[Application] Sixth JSTL Custom Function tag Library

The function tag Library has been explained in the previous JSTL's summary, and I'll rearrange it once again!

Introduction to the self-brought function tag library

The way to introduce this tag library is:
<%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>

Name of function	function Description	Examples of Use
fn:contains	Determine if a string contains another string	<c:if test="${fn:contains(name, searchString)}">
fn:containsIgnoreCase	Determines whether a string contains another string (case-insensitive)	<c:if test="${fn:containsIgnoreCase(name, searchString)}">
fn:endsWith	Determines whether a string ends with a different string	<c:if test="${fn:endsWith(filename, ".txt")}">
fn:escapeXml	Turn some characters into XML representations, such as < characters that should be converted to&lt;	${fn:escapeXml(param:info)}
fn:indexOf	The position where the substring appears in the parent string	${fn:indexOf(name, "-")}
fn:join	Unites the data in the array into a new string and uses the specified character format to open the	${fn:join(array, ";")}
fn:length	gets the length of the string, or the size of the array	${fn:length(shoppingCart.products)}
fn:replace	Replace the character specified in the string	${fn:replace(text, "-", "&#149;")}
fn:split	Segmentation the string according to the specified word	${fn:split(customerNames, ";")}
fn:startsWith	Determines whether a string starts with a substring	<c:if test="${fn:startsWith(product.id, "100-")}">
fn:substring	Intercept sub-strings	${fn:substring(zip, 6, -1)}
fn:substringAfter	Gets the substring starting at the location of a character	${fn:substringAfter(zip, "-")}
fn:substringBefore	Gets the substring from the beginning to the location of a character	${fn:substringBefore(zip, "-")}
fn:toLowerCase	Convert to lowercase	${fn.toLowerCase(product.name)}
fn:toUpperCase	Convert to uppercase	${fn.UpperCase(product.name)}
fn:trim	Remove spaces before and after a string	${fn.trim(name)}

Explain

• Fn:contains (string, substring) returns true if the argument string contains a parameter substring
• Fn:containsignorecase (string, substring) returns true if the argument string contains a parameter substring (ignoring case)
• Fn:endswith (string, suffix) returns true if the argument string ends with the argument suffix
• Fn:escapexml (String) converts XML (and HTML) with special meaning to the corresponding XML character entity code, and returns
• Fn:indexof (string, substring) returns the position of the first occurrence of the parameter substring in the parameter string
• Fn:join (array, separator) strings a given array of arrays together with the given spacer separator, forming a new string and returning it.
• Fn:length (item) returns the number of elements contained in the parameter item. The parameter item type is an array, a collection, or a string. If it is of type string, the return value is the number of characters in string.
• Fn:replace (String, before, after) returns a String object. Replaces all occurrences of a parameter before string in a parameter string with a parameter after string, and returns the replaced result
• Fn:split (string, separator) returns an array that splits the argument string with the parameter separator, and each part of the split is an element of the array
• Fn:startswith (string, prefix) if the argument string starts with the argument prefix, returns true
• Fn:substring (string, begin, end) returns the string of the argument string, starting with the argument begin to the argument end position, including the character of the end position
• Fn:substringafter (string, substring) returns the argument substring the part of the string that follows the argument string
• Fn:substringbefore (string, substring) returns the part of the string that precedes the argument substring in the argument string
• Fn:tolowercase (string) turns all the characters in the argument string to lowercase and returns
• Fn:touppercase (string) converts all characters of the argument string to uppercase and returns it
• Fn:trim (string) strips the trailing and trailing spaces of the parameter string and returns

Custom Function Libraries The first step is to customize the class and method (public +static)

2. package com.pangsir.ty;
4. publicclassTestFunction{
6. /**
8. *
10. * 自定义类和方法 ，方法必须是public + static
12. * @param name
14. * @return
16. */
18. publicstaticString toTest(String name){
20. return"练习自定义函数, "+name;
22. }
24. }

Note: Totest () must be public static .

The second step is to write the custom tldFile, place this custom TLD file in the WEB-INFOr WEB-INF的任意子目录Under

2. <?xml version="1.0" encoding="UTF-8"?>
6. <taglibxmlns="http://java.sun.com/xml/ns/j2ee"
8. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
10. xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
12. version="2.0">
14. <!--该文件主要是受这个的影响:http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd -->
20. <description>test own defined functions library</description>
22. <display-name>test functions</display-name>
24. <!-- 定义的版本 -->
26. <tlib-version>1.0</tlib-version>
28. <!--这个名字可以随便取，尽量与文件名相同，这样我们知道文件在哪儿 -->
30. <short-name>test</short-name>
32. <!-- 这个地址是随便取得。到时候jsp页面引入这个地址 -->
34. <uri>http://codemihong.com/functions</uri>
36. <!-- 定义函数 -->
38. <function>
40. <!-- 自定义函数名称(随意) -->
42. <name>testFunction</name>
44. <!-- 定义函数的类全名称 -->
46. <function-class>com.pangsir.ty.TestFunction</function-class>
48. <!--java.lang.String：返回值类型 toTest：类定义的函数名(形参的数据类型) -->
50. <function-signature>java.lang.String toTest(java.lang.String)</function-signature>
52. </function>
54. </taglib>

Description

1. <description>、<description-name>、<tlib-version>、<short-name>、<uri>the label content is 注意这里设置的uri后面jsp中要引入 arbitrary,.
2. <function>tags in the tag <name> in the JSP to be called as function name, where the name can be consistent with the actual function name, can also be inconsistent, can be considered an alias of the actual function name.
3. <function-class>The tag is the package name + Class name (custom Class).
4. <function-signature>is a description of the custom function, if it is a wrapper type, write the full path, or if it is the base data type, it is not required . This is shown in another example:

2. <function>
4. <description>
6. Returns the index withing a string of the first occurrence of a specified substring.
8. </description>
10. <name>indexOf</name>
12. <function-class>org.apache.taglibs.standard.functions.Functions</function-class>
14. <function-signature>int indexOf(java.lang.String, java.lang.String)</function-signature>
16. <example>
18. ${fn:indexOf(name, "-")}
20. </example>
22. </function>

补充说明:Register the JSTL function, and if the URI is/web-inf/xxx.tld, you do not need to register the following Tomcat

1. <!-- 注册JSTL函数 -->
2. <jsp-config>
3. <taglib>
4. <taglib-uri>http://codemihong.com/functions</taglib-uri>
5. <taglib-location>/WEB-INF/myfunctions.tld</taglib-location>
6. </taglib>
7. </jsp-config>

The third step is to introduce a JSP page in which you want to use your custom function library

<%@ taglib prefix="hp" uri="http://codemihong.com/functions" %>

The fourth step uses: ${prefix + colon + function alias}

1. <body>
2. 测试JSTL--自定义函数库
3. <spanstyle="color:#006600;"></span> ${hp:testFunction("人总是需要向前看的") }
4. </body>

Fifth Step Test

[Application] Sixth JSTL Custom Function tag Library