I want to capture the base path of a given url
http://mydomain.com/mypath/coolpath/favoritepath/file.htm
so basically i just want this:
/mypath/coolpath/favoritepath/
Any ideas how to do this without using straight Java?
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1 Answer
This functionality doesn't exist in JSTL. Closest is the fn:replace(), but it doesn't support regular expressions. The other functions provides the possibility to get rid of the leading part until with the domain (using fn:substringAfter() a several times on // and /), but there's nothing which makes it easy to get rid of the trailing part. Maybe with a whole bunch of fn:substringAfter and c:set in a loop, but it would make the code clumsy and not really reuseable.
Well, in regex you could use ^[^/]+/+[^/]+|[^/]+$ for this:
url = url.replaceAll("^[^/]+/+[^/]+|[^/]+$", "");
You could create a custom EL function which does exactly this:
${f:replaceAll(url, '^[^/]+/+[^/]+|[^/]+$', '')}
To achieve this, first create a class like this:
package com.example;
public final class Functions {
private Functions() {}
public static String replaceAll(String string, String pattern, String replacement) {
return string.replaceAll(pattern, replacement);
}
}
and create a /WEB-INF/functions.tld like this:
<?xml version="1.0" encoding="UTF-8" ?>
<taglib
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
version="2.1">
<display-name>Custom Functions</display-name>
<tlib-version>1.0</tlib-version>
<uri>http://example.com/functions</uri>
<function>
<name>matches</name>
<function-class>com.example.Functions</function-class>
<function-signature>java.lang.String replaceAll(java.lang.String, java.lang.String, java.lang.String)</function-signature>
</function>
</taglib>
which you can import as:
<%@taglib uri="http://example.com/functions" prefix="f" %>
2 Comments
Bozho
Won't it be nicer to use java.sun.com/javase/6/docs/api/java/net/URL.html and getProtocol(), getHost(), etc ?
BalusC
@Bozho: that was also the first where I looked, but it doesn't have methods to return exactly the desired string. The
getPath() comes close, but you would still need to substring/replace the last part off. Also, constructing an URL is a bit more expensive. So I thought, let's give an generic example with String#replaceAll(), which may have more uses than this.