org.zkoss.web.util.resource
Class ResourceLoader<V>

java.lang.Object
  org.zkoss.web.util.resource.ResourceLoader<V>

All Implemented Interfaces:

Loader<org.zkoss.web.util.resource.ResourceInfo,V>

public abstract class ResourceLoader<V>
extends java.lang.Object
implements Loader<org.zkoss.web.util.resource.ResourceInfo,V>

A semi-implemented loader to used with ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object) to retrieve servlet resources.

Author:

tomyeh

Nested Class Summary

Nested classes/interfaces inherited from interface org.zkoss.util.resource.Loader

Loader.Resource<V>

Constructor Summary

protected

ResourceLoader()

Method Summary

long	getLastModified(org.zkoss.web.util.resource.ResourceInfo src) Returns the last modified time, or -1 if reload is required or not exists.
V	load(org.zkoss.web.util.resource.ResourceInfo src) Loads the resource.
protected abstract V	parse(java.lang.String path, java.io.File file, java.lang.Object extra) Parses the specified file and returns the result which will be stored into the cache (ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object)).
protected abstract V	parse(java.lang.String path, java.net.URL url, java.lang.Object extra) Parses the specified URL and returns the result which will be stored into the cache (ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object)).
boolean	shallCheck(org.zkoss.web.util.resource.ResourceInfo src, long expiredMillis) Returns whether to call Loader.getLastModified(K).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ResourceLoader

protected ResourceLoader()

Method Detail

parse

protected abstract V parse(java.lang.String path,
                           java.io.File file,
                           java.lang.Object extra)
                    throws java.lang.Exception

Parses the specified file and returns the result which will be stored into the cache (ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object)).

Deriving must override this method.

Parameters:

extra - the extra parameter passed from ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object).

Throws:

java.lang.Exception

parse

protected abstract V parse(java.lang.String path,
                           java.net.URL url,
                           java.lang.Object extra)
                    throws java.lang.Exception

Parses the specified URL and returns the result which will be stored into the cache (ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object)).

Deriving must override this method.

Parameters:

extra - the extra parameter passed from ResourceCaches.get(org.zkoss.web.util.resource.ResourceCache, javax.servlet.ServletContext, java.lang.String, java.lang.Object).

Throws:

java.lang.Exception

shallCheck

public boolean shallCheck(org.zkoss.web.util.resource.ResourceInfo src,
                          long expiredMillis)

Description copied from interface: Loader

Returns whether to call Loader.getLastModified(K). If false, it assumes the current cached content is up-to-date.

Specified by:

shallCheck in interface Loader<org.zkoss.web.util.resource.ResourceInfo,V>

expiredMillis - how many milli-seconds are expired after the last check. In most cases, just return true if expiredMillis > 0

getLastModified

public long getLastModified(org.zkoss.web.util.resource.ResourceInfo src)

Description copied from interface: Loader

Returns the last modified time, or -1 if reload is required or not exists.

Specified by:

getLastModified in interface Loader<org.zkoss.web.util.resource.ResourceInfo,V>

load

public V load(org.zkoss.web.util.resource.ResourceInfo src)
       throws java.lang.Exception

Description copied from interface: Loader

Loads the resource.

The returned resource could be anything. It will be returned by ResourceCache.get(java.lang.Object). However, if you want to have more control (e.g., whether to cache), you can return an instance of Loader.Resource. Then, the return value of ResourceCache.get(java.lang.Object) will be Loader.Resource.resource.

Specified by:

load in interface Loader<org.zkoss.web.util.resource.ResourceInfo,V>

Returns:

null if not found

Throws:

java.lang.Exception - you might throw any exception which will be passed back to the caller of ResourceCache.get(java.lang.Object)