public class

UrlTag

extends HtmlEscapingAwareTag
implements ParamAware
java.lang.Object
   ↳ TagSupport
     ↳ org.springframework.web.servlet.tags.RequestContextAwareTag
       ↳ org.springframework.web.servlet.tags.HtmlEscapingAwareTag
         ↳ org.springframework.web.servlet.tags.UrlTag

Class Overview

JSP tag for creating URLs. Modeled after the JSTL c:url tag with backwards compatibility in mind.

Enhancements to the JSTL functionality include:

  • URL encoded template URI variables
  • HTML/XML escaping of URLs
  • JavaScript escaping of URLs

Template URI variables are indicated in the 'value' attribute and marked by braces '{variableName}'. The braces and attribute name are replaced by the URL encoded value of a parameter defined with the spring:param tag in the body of the url tag. If no parameter is available the literal value is passed through. Params matched to template variables will not be added to the query string.

Use of the spring:param tag for URI template variables is strongly recommended over direct EL substitution as the values are URL encoded. Failure to properly encode URL can leave an application vulnerable to XSS and other injection attacks.

URLs can be HTML/XML escaped by setting the 'htmlEscape' attribute to 'true'. Detects an HTML escaping setting, either on this tag instance, the page level, or the web.xml level. The default is 'false'. When setting the URL value into a variable, escaping is not recommended.

Example usage: 

<spring:url value="/url/path/{variableName}">
   <spring:param name="variableName" value="more than JSTL c:url" />
 </spring:url>
Results in: /currentApplicationContext/url/path/more%20than%20JSTL%20c%3Aurl

See Also

Summary

[Expand]
Inherited Constants
From class org.springframework.web.servlet.tags.RequestContextAwareTag
[Expand]
Inherited Fields
From class org.springframework.web.servlet.tags.RequestContextAwareTag
Public Constructors
UrlTag()
Public Methods
void addParam(Param param)
Callback hook for nested spring:param tags to pass their value to the parent tag.
int doEndTag()
int doStartTagInternal()
Called by doStartTag to perform the actual work.
void setContext(String context)
Set the context path for the URL.
void setJavaScriptEscape(String javaScriptEscape)
Set JavaScript escaping for this tag, as boolean value.
void setScope(String scope)
Set the scope to export the URL variable to.
void setValue(String value)
Sets the value of the URL
void setVar(String var)
Set the variable name to expose the URL under.
Protected Methods
String createQueryString(List<Param> params, Set<String> usedParams, boolean includeQueryStringDelimiter)
Build the query string from available parameters that have not already been applied as template params.
String replaceUriTemplateParams(String uri, List<Param> params, Set<String> usedParams)
Replace template markers in the URL matching available parameters.
[Expand]
Inherited Methods
From class org.springframework.web.servlet.tags.HtmlEscapingAwareTag
From class org.springframework.web.servlet.tags.RequestContextAwareTag
From class java.lang.Object
From interface org.springframework.web.servlet.tags.ParamAware

Public Constructors

public UrlTag ()

Public Methods

public void addParam (Param param)

Callback hook for nested spring:param tags to pass their value to the parent tag.

Parameters
param the result of the nested spring:param tag

public int doEndTag ()

Throws
JspException

public int doStartTagInternal ()

Called by doStartTag to perform the actual work.

Returns
  • same as TagSupport.doStartTag
Throws
JspException

public void setContext (String context)

Set the context path for the URL. Defaults to the current context

public void setJavaScriptEscape (String javaScriptEscape)

Set JavaScript escaping for this tag, as boolean value. Default is "false".

Throws
JspException

public void setScope (String scope)

Set the scope to export the URL variable to. This attribute has no meaning unless var is also defined.

public void setValue (String value)

Sets the value of the URL

public void setVar (String var)

Set the variable name to expose the URL under. Defaults to rendering the URL to the current JspWriter

Protected Methods

protected String createQueryString (List<Param> params, Set<String> usedParams, boolean includeQueryStringDelimiter)

Build the query string from available parameters that have not already been applied as template params.

The names and values of parameters are URL encoded.

Parameters
params the parameters to build the query string from
usedParams set of parameter names that have been applied as template params
includeQueryStringDelimiter true if the query string should start with a '?' instead of '&'
Returns
  • the query string
Throws
JspException

protected String replaceUriTemplateParams (String uri, List<Param> params, Set<String> usedParams)

Replace template markers in the URL matching available parameters. The name of matched parameters are added to the used parameters set.

Parameter values are URL encoded.

Parameters
uri the URL with template parameters to replace
params parameters used to replace template markers
usedParams set of template parameter names that have been replaced
Returns
  • the URL with template parameters replaced
Throws
JspException