org.apache.taglibs.standard.tag.common.fmt.BundleSupport Maven / Gradle / Ivy
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package org.apache.taglibs.standard.tag.common.fmt;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.jstl.core.Config;
import javax.servlet.jsp.jstl.fmt.LocalizationContext;
import javax.servlet.jsp.tagext.BodyTagSupport;
import org.apache.taglibs.standard.tag.common.core.Util;
/**
* Support for tag handlers for <bundle>, the resource bundle loading
* tag in JSTL 1.0.
*
* @author Jan Luehe
*/
public abstract class BundleSupport extends BodyTagSupport {
//*********************************************************************
// Private constants
private static final Locale EMPTY_LOCALE = new Locale("", "");
//*********************************************************************
// Protected state
protected String basename; // 'basename' attribute
protected String prefix; // 'prefix' attribute
//*********************************************************************
// Private state
private LocalizationContext locCtxt;
//*********************************************************************
// Constructor and initialization
public BundleSupport() {
super();
init();
}
private void init() {
basename = prefix = null;
locCtxt = null;
}
//*********************************************************************
// Collaboration with subtags
public LocalizationContext getLocalizationContext() {
return locCtxt;
}
public String getPrefix() {
return prefix;
}
//*********************************************************************
// Tag logic
public int doStartTag() throws JspException {
locCtxt = getLocalizationContext(pageContext, basename);
return EVAL_BODY_BUFFERED;
}
public int doEndTag() throws JspException {
if (bodyContent != null) {
try {
pageContext.getOut().print(bodyContent.getString());
} catch (IOException ioe) {
throw new JspTagException(ioe.toString(), ioe);
}
}
return EVAL_PAGE;
}
// Releases any resources we may have (or inherit)
public void release() {
init();
}
//*********************************************************************
// Public utility methods
/**
* Gets the default I18N localization context.
*
* @param pc Page in which to look up the default I18N localization context
*/
public static LocalizationContext getLocalizationContext(PageContext pc) {
LocalizationContext locCtxt = null;
Object obj = Config.find(pc, Config.FMT_LOCALIZATION_CONTEXT);
if (obj == null) {
return null;
}
if (obj instanceof LocalizationContext) {
locCtxt = (LocalizationContext) obj;
} else {
// localization context is a bundle basename
locCtxt = getLocalizationContext(pc, (String) obj);
}
return locCtxt;
}
/**
* Gets the resource bundle with the given base name, whose locale is
* determined as follows:
*
* Check if a match exists between the ordered set of preferred
* locales and the available locales, for the given base name.
* The set of preferred locales consists of a single locale
* (if the javax.servlet.jsp.jstl.fmt.locale configuration
* setting is present) or is equal to the client's preferred locales
* determined from the client's browser settings.
*
* If no match was found in the previous step, check if a match
* exists between the fallback locale (given by the
* javax.servlet.jsp.jstl.fmt.fallbackLocale configuration
* setting) and the available locales, for the given base name.
*
* @param pageContext Page in which the resource bundle with the
* given base name is requested
* @param basename Resource bundle base name
*
* @return Localization context containing the resource bundle with the
* given base name and the locale that led to the resource bundle match,
* or the empty localization context if no resource bundle match was found
*/
public static LocalizationContext getLocalizationContext(PageContext pc,
String basename) {
LocalizationContext locCtxt = null;
ResourceBundle bundle = null;
if ((basename == null) || basename.equals("")) {
return new LocalizationContext();
}
// Try preferred locales
Locale pref = SetLocaleSupport.getLocale(pc, Config.FMT_LOCALE);
if (pref != null) {
// Preferred locale is application-based
bundle = findMatch(basename, pref);
if (bundle != null) {
locCtxt = new LocalizationContext(bundle, pref);
}
} else {
// Preferred locales are browser-based
locCtxt = findMatch(pc, basename);
}
if (locCtxt == null) {
// No match found with preferred locales, try using fallback locale
pref = SetLocaleSupport.getLocale(pc, Config.FMT_FALLBACK_LOCALE);
if (pref != null) {
bundle = findMatch(basename, pref);
if (bundle != null) {
locCtxt = new LocalizationContext(bundle, pref);
}
}
}
if (locCtxt == null) {
// try using the root resource bundle with the given basename
try {
bundle = ResourceBundle.getBundle(basename, EMPTY_LOCALE,
Thread.currentThread().getContextClassLoader());
if (bundle != null) {
locCtxt = new LocalizationContext(bundle, null);
}
} catch (MissingResourceException mre) {
// do nothing
}
}
if (locCtxt != null) {
// set response locale
if (locCtxt.getLocale() != null) {
SetLocaleSupport.setResponseLocale(pc, locCtxt.getLocale());
}
} else {
// create empty localization context
locCtxt = new LocalizationContext();
}
return locCtxt;
}
//*********************************************************************
// Private utility methods
/*
* Determines the client's preferred locales from the request, and compares
* each of the locales (in order of preference) against the available
* locales in order to determine the best matching locale.
*
* @param pageContext the page in which the resource bundle with the
* given base name is requested
* @param basename the resource bundle's base name
*
* @return the localization context containing the resource bundle with
* the given base name and best matching locale, or null if no
* resource bundle match was found
*/
private static LocalizationContext findMatch(PageContext pageContext,
String basename) {
LocalizationContext locCtxt = null;
// Determine locale from client's browser settings.
for (Enumeration enum_ = Util.getRequestLocales((HttpServletRequest)pageContext.getRequest());
enum_.hasMoreElements(); ) {
Locale pref = (Locale) enum_.nextElement();
ResourceBundle match = findMatch(basename, pref);
if (match != null) {
locCtxt = new LocalizationContext(match, pref);
break;
}
}
return locCtxt;
}
/*
* Gets the resource bundle with the given base name and preferred locale.
*
* This method calls java.util.ResourceBundle.getBundle(), but ignores
* its return value unless its locale represents an exact or language match
* with the given preferred locale.
*
* @param basename the resource bundle base name
* @param pref the preferred locale
*
* @return the requested resource bundle, or null if no resource
* bundle with the given base name exists or if there is no exact- or
* language-match between the preferred locale and the locale of
* the bundle returned by java.util.ResourceBundle.getBundle().
*/
private static ResourceBundle findMatch(String basename, Locale pref) {
ResourceBundle match = null;
try {
ResourceBundle bundle =
ResourceBundle.getBundle(basename, pref,
Thread.currentThread().getContextClassLoader());
Locale avail = bundle.getLocale();
if (pref.equals(avail)) {
// Exact match
match = bundle;
} else {
/*
* We have to make sure that the match we got is for
* the specified locale. The way ResourceBundle.getBundle()
* works, if a match is not found with (1) the specified locale,
* it tries to match with (2) the current default locale as
* returned by Locale.getDefault() or (3) the root resource
* bundle (basename).
* We must ignore any match that could have worked with (2) or (3).
* So if an exact match is not found, we make the following extra
* tests:
* - avail locale must be equal to preferred locale
* - avail country must be empty or equal to preferred country
* (the equality match might have failed on the variant)
*/
if (pref.getLanguage().equals(avail.getLanguage())
&& ("".equals(avail.getCountry()) || pref.getCountry().equals(avail.getCountry()))) {
/*
* Language match.
* By making sure the available locale does not have a
* country and matches the preferred locale's language, we
* rule out "matches" based on the container's default
* locale. For example, if the preferred locale is
* "en-US", the container's default locale is "en-UK", and
* there is a resource bundle (with the requested base
* name) available for "en-UK", ResourceBundle.getBundle()
* will return it, but even though its language matches
* that of the preferred locale, we must ignore it,
* because matches based on the container's default locale
* are not portable across different containers with
* different default locales.
*/
match = bundle;
}
}
} catch (MissingResourceException mre) {
}
return match;
}
}