase() | Tests if an input string contains the specified substring in a case insensitive way. |
fn:endsWith() | Tests if an input string ends with the specified suffix. |
fn:escapeXml() | Escapes characters that could be interpreted as XML markup. |
fn:indexOf() | Returns the index withing a string of the first occurrence of a specified substring. |
fn:join() | Joins all elements of an array into a string. |
fn:length() | Returns the number of items in a collection, or the number of characters in a string. |
fn:replace() | Returns a string resulting from replacing in an input string all occurrences with a given string. |
fn:split() | Splits a string into an array of substrings. |
fn:startsWith() | Tests if an input string starts with the specified prefix. |
fn:substring() | Returns a subset of a string. |
fn:substringAfter() | Returns a subset of a string following a specific substring. |
fn:substringBefore() | Returns a subset of a string before a specific substring. |
fn:toLowerCase() | Converts all of the characters of a string to lower case. |
fn:toUpperCase() | Converts all of the characters of a string to upper case. |
fn:trim() | Removes white spaces from both ends of a string. |