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package org.jvnet.lafplugin;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import javax.swing.UIDefaults;
/**
* Plugin manager for look-and-feels.
*
* @author Kirill Grouchnikov
* @author Erik Vickroy
* @author Robert Beeger
* @author Frederic Lavigne
* @author Pattrick Gotthardt
*/
public class PluginManager {
private String mainTag;
private String pluginTag;
private String xmlName;
private Set plugins;
/**
* Simple constructor.
*
* @param xmlName
* The name of XML file that contains plugin configuration.
* @param mainTag
* The main tag in the XML configuration file.
* @param pluginTag
* The tag that corresponds to a single plugin kind. Specifies
* the plugin kind that will be located in
* {@link #getAvailablePlugins(boolean)}.
*/
public PluginManager(String xmlName, String mainTag, String pluginTag) {
this.xmlName = xmlName;
this.mainTag = mainTag;
this.pluginTag = pluginTag;
this.plugins = null;
}
// protected String getPluginClass(URL pluginUrl) {
// InputStream is = null;
// try {
// DocumentBuilder builder = DocumentBuilderFactory.newInstance()
// .newDocumentBuilder();
// is = pluginUrl.openStream();
// Document doc = builder.parse(is);
// Node root = doc.getFirstChild();
// if (!this.mainTag.equals(root.getNodeName()))
// return null;
// NodeList children = root.getChildNodes();
// for (int i = 0; i < children.getLength(); i++) {
// Node child = children.item(i);
// if (!this.pluginTag.equals(child.getNodeName()))
// continue;
// if (child.getChildNodes().getLength() != 1)
// return null;
// Node text = child.getFirstChild();
// if (text.getNodeType() != Node.TEXT_NODE)
// return null;
// return text.getNodeValue();
// }
// return null;
// } catch (Exception exc) {
// return null;
// } finally {
// if (is != null) {
// try {
// is.close();
// } catch (Exception e) {
// }
// }
// }
// }
//
protected String getPluginClass(URL pluginUrl) {
InputStream is = null;
InputStreamReader isr = null;
try {
XMLElement xml = new XMLElement();
is = pluginUrl.openStream();
isr = new InputStreamReader(is);
xml.parseFromReader(isr);
if (!this.mainTag.equals(xml.getName()))
return null;
Enumeration children = xml.enumerateChildren();
while (children.hasMoreElements()) {
XMLElement child = (XMLElement) children.nextElement();
if (!this.pluginTag.equals(child.getName()))
continue;
if (child.countChildren() != 0)
return null;
return child.getContent();
}
return null;
} catch (Exception exc) {
return null;
} finally {
if (isr != null) {
try {
isr.close();
} catch (Exception e) {
}
}
if (is != null) {
try {
is.close();
} catch (Exception e) {
}
}
}
}
protected Object getPlugin(URL pluginUrl) throws Exception {
String pluginClassName = this.getPluginClass(pluginUrl);
if (pluginClassName == null)
return null;
Class pluginClass = Class.forName(pluginClassName);
if (pluginClass == null)
return null;
Object pluginInstance = pluginClass.newInstance();
if (pluginInstance == null)
return null;
return pluginInstance;
}
/**
* Returns a collection of all available plugins.
*
* @return Collection of all available plugins. The classpath is scanned
* only once.
* @see #getAvailablePlugins(boolean)
*/
public Set getAvailablePlugins() {
return this.getAvailablePlugins(false);
}
/**
* Returns a collection of all available plugins. The parameter specifies
* whether the classpath should be rescanned or whether to return the
* already found plugins (after first-time scan).
*
* @param toReload
* If <code>true</code>, the classpath is scanned for
* available plugins every time <code>this</code> function is
* called. If <code>false</code>, the classpath scan is
* performed only once. The consecutive calls return the cached
* result.
* @return Collection of all available plugins.
*/
public Set getAvailablePlugins(boolean toReload) {
if (toReload && (this.plugins != null))
return this.plugins;
this.plugins = new HashSet();
ClassLoader cl = PluginManager.class.getClassLoader();
try {
Enumeration urls = cl.getResources(this.xmlName);
while (urls.hasMoreElements()) {
URL pluginUrl = (URL) urls.nextElement();
Object pluginInstance = this.getPlugin(pluginUrl);
if (pluginInstance != null)
this.plugins.add(pluginInstance);
}
} catch (Exception exc) {
return null;
}
return plugins;
}
}
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