Writing the Tag Library Descriptor
Writing the Tag Library Descriptor
protected ValueExpression formatPatterns = null;
public void setFormatPatterns(ValueExpression fmtPatterns){
formatPatterns = fmtPatterns;
}
Finally, the createValidator method creates an instance of FormatValidator, extracts the
value from the formatPatterns attribute's value expression and sets the formatPatterns
property of FormatValidator to this value:
the formatPatterns property of FormatValidator to this value:
protected Validator createValidator() throws JspException {
FacesContext facesContext =
FacesContext.getCurrentInstance();
FormatValidator result = null;
if(validatorID != null){
result = (FormatValidator) facesContext.getApplication()
.createValidator(validatorID);
}
String patterns = null;
if (formatPatterns != null) {
if (!formatPatterns.isLiteralText()) {
patterns = (String)
formatPatterns.getValue(facesContext.getELContext());
} else {
patterns = formatPatterns.getExpressionString();
}
Writing the Tag Library Descriptor
To define a tag, you declare it in a tag library descriptor (TLD), which is an XML document that
describes a tag library. A TLD contains information about a library and each tag contained in it.
See
for more information about TLDs.
The custom validator tag is defined in bookstore.tld, located in the
tut-install/javaeetutorial5/examples/web/bookstore6/web/WEB-INF/ directory. It
contains a tag definition for formatValidator:
<tag>
<name>formatValidator</name>
...
<tag-class>
com.sun.bookstore6.taglib.FormatValidatorTag</tag-class>
<attribute>
<name>formatPatterns</name>
<required>true</required>
<deferred-value>
Creating a Custom Validator
Chapter 12 · Developing with JavaServer Faces Technology
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