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package com.sun.appserv.web.taglibs.cache;
import java.util.ResourceBundle;
import java.util.logging.Logger;
import java.util.logging.Level;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import com.sun.enterprise.web.logging.pwc.LogDomains;
import com.sun.appserv.util.cache.Cache;
/**
* FlushTag is a JSP tag that is used with the CacheTag. The FlushTag
* allows you to invalidate a complete cache or a particular cache element
* identified by the key.
*
* Usage Example:
* <%@ taglib prefix="ias" uri="Sun ONE Application Server Tags" %>
* <ias:flush key="<%= cacheKey %>" />
*/
public class FlushTag extends TagSupport
{
/**
* The key for the cache entry that needs to be flushed.
*/
private String _key;
/**
* This specifies the scope of the cache that needs to be flushed.
*/
private int _scope = PageContext.APPLICATION_SCOPE;
/**
* The logger to use for logging ALL web container related messages.
*/
private static Logger _logger = null;
/**
* This indicates whether debug logging is on or not
*/
private static boolean _debugLog;
/**
* The resource bundle containing the localized message strings.
*/
private static ResourceBundle _rb = null;
// ---------------------------------------------------------------------
// Constructor and initialization
/**
* Default constructor that simply gets a handle to the web container
* subsystem's logger.
*/
public FlushTag() {
super();
if (_logger == null) {
_logger = LogDomains.getLogger(LogDomains.PWC_LOGGER);
_rb = _logger.getResourceBundle();
_debugLog = _logger.isLoggable(Level.FINE);
}
}
// ---------------------------------------------------------------------
// Tag logic
/**
* doStartTag is called when the flush tag is encountered. By
* the time this is called, the tag attributes are already set.
*
* @throws JspException the standard exception thrown
* @return SKIP_BODY since the tag should be empty
*/
public int doStartTag()
throws JspException
{
// get the cache from the specified scope
Cache cache = CacheUtil.getCache(pageContext, _scope);
// generate the cache key using the user specified key.
if (_key != null) {
String key = CacheUtil.generateKey(_key, pageContext);
// remove the entry for the key
cache.remove(key);
if (_debugLog)
_logger.fine("FlushTag: clear ["+ key +"]");
} else {
// clear the entire cache
cache.clear();
if (_debugLog)
_logger.fine("FlushTag: clear cache");
}
return SKIP_BODY;
}
/**
* doEndTag just resets all the valiables in case the tag is reused
*
* @throws JspException the standard exception thrown
* @return always returns EVAL_PAGE since we want the entire jsp evaluated
*/
public int doEndTag()
throws JspException
{
_key = null;
_scope = PageContext.APPLICATION_SCOPE;
return EVAL_PAGE;
}
// ---------------------------------------------------------------------
// Attribute setters
/**
* This is set a key for the cache element that needs to be cleared
*/
public void setKey(String key) {
if (key != null && key.length() > 0)
_key = key;
}
/**
* Sets the scope of the cache.
*
* @param scope the scope of the cache
*
* @throws IllegalArgumentException if the specified scope is different
* from request, session, and application
*/
public void setScope(String scope) {
_scope = CacheUtil.convertScope(scope);
}
}