001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU
007: * General Public License Version 2 only ("GPL") or the Common
008: * Development and Distribution License("CDDL") (collectively, the
009: * "License"). You may not use this file except in compliance with the
010: * License. You can obtain a copy of the License at
011: * http://www.netbeans.org/cddl-gplv2.html
012: * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
013: * specific language governing permissions and limitations under the
014: * License. When distributing the software, include this License Header
015: * Notice in each file and include the License file at
016: * nbbuild/licenses/CDDL-GPL-2-CP. Sun designates this
017: * particular file as subject to the "Classpath" exception as provided
018: * by Sun in the GPL Version 2 section of the License file that
019: * accompanied this code. If applicable, add the following below the
020: * License Header, with the fields enclosed by brackets [] replaced by
021: * your own identifying information:
022: * "Portions Copyrighted [year] [name of copyright owner]"
023: *
024: * Contributor(s):
025: *
026: * The Original Software is NetBeans. The Initial Developer of the Original
027: * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
028: * Microsystems, Inc. All Rights Reserved.
029: *
030: * If you wish your version of this file to be governed by only the CDDL
031: * or only the GPL Version 2, indicate your decision by adding
032: * "[Contributor] elects to include this software in this distribution
033: * under the [CDDL or GPL Version 2] license." If you do not indicate a
034: * single choice of license, a recipient has the option to distribute
035: * your version of this file under either the CDDL, the GPL Version 2 or
036: * to extend the choice of license to its licensees as provided above.
037: * However, if you add GPL Version 2 code and therefore, elected the GPL
038: * Version 2 license, then the option applies only if the new code is
039: * made subject to such option by the copyright holder.
040: */
041:
042: package org.netbeans.modules.navigator;
043:
044: import java.util.Collection;
045: import java.util.HashMap;
046: import java.util.Map;
047: import org.netbeans.spi.navigator.NavigatorPanel;
048: import org.openide.util.Lookup;
049: import org.openide.util.lookup.Lookups;
050:
051: /**
052: * Storage/lookup of NavigatorPanel providers. Providers are mapped to
053: * mime types they support.
054: *
055: * @author Dafe Simonek
056: */
057: class ProviderRegistry {
058:
059: /** folder in layer file system where navigator panels are searched for */
060: private static final String PANELS_FOLDER = "/Navigator/Panels/"; //NOI18N
061: /** template for finding all NavigatorPanel instances in lookup */
062: private static final Lookup.Template<NavigatorPanel> NAV_PANEL_TEMPLATE = new Lookup.Template<NavigatorPanel>(
063: NavigatorPanel.class);
064:
065: /** singleton instance */
066: private static ProviderRegistry instance;
067:
068: /** Mapping between mime types and provider instances. Note that
069: * Collections.EMPTY_LIST serves as special value telling us that
070: * we already searched for providers for specific content type and found
071: * no providers. This ensures no useless repetitive searches.
072: */
073: private Map<String, Collection<? extends NavigatorPanel>> contentTypes2Providers;
074:
075: /** Singleton, no external instantiation */
076: private ProviderRegistry() {
077: }
078:
079: /********* public area *********/
080:
081: public static ProviderRegistry getInstance() {
082: if (instance == null) {
083: instance = new ProviderRegistry();
084: }
085: return instance;
086: }
087:
088: /** Finds appropriate providers for given data content type
089: * (similar to mime type)
090: * and returns list of provider classes.
091: *
092: * @return Collection of providers, which implements NavigatorPanel interface.
093: * Never return null, only empty List if no provider exists for given content type.
094: */
095: public Collection<? extends NavigatorPanel> getProviders(
096: String contentType) {
097: if (contentTypes2Providers == null) {
098: contentTypes2Providers = new HashMap<String, Collection<? extends NavigatorPanel>>(
099: 15);
100: }
101: Collection<? extends NavigatorPanel> result = contentTypes2Providers
102: .get(contentType);
103: if (result == null) {
104: // load and instantiate provider classes
105: result = loadProviders(contentType);
106: contentTypes2Providers.put(contentType, result);
107: }
108:
109: return result;
110: }
111:
112: /******* private stuff ***********/
113:
114: /** Returns collection of NavigatorPanels or empty collection if no provider
115: * exist for given content type
116: */
117: private Collection<? extends NavigatorPanel> loadProviders(
118: String contentType) {
119: String path = PANELS_FOLDER + contentType;
120:
121: Lookup.Result<NavigatorPanel> result = Lookups.forPath(path)
122: .lookup(NAV_PANEL_TEMPLATE);
123:
124: return result.allInstances();
125: }
126:
127: }
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