/*
* $Id: ConverterTag.java,v 1.25 2007/04/27 22:00:11 ofung Exp $
*/
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package javax.faces.webapp;
import javax.el.ValueExpression;
import javax.faces.component.UIComponent;
import javax.faces.component.ValueHolder;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.ConverterException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
/**
* <p><strong>ConverterTag</strong> is a base class for all JSP custom actions
* that create and register a <code>Converter</code> instance on the
* {@link ValueHolder} associated with our most immediate
* surrounding instance of a tag whose implementation class is a subclass
* of {@link UIComponentTag}. To avoid creating duplicate instances when
* a page is redisplayed, creation and registration of a {@link Converter}
* occurs <strong>only</strong> if the corresponding {@link UIComponent} was
* created (by the owning {@link UIComponentTag}) during the execution of the
* current page.</p>
*
* <p>This class may be used directly to implement a generic converter
* registration tag (based on the converter-id specified by the
* <code>converterId</code> attribute), or as a base class for tag
* instances that support specific {@link Converter} subclasses. This
* <code>converterId</code> attribute must refer to one of the well
* known converter-ids, or a custom converter-id as defined in a
* <code>faces-config.xml</code> file.</p>
*
* <p>Subclasses of this class must implement the
* <code>createConverter()</code> method, which creates and returns a
* {@link Converter} instance. Any configuration properties that specify
* behavior of this {@link Converter} must have been set by the
* <code>createConverter()</code> method. Generally, this occurs
* by copying corresponding attribute values on the tag instance.</p>
*
* <p>This tag creates no output to the page currently being created. It
* is used solely for the side effect of {@link Converter} creation.</p>
*
* @deprecated This has been partially replaced by {@link
* ConverterELTag}. The remainder of the functionality, namely, the
* binding facility and the implementation of the {@link
* #createConverter} method, is now an implementation detail.
*/
public class ConverterTag extends TagSupport {
// ---------------------------------------------------------- Static Members
private static final long serialVersionUID = -5909792518081427720L;
// -------------------------------------------------------------- Attributes
/**
* <p>The identifier of the {@link Converter} instance to be created.</p>
*/
private String converterId = null;
/**
* <p>The {@link ValueExpression} that evaluates to an object that
* implements {@link Converter}.</p>
*/
private String binding = null;
/**
* <p>Set the identifer of the {@link Converter} instance to be created.
*
* @param converterId The identifier of the converter instance to be
* created.
*/
public void setConverterId(String converterId) {
this.converterId = converterId;
}
/**
* <p>Set the expression that will be used to create a {@link ValueExpression}
* that references a backing bean property of the {@link Converter} instance to
* be created.</p>
*
* @param binding The new expression
*
* @throws JspException if a JSP error occurs
*/
public void setBinding(String binding)
throws JspException {
if (binding!= null && !UIComponentTag.isValueReference(binding)) {
// PENDING i18n
throw new JspException("Invalid Expression:"+binding);
}
this.binding = binding;
}
// ---------------------------------------------------------- Public Methods
/**
* <p>Create a new instance of the specified {@link Converter}
* class, and register it with the {@link UIComponent} instance associated
* with our most immediately surrounding {@link UIComponentTag} instance, if
* the {@link UIComponent} instance was created by this execution of the
* containing JSP page. If the localValue of the
* {@link UIComponent} is a String, attempt to convert it.</p>
*
* @throws JspException if a JSP error occurs
*/
public int doStartTag() throws JspException {
// Locate our parent UIComponentTag
UIComponentClassicTagBase tag =
UIComponentClassicTagBase.getParentUIComponentClassicTagBase(pageContext);
if (tag == null) { // PENDING - i18n
throw new JspException("Not nested in a UIComponentTag Error for tag with handler class:"+
this.getClass().getName());
}
// Nothing to do unless this tag created a component
if (!tag.getCreated()) {
return (SKIP_BODY);
}
UIComponent component = tag.getComponentInstance();
if (component == null) {
//PENDING i18n
throw new JspException("Can't create Component from tag.");
}
if (!(component instanceof ValueHolder)) {
//PENDING i18n
throw new JspException("Not nested in a tag of proper type. Error for tag with handler class:"+
this.getClass().getName());
}
Converter converter = createConverter();
if (converter == null) {
//noinspection NonConstantStringShouldBeStringBuffer
String converterError = null;
if (binding != null) {
converterError = binding;
}
if (converterId != null) {
if (converterError != null) {
converterError += " or " + converterId;
} else {
converterError = converterId;
}
}
// PENDING i18n
throw new JspException("Can't create class of type:"+
"javax.faces.convert.Converter for:"+converterError);
}
ValueHolder vh = (ValueHolder)component;
FacesContext context = FacesContext.getCurrentInstance();
// Register an instance with the appropriate component
vh.setConverter(converter);
// Once the converter has been set, attempt to convert the
// incoming "value"
Object localValue = vh.getLocalValue();
if (localValue instanceof String) {
try {
localValue = converter.getAsObject(context, (UIComponent)vh, (String) localValue);
vh.setValue(localValue);
}
catch (ConverterException ce) {
// PENDING - Ignore? Throw an exception? Set the local
// value back to "null" and log a warning?
}
}
return (SKIP_BODY);
}
/**
* <p>Release references to any acquired resources.
*/
public void release() {
this.converterId = null;
}
// ------------------------------------------------------- Protected Methods
/**
* <p>Create and return a new {@link Converter} to be registered
* on our surrounding {@link UIComponent}.</p>
*
* @throws JspException if a new instance cannot be created
*/
protected Converter createConverter()
throws JspException {
FacesContext context = FacesContext.getCurrentInstance();
Converter converter = null;
ValueExpression vb = null;
// If "binding" is set, use it to create a converter instance.
if (binding != null) {
try {
vb =
context.getApplication().getExpressionFactory().createValueExpression(context.getELContext(), binding, Object.class);
if (vb != null) {
converter = (Converter)vb.getValue(context.getELContext());
if (converter != null) {
return converter;
}
}
} catch (Exception e) {
throw new JspException(e);
}
}
// If "converterId" is set, use it to create the converter
// instance. If "converterId" and "binding" are both set, store the
// converter instance in the value of the property represented by
// the value binding expression.
if (converterId != null) {
try {
String converterIdVal = converterId;
if (UIComponentTag.isValueReference(converterId)) {
ValueExpression idBinding =
context.getApplication().getExpressionFactory().createValueExpression(context.getELContext(), converterId, Object.class);
converterIdVal = (String) idBinding.getValue(context.getELContext());
}
converter = context.getApplication().createConverter(converterIdVal);
if (converter != null) {
if (vb != null) {
vb.setValue(context.getELContext(), converter);
}
}
} catch (Exception e) {
throw new JspException(e);
}
}
return converter;
}
}