001 /*
002 * Copyright 2005 Stephen J. McConnell.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
013 * implied.
014 *
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package net.dpml.transit.local;
020
021 import java.io.IOException;
022 import java.io.InputStream;
023 import java.io.FileInputStream;
024 import java.io.OutputStream;
025 import java.io.FileOutputStream;
026 import java.io.File;
027 import java.net.URI;
028 import java.net.URL;
029 import java.net.URLConnection;
030 import java.security.AccessController;
031 import java.security.PrivilegedExceptionAction;
032 import java.security.PrivilegedActionException;
033 import java.security.PrivilegedAction;
034
035 import net.dpml.transit.Transit;
036 import net.dpml.transit.Artifact;
037
038 /**
039 * The local URL protocol connection implementation.
040 * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
041 * @version 1.1.0
042 */
043 public class LocalURLConnection extends URLConnection
044 {
045 private boolean m_connected;
046
047 private File m_target;
048
049 /**
050 * Creation of a new local handler.
051 * @param url the url to establish a connection with
052 * @exception NullPointerException if the url argument is null
053 */
054 LocalURLConnection( URL url )
055 throws NullPointerException
056 {
057 super( url );
058
059 m_connected = false;
060 }
061
062 /**
063 * Establish a connection.
064 *
065 * @exception IOException is an error occurs while attempting to establish
066 * the connection.
067 */
068 public void connect()
069 throws IOException
070 {
071 if( m_connected )
072 {
073 return;
074 }
075
076 m_connected = true;
077
078 try
079 {
080 AccessController.doPrivileged(
081 new PrivilegedExceptionAction()
082 {
083 public Object run()
084 throws IOException
085 {
086 String spec = url.toExternalForm();
087 try
088 {
089 Artifact artifact = Artifact.createArtifact( spec );
090 String groupSpec = artifact.getGroup();
091 String artifactName = artifact.getName();
092 String typeSpec = artifact.getType();
093 String versionSpec = artifact.getVersion();
094 File prefs = Transit.DPML_PREFS;
095 File group = new File( prefs, groupSpec );
096 File type = new File( group, typeSpec + "s" );
097 if( null == versionSpec )
098 {
099 final String filename = artifactName + "." + typeSpec;
100 m_target = new File( type, filename );
101 }
102 else
103 {
104 final String filename = artifactName + "-" + versionSpec + "." + typeSpec;
105 m_target = new File( type, filename );
106 }
107 }
108 catch( Throwable e )
109 {
110 String message = e.getMessage();
111 IOException exception = new IOException( message );
112 exception.initCause( e.getCause() );
113 throw exception;
114 }
115 return null; // nothing to return
116 }
117 }
118 );
119 }
120 catch( PrivilegedActionException e )
121 {
122 throw (IOException) e.getException();
123 }
124 }
125
126 /**
127 * Return an input stream to the resource.
128 * @return the input stream
129 * @exception IOException is an error occurs
130 */
131 public InputStream getInputStream()
132 throws IOException
133 {
134 connect();
135 if( m_target == null )
136 {
137 return null;
138 }
139 else
140 {
141 return new FileInputStream( m_target );
142 }
143 }
144
145 /**
146 * Return an output stream to the resource.
147 * @return the output stream
148 * @exception IOException if any I/O problems occur.
149 */
150 public OutputStream getOutputStream()
151 throws IOException
152 {
153 connect();
154 if( m_target == null )
155 {
156 return null;
157 }
158 else
159 {
160 if( !m_target.exists() )
161 {
162 File parent = m_target.getParentFile();
163 if( null != parent )
164 {
165 parent.mkdirs();
166 }
167 m_target.createNewFile();
168 }
169 return new FileOutputStream( m_target );
170 }
171 }
172
173 /**
174 * Return the content for this local resource.
175 * @param classes a sequence of classes against which the
176 * implementation will attempt to establish a known match
177 * @return the content object (possibly null)
178 * @exception IOException is an error occurs
179 */
180 public Object getContent( final Class[] classes )
181 throws IOException
182 {
183 connect();
184 Object result = AccessController.doPrivileged(
185 new PrivilegedAction()
186 {
187 public Object run()
188 {
189 for( int i=0; i < classes.length; i++ )
190 {
191 Class c = classes[i];
192 if( c.equals( File.class ) )
193 {
194 return m_target;
195 }
196 }
197 return null;
198 }
199 }
200 );
201
202 if( null != result )
203 {
204 return result;
205 }
206 else
207 {
208 if( null != m_target )
209 {
210 URI uri = m_target.toURI();
211 URL url = uri.toURL();
212 return url.getContent( classes );
213 }
214 else
215 {
216 return super.getContent( classes );
217 }
218 }
219 }
220 }