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

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

All Implemented Interfaces:

Loader<java.lang.String,V>

public abstract class ExtendletLoader<V>
extends java.lang.Object
implements Loader<java.lang.String,V>

A skeletal implementation of the loader used to implement an extendlet. All you have to do is to implement parse(java.io.InputStream, java.lang.String, java.lang.String) and getExtendletContext().

If the real path is not the same as the path specified in URL, you can override getRealPath(java.lang.String).

Since:

3.0.6

Author:

tomyeh

See Also:

Extendlet

Nested Class Summary

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

Loader.Resource<V>

Constructor Summary

protected

ExtendletLoader()

Method Summary

int	getCheckPeriod() Returns the check period, or -1 if the content is never changed.
protected abstract ExtendletContext	getExtendletContext() Returns the extendlet context.
long	getLastModified(java.lang.String src) Returns the last modified time.
protected java.lang.String	getRealPath(java.lang.String path) Returns the real path for the specified path.
V	load(java.lang.String src) Loads the resource.
protected abstract V	parse(java.io.InputStream is, java.lang.String path, java.lang.String orgpath) It is called to parse the resource into an intermediate format depending on Extendlet.
boolean	shallCheck(java.lang.String 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

ExtendletLoader

protected ExtendletLoader()

Method Detail

getRealPath

protected java.lang.String getRealPath(java.lang.String path)

Returns the real path for the specified path.

Default: return path, i.e., the path specified in URL is the real path.

Notice that parse(java.io.InputStream, java.lang.String, java.lang.String) will receive the original path (rather than the returned path).

Parameters:

path - the path specified in URL. Notice that it does NOT start with "~./". Rather it starts with "/". For example, "/zul/css/zk.wcs".

Since:

5.0.0

shallCheck

public boolean shallCheck(java.lang.String 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<java.lang.String,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(java.lang.String src)

Returns the last modified time.

Specified by:

getLastModified in interface Loader<java.lang.String,V>

load

public V load(java.lang.String 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<java.lang.String,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)

parse

protected abstract V parse(java.io.InputStream is,
                           java.lang.String path,
                           java.lang.String orgpath)
                    throws java.lang.Exception

It is called to parse the resource into an intermediate format depending on Extendlet.

The object is returned directly by load(java.lang.String), so you can return an instance of org.zkoss.util.resource.Loader.Resource to have more control on ResourceCache.

Parameters:

is - the content of the resource

path - the path of the resource. It is the value returned by getRealPath(java.lang.String), so called the real path

orgpath - the original path. It is the path passed to the path argument of getRealPath(java.lang.String). It is useful if you want to retrieve the additional information encoded into the URI.

Throws:

java.lang.Exception

Since:

5.0.0

getExtendletContext

protected abstract ExtendletContext getExtendletContext()

Returns the extendlet context.

getCheckPeriod

public int getCheckPeriod()

Returns the check period, or -1 if the content is never changed. Unit: milliseconds.

Default: It checks if an integer (unit: second) is assigned to a system property called org.zkoss.util.resource.extendlet.checkPeriod. If no such system property, -1 is assumed (never change). For the runtime environment the content is never changed, since all extendlet resources are packed in JAR files.