org.springframework.web.servlet.tags
Class UrlTag

java.lang.Object
  extended by javax.servlet.jsp.tagext.TagSupport
      extended by org.springframework.web.servlet.tags.RequestContextAwareTag
          extended by org.springframework.web.servlet.tags.HtmlEscapingAwareTag
              extended by org.springframework.web.servlet.tags.UrlTag
All Implemented Interfaces:
Serializable, IterationTag, JspTag, Tag, TryCatchFinally, ParamAware

public class UrlTag
extends HtmlEscapingAwareTag
implements ParamAware

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

Enhancements to the JSTL functionality include:

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+than+JSTL+c%3Aurl

Since:
3.0
Author:
Scott Andrews
See Also:
ParamTag, Serialized Form

Field Summary
 
Fields inherited from class org.springframework.web.servlet.tags.RequestContextAwareTag
logger, REQUEST_CONTEXT_PAGE_ATTRIBUTE
 
Fields inherited from class javax.servlet.jsp.tagext.TagSupport
id, pageContext
 
Fields inherited from interface javax.servlet.jsp.tagext.IterationTag
EVAL_BODY_AGAIN
 
Fields inherited from interface javax.servlet.jsp.tagext.Tag
EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE
 
Constructor Summary
UrlTag()
           
 
Method Summary
 void addParam(Param param)
          Callback hook for nested spring:param tags to pass their value to the parent tag.
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.
 int doEndTag()
           
 int doStartTagInternal()
          Called by doStartTag to perform the actual work.
protected  String replaceUriTemplateParams(String uri, List<Param> params, Set<String> usedParams)
          Replace template markers in the URL matching available parameters.
 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  String urlEncode(String value)
          URL-encode the providedSstring using the character encoding for the response.
 
Methods inherited from class org.springframework.web.servlet.tags.HtmlEscapingAwareTag
isDefaultHtmlEscape, isHtmlEscape, setHtmlEscape
 
Methods inherited from class org.springframework.web.servlet.tags.RequestContextAwareTag
doCatch, doFinally, doStartTag, getRequestContext
 
Methods inherited from class javax.servlet.jsp.tagext.TagSupport
doAfterBody, findAncestorWithClass, getId, getParent, getValue, getValues, release, removeValue, setId, setPageContext, setParent, setValue
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

UrlTag

public UrlTag()
Method Detail

setValue

public void setValue(String value)
Sets the value of the URL


setContext

public void setContext(String context)
Set the context path for the URL. Defaults to the current context


setVar

public void setVar(String var)
Set the variable name to expose the URL under. Defaults to rendering the URL to the current JspWriter


setScope

public void setScope(String scope)
Set the scope to export the URL variable to. This attribute has no meaning unless var is also defined.


setJavaScriptEscape

public void setJavaScriptEscape(String javaScriptEscape)
                         throws JspException
Set JavaScript escaping for this tag, as boolean value. Default is "false".

Throws:
JspException

addParam

public void addParam(Param param)
Description copied from interface: ParamAware
Callback hook for nested spring:param tags to pass their value to the parent tag.

Specified by:
addParam in interface ParamAware
Parameters:
param - the result of the nested spring:param tag

doStartTagInternal

public int doStartTagInternal()
                       throws JspException
Description copied from class: RequestContextAwareTag
Called by doStartTag to perform the actual work.

Specified by:
doStartTagInternal in class RequestContextAwareTag
Returns:
same as TagSupport.doStartTag
Throws:
JspException
See Also:
TagSupport.doStartTag()

doEndTag

public int doEndTag()
             throws JspException
Specified by:
doEndTag in interface Tag
Overrides:
doEndTag in class TagSupport
Throws:
JspException

createQueryString

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

replaceUriTemplateParams

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

urlEncode

protected String urlEncode(String value)
                    throws JspException
URL-encode the providedSstring using the character encoding for the response.

Parameters:
value - the value to encode
Returns:
the URL encoded value
Throws:
JspException - if the character encoding is invalid