JSP之JSTL_functions

  1 <?xml version="1.0" encoding="UTF-8" ?>
  2 
  3 <taglib xmlns="http://java.sun.com/xml/ns/j2ee"
  4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  5 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
  6 version="2.0">
  7     
  8 <description>JSTL 1.1 functions library</description>
  9 <display-name>JSTL functions</display-name>
 10 <tlib-version>1.1</tlib-version>
 11 <short-name>fn</short-name>
 12 <uri>http://java.sun.com/jsp/jstl/functions</uri>
 13 
 14 <function>
 15 <description>
 16       Tests if an input string contains the specified substring.
 17 </description>
 18 <name>contains</name>
 19 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 20 <function-signature>boolean contains(java.lang.String, java.lang.String)</function-signature>
 21 <example>
 22 &lt;c:if test="${fn:contains(name, searchString)}">
 23 </example>
 24 </function>
 25 
 26 <function>
 27 <description>
 28       Tests if an input string contains the specified substring in a case insensitive way.
 29 </description>
 30 <name>containsIgnoreCase</name>
 31 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 32 <function-signature>boolean containsIgnoreCase(java.lang.String, java.lang.String)</function-signature>
 33 <example>
 34 &lt;c:if test="${fn:containsIgnoreCase(name, searchString)}">
 35 </example>
 36 </function>
 37 
 38 <function>
 39 <description>
 40       Tests if an input string ends with the specified suffix.
 41 </description>
 42 <name>endsWith</name>
 43 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 44 <function-signature>boolean endsWith(java.lang.String, java.lang.String)</function-signature>
 45 <example>
 46 &lt;c:if test="${fn:endsWith(filename, ".txt")}">
 47 </example>
 48 </function>
 49 
 50 <function>
 51 <description>
 52       Escapes characters that could be interpreted as XML markup.
 53 </description>
 54 <name>escapeXml</name>
 55 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 56 <function-signature>java.lang.String escapeXml(java.lang.String)</function-signature>
 57 <example>
 58       ${fn:escapeXml(param:info)}
 59 </example>
 60 </function>
 61 
 62 <function>
 63 <description>
 64       Returns the index withing a string of the first occurrence of a specified substring.
 65 </description>
 66 <name>indexOf</name>
 67 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 68 <function-signature>int indexOf(java.lang.String, java.lang.String)</function-signature>
 69 <example>
 70       ${fn:indexOf(name, "-")}
 71 </example>
 72 </function>
 73 
 74 <function>
 75 <description>
 76       Joins all elements of an array into a string.
 77 </description>
 78 <name>join</name>
 79 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 80 <function-signature>java.lang.String join(java.lang.String[], java.lang.String)</function-signature>
 81 <example>
 82       ${fn:join(array, ";")}
 83 </example>
 84 </function>
 85 
 86 <function>
 87 <description>
 88       Returns the number of items in a collection, or the number of characters in a string.
 89 </description>
 90 <name>length</name>
 91 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
 92 <function-signature>int length(java.lang.Object)</function-signature>
 93 <example>
 94       You have ${fn:length(shoppingCart.products)} in your shopping cart.
 95 </example>
 96 </function>
 97 
 98 <function>
 99 <description>
100       Returns a string resulting from replacing in an input string all occurrences
101       of a "before" string into an "after" substring.
102 </description>
103 <name>replace</name>
104 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
105 <function-signature>java.lang.String replace(java.lang.String, java.lang.String, java.lang.String)</function-signature>
106 <example>
107       ${fn:replace(text, "-", "&#149;")}
108 </example>
109 </function>
110 
111 <function>
112 <description>
113       Splits a string into an array of substrings.
114 </description>
115 <name>split</name>
116 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
117 <function-signature>java.lang.String[] split(java.lang.String, java.lang.String)</function-signature>
118 <example>
119       ${fn:split(customerNames, ";")}
120 </example>
121 </function>
122 
123 <function>
124 <description>
125       Tests if an input string starts with the specified prefix.
126 </description>
127 <name>startsWith</name>
128 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
129 <function-signature>boolean startsWith(java.lang.String, java.lang.String)</function-signature>
130 <example>
131 &lt;c:if test="${fn:startsWith(product.id, "100-")}">
132 </example>
133 </function>
134 
135 <function>
136 <description>
137       Returns a subset of a string.
138 </description>
139 <name>substring</name>
140 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
141 <function-signature>java.lang.String substring(java.lang.String, int, int)</function-signature>
142 <example>
143       P.O. Box: ${fn:substring(zip, 6, -1)}
144 </example>
145 </function>
146 
147 <function>
148 <description>
149       Returns a subset of a string following a specific substring.
150 </description>
151 <name>substringAfter</name>
152 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
153 <function-signature>java.lang.String substringAfter(java.lang.String, java.lang.String)</function-signature>
154 <example>
155       P.O. Box: ${fn:substringAfter(zip, "-")}
156 </example>
157 </function>
158 
159 <function>
160 <description>
161       Returns a subset of a string before a specific substring.
162 </description>
163 <name>substringBefore</name>
164 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
165 <function-signature>java.lang.String substringBefore(java.lang.String, java.lang.String)</function-signature>
166 <example>
167       Zip (without P.O. Box): ${fn:substringBefore(zip, "-")}
168 </example>
169 </function>
170 
171 <function>
172 <description>
173       Converts all of the characters of a string to lower case.
174 </description>
175 <name>toLowerCase</name>
176 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
177 <function-signature>java.lang.String toLowerCase(java.lang.String)</function-signature>
178 <example>
179       Product name: ${fn:toLowerCase(product.name)}
180 </example>
181 </function>
182 
183 <function>
184 <description>
185       Converts all of the characters of a string to upper case.
186 </description>
187 <name>toUpperCase</name>
188 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
189 <function-signature>java.lang.String toUpperCase(java.lang.String)</function-signature>
190 <example>
191       Product name: ${fn:UpperCase(product.name)}
192 </example>
193 </function>
194 
195 <function>
196 <description>
197       Removes white spaces from both ends of a string.
198 </description>
199 <name>trim</name>
200 <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
201 <function-signature>java.lang.String trim(java.lang.String)</function-signature>
202 <example>
203       Name: ${fn:trim(name)}
204 </example> 
205 </function>
206 
207 </taglib>
复制代码

上述是http://java.sun.com/jsp/jstl/functions的源代码

用来弥补JSTL在处理字符串上的缺陷

使用的方式

一、

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

二、

在WEB-INF目录下创建functions.ltd

然后将上述代码拷进去

<%@ taglib prefix="fn" uri="/WEB-INF/functions.tld" %>

或则

<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

区别在于说这样的话即使不联网也可以使用

<!-- 函数说明 -->

函数名函数说明使用举例
fn:contains判断字符串是否包含另外一个字符串<c:if test="${fn:contains(name, searchString)}">
fn:containsIgnoreCase判断字符串是否包含另外一个字符串(大小写无关)<c:if test="${fn:containsIgnoreCase(name, searchString)}">
fn:endsWith判断字符串是否以另外字符串结束<c:if test="${fn:endsWith(filename, ".txt")}">
fn:escapeXml把一些字符转成XML表示,例如<字符应该转为&lt;${fn:escapeXml(param:info)}
fn:indexOf子字符串在母字符串中出现的位置${fn:indexOf(name, "-")}
fn:join将数组中的数据联合成一个新字符串,并使用指定字符格开${fn:join(array, ";")}
fn:length获取字符串的长度,或者数组的大小${fn:length(shoppingCart.products)}
fn:replace替换字符串中指定的字符${fn:replace(text, "-", "&#149;")}
fn:split把字符串按照指定字符切分${fn:split(customerNames, ";")}
fn:startsWith判断字符串是否以某个子串开始<c:if test="${fn:startsWith(product.id, "100-")}">
fn:substring获取子串${fn:substring(zip, 6, -1)}
fn:substringAfter

获取从某个字符所在位置开始的子串

${fn:substringAfter(zip, "-")}
fn:substringBefore获取从开始到某个字符所在位置的子串${fn:substringBefore(zip, "-")}
fn:toLowerCase转为小写${fn.toLowerCase(product.name)}
fn:toUpperCase转为大写字符${fn.UpperCase(product.name)}
fn:trim去除字符串前后的空格${fn.trim(name)}


其实就是一些JAVA中处理字符串的方法。

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