org.apache.commons.digester3.plugins.PluginContext Maven / Gradle / Ivy
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package org.apache.commons.digester3.plugins;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import java.util.List;
import java.util.LinkedList;
import org.apache.commons.digester3.plugins.strategies.FinderFromClass;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltClass;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltMethod;
import org.apache.commons.digester3.plugins.strategies.FinderFromDfltResource;
import org.apache.commons.digester3.plugins.strategies.FinderFromFile;
import org.apache.commons.digester3.plugins.strategies.FinderFromMethod;
import org.apache.commons.digester3.plugins.strategies.FinderFromResource;
import org.apache.commons.digester3.plugins.strategies.FinderSetProperties;
/**
* Provides data and services which should exist only once per digester.
*
* This class holds a number of useful items which should be shared by all plugin objects. Such data cannot be stored on
* the PluginRules or PluginManager classes, as there can be multiple instances of these at various times during a
* parse.
*
* The name "Context" refers to the similarity between this class and a ServletContext class in a servlet engine. A
* ServletContext object provides access to the container's services such as obtaining global configuration parameters
* for the container, or getting access to logging services. For plugins, a Digester instance can be regarded as
* "the container".
*
* @since 1.6
*/
public class PluginContext
{
private static final String DFLT_PLUGIN_CLASS_ATTR_NS = null;
private static final String DFLT_PLUGIN_CLASS_ATTR = "plugin-class";
// the xml attribute the user uses on an xml element to specify
// the plugin's class
private static final String DFLT_PLUGIN_ID_ATTR_NS = null;
private static final String DFLT_PLUGIN_ID_ATTR = "plugin-id";
/** See {@link #setPluginClassAttribute}. */
private String pluginClassAttrNs = DFLT_PLUGIN_CLASS_ATTR_NS;
/** See {@link #setPluginClassAttribute}. */
private String pluginClassAttr = DFLT_PLUGIN_CLASS_ATTR;
/** See {@link #setPluginClassAttribute}. */
private String pluginIdAttrNs = DFLT_PLUGIN_ID_ATTR_NS;
/** See {@link #setPluginClassAttribute}. */
private String pluginIdAttr = DFLT_PLUGIN_ID_ATTR;
/**
* A list of RuleFinder objects used by all Declarations (and thus indirectly by all PluginCreateRules to locate the
* custom rules for plugin classes.
*/
private List ruleFinders;
// ------------------- methods ---------------------------------------
/**
* Return the list of RuleFinder objects. Under normal circumstances this method creates a default list of these
* objects when first called (ie "on-demand" or "lazy initialization"). However if setRuleFinders has been called
* first, then the list specified there is returned.
*
* It is explicitly permitted for the caller to modify this list by inserting or removing RuleFinder objects.
*
* @return the list of RuleFinder objects
*/
public List getRuleFinders()
{
if ( ruleFinders == null )
{
// when processing a plugin declaration, attempts are made to
// find custom rules in the order in which the Finder objects
// are added below. However this list can be modified
ruleFinders = new LinkedList();
ruleFinders.add( new FinderFromFile() );
ruleFinders.add( new FinderFromResource() );
ruleFinders.add( new FinderFromClass() );
ruleFinders.add( new FinderFromMethod() );
ruleFinders.add( new FinderFromDfltMethod() );
ruleFinders.add( new FinderFromDfltClass() );
ruleFinders.add( new FinderFromDfltResource() );
ruleFinders.add( new FinderFromDfltResource( ".xml" ) );
ruleFinders.add( new FinderSetProperties() );
}
return ruleFinders;
}
/**
* Set the list of RuleFinder objects. This may be useful if working in a non-english language, allowing the
* application developer to replace the standard list with a list of objects which look for xml attributes in the
* local language.
*
* If the intent is just to add an additional rule-finding algorithm, then it may be better to call #getRuleFinders,
* and insert a new object into the start of the list.
*
* @param ruleFinders the list of RuleFinder objects
*/
public void setRuleFinders( List ruleFinders )
{
this.ruleFinders = ruleFinders;
}
/**
* Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which class should be
* instantiated.
*
* Example:
*
*
* setPluginClassAttribute( null, "class" );
*
*
* will allow this in the input xml:
*
*
* <root>
* <some-plugin class="com.acme.widget"> ......
*
*
* instead of the default syntax:
*
*
* <root>
* <some-plugin plugin-class="com.acme.widget"> ......
*
*
* This is particularly useful if the input xml document is not in English.
*
* Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
*
* @param namespaceUri is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
* then this should be null. Note that if a namespace is used, the attrName value should not
* contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
* this parameter must be null.
* @param attrName is the attribute whose value contains the name of the class to be instantiated.
*/
public void setPluginClassAttribute( String namespaceUri, String attrName )
{
pluginClassAttrNs = namespaceUri;
pluginClassAttr = attrName;
}
/**
* Sets the xml attribute which the input xml uses to indicate to a PluginCreateRule which plugin declaration is
* being referenced.
*
* Example:
*
*
* setPluginIdAttribute( null, "id" );
*
*
* will allow this in the input xml:
*
*
* <root>
* <some-plugin id="widget"> ......
*
*
* rather than the default behaviour:
*
*
* <root>
* <some-plugin plugin-id="widget"> ......
*
*
* This is particularly useful if the input xml document is not in English.
*
* Note that the xml attributes used by PluginDeclarationRules are not affected by this method.
*
* @param namespaceUri is the namespace uri that the specified attribute is in. If the attribute is in no namespace,
* then this should be null. Note that if a namespace is used, the attrName value should not
* contain any kind of namespace-prefix. Note also that if you are using a non-namespace-aware parser,
* this parameter must be null.
* @param attrName is the attribute whose value contains the id of the plugin declaration to be used when
* instantiating an object.
*/
public void setPluginIdAttribute( String namespaceUri, String attrName )
{
pluginIdAttrNs = namespaceUri;
pluginIdAttr = attrName;
}
/**
* Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.
*
* May be null (in fact, normally will be).
*
* @return the namespace for the xml attribute which indicates which class is to be plugged in.
*/
public String getPluginClassAttrNs()
{
return pluginClassAttrNs;
}
/**
* Get the namespace for the xml attribute which indicates to a PluginCreateRule which class is to be plugged in.
*
* The return value is never null.
*
* @return the namespace for the xml attribute which indicates which class is to be plugged in.
*/
public String getPluginClassAttr()
{
return pluginClassAttr;
}
/**
* Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
* should be used.
*
* May be null (in fact, normally will be).
*
* @return the namespace for the xml attribute which indicates which previous plugin declaration should be used.
*/
public String getPluginIdAttrNs()
{
return pluginIdAttrNs;
}
/**
* Get the namespace for the xml attribute which indicates to a PluginCreateRule which previous plugin declaration
* should be used.
*
* The return value is never null.
*
* @return the namespace for the xml attribute which indicates which previous plugin declaration should be used.
*/
public String getPluginIdAttr()
{
return pluginIdAttr;
}
}