Sun Java System Web Server 7.0 Update 5 Developer's Guide to Java Web Applications

CacheKeyGenerator Interface

The built-in default CacheHelper implementation enables web applications to customize the key generation. An application component in a servlet or JSP can set up a custom CacheKeyGenerator implementation as an attribute in the ServletContext.

The name of the context attribute is configurable as the value of the cacheKeyGeneratorAttrName property in the default-helper element of the sun-web.xml deployment descriptor. For more information, see default-helper.

The CacheKeyGenerator interface contains the following information:

package com.sun.appserv.web.cache;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
/** CacheKeyGenerator: a helper interface to generate the key that
 * is used to cache this request.
 * Name of the ServletContext attribute implementing the
 * CacheKeyGenerator is configurable via a property of the
 * default-helper in sun-web.xml:
 * <default-helper>
 * <property
 * name="cacheKeyGeneratorAttrName"
 * value="com.acme.web.MyCacheKeyGenerator" />
 * </default-helper>
 * Caching engine looks up the specified attribute in the servlet
 * context; the result of the lookup must be an implementation of the
 * CacheKeyGenerator interface.
public interface CacheKeyGenerator {
/** getCacheKey: generate the key to be used to cache the
    * response.
    * @param context the web application context
    * @param request incoming <code>HttpServletRequest</code>
    * @returns key string used to access the cache entry.
    * if the return value is null, a default key is used.
   public String getCacheKey(ServletContext context,
                           HttpServletRequest request);