package org.springframework.webflow.expression.el;
import java.beans.FeatureDescriptor;
import java.util.Iterator;
import java.util.Locale;
import javax.el.ELContext;
import javax.el.ELResolver;
import javax.el.PropertyNotWritableException;
import org.springframework.context.MessageSource;
import org.springframework.webflow.execution.RequestContext;
import org.springframework.webflow.execution.RequestContextHolder;
/**
* Custom EL resolver that resolves the messages from the active flow's {@link MessageSource}. The message source is
* indexed under the key <code>resourceBundle</code>. To access a message, specify its key e.g.
* <code>resourceBundle.myMessage</code>.
*
* @author Jeremy Grelle
*/
public class FlowResourceELResolver extends ELResolver {
static final String RESOURCE_BUNDLE_KEY = "resourceBundle";
private RequestContext requestContext;
public FlowResourceELResolver() {
}
public FlowResourceELResolver(RequestContext requestContext) {
this.requestContext = requestContext;
}
public Class<?> getCommonPropertyType(ELContext context, Object base) {
if (base == null) {
return MessageSource.class;
} else if (base instanceof MessageSource) {
return String.class;
} else {
return null;
}
}
public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
return null;
}
public Class<?> getType(ELContext context, Object base, Object property) {
RequestContext requestContext = getRequestContext();
if (requestContext == null) {
return null;
}
if (base == null && RESOURCE_BUNDLE_KEY.equals(property)) {
context.setPropertyResolved(true);
return MessageSource.class;
} else if (base instanceof MessageSource) {
MessageSource messageSource = (MessageSource) base;
String message = messageSource.getMessage(property.toString(), null, null, getLocale());
if (message != null) {
context.setPropertyResolved(true);
return String.class;
}
}
return null;
}
public Object getValue(ELContext context, Object base, Object property) {
RequestContext requestContext = getRequestContext();
if (requestContext == null) {
return null;
}
if (base == null && RESOURCE_BUNDLE_KEY.equals(property)) {
context.setPropertyResolved(true);
return getMessageSource();
} else if (base instanceof MessageSource) {
MessageSource messageSource = (MessageSource) base;
String message = messageSource.getMessage(property.toString(), null, null, getLocale());
if (message != null) {
context.setPropertyResolved(true);
return message;
}
}
return null;
}
public boolean isReadOnly(ELContext context, Object base, Object property) {
RequestContext requestContext = getRequestContext();
if (requestContext == null) {
return false;
}
if (base == null && RESOURCE_BUNDLE_KEY.equals(property)) {
context.setPropertyResolved(true);
return true;
} else if (base instanceof MessageSource) {
context.setPropertyResolved(true);
return true;
}
return false;
}
public void setValue(ELContext context, Object base, Object property, Object value) {
RequestContext requestContext = getRequestContext();
if (requestContext == null) {
return;
}
if (base == null && RESOURCE_BUNDLE_KEY.equals(property)) {
throw new PropertyNotWritableException("The '" + RESOURCE_BUNDLE_KEY
+ "' implicit variable is not writable.");
} else if (base instanceof MessageSource) {
throw new PropertyNotWritableException("The flow's MessageSource is not writable.");
}
}
protected Locale getLocale() {
return getRequestContext().getExternalContext().getLocale();
}
protected MessageSource getMessageSource() {
return getRequestContext().getActiveFlow().getApplicationContext();
}
protected RequestContext getRequestContext() {
return requestContext != null ? requestContext : RequestContextHolder.getRequestContext();
}
}