001 package com.croftsoft.core.lang.classloader;
002
003 import java.awt.*;
004 import java.io.*;
005 import java.lang.reflect.*;
006 import java.net.*;
007 import java.util.*;
008
009 /*********************************************************************
010 * <P>
011 * Upgrade this source code when the switch is made from Java 1.1 to
012 * Java 1.2.
013 * <P>
014 * <B>
015 * References
016 * </B>
017 * Scott Oaks, <U>Java Security</U>, O'Reilly, 1998.
018 * <P>
019 * @version
020 * 1998-09-06
021 * @author
022 * <a href="https://www.croftsoft.com/">David Wallace Croft</a>
023 *********************************************************************/
024
025 public class NetClassLoader extends CustomClassLoader
026 //////////////////////////////////////////////////////////////////////
027 //////////////////////////////////////////////////////////////////////
028 {
029
030 protected URL codebaseURL;
031
032 //////////////////////////////////////////////////////////////////////
033 //////////////////////////////////////////////////////////////////////
034
035 /*********************************************************************
036 * Loads a remote class and launches its main() method.
037 *
038 * @param
039 * Command-line arguments:
040 * <OL>
041 * <LI> The URL for the codebase.
042 * <LI> The name of the class with the "main(args)" method.
043 * <LI> Subsequent arguments to be passed to the invoked main method.
044 * </OL>
045 * Example
046 *********************************************************************/
047 public static void main ( String [ ] args )
048 throws Exception
049 //////////////////////////////////////////////////////////////////////
050 {
051 String [ ] shiftedArgs = new String [ args.length - 2 ];
052 for ( int i = 2; i < args.length; i++ )
053 {
054 shiftedArgs [ i - 2 ] = args [ i ];
055 }
056
057 launchMain ( args [ 0 ], args [ 1 ], shiftedArgs );
058 }
059
060 /*********************************************************************
061 * Loads a remote class and launches its main() method.
062 *********************************************************************/
063 public static void launchMain (
064 String codebaseURLName,
065 String mainClassName,
066 String [ ] args )
067 throws ClassNotFoundException,
068 IllegalAccessException,
069 MalformedURLException
070 //////////////////////////////////////////////////////////////////////
071 {
072 URL codebaseURL = new URL ( codebaseURLName );
073 ClassLoader classLoader = new NetClassLoader ( codebaseURL );
074 Class c = classLoader.loadClass ( mainClassName );
075 invokeMain ( c, args );
076 }
077
078 public static void invokeMain ( Class c, String [ ] args )
079 throws IllegalAccessException
080 //////////////////////////////////////////////////////////////////////
081 {
082 Method method;
083
084 try
085 {
086 method = c.getMethod ( "main",
087 new Class [ ] { String [ ].class } );
088 }
089 catch ( NoSuchMethodException ex )
090 {
091 System.err.println ( "No main() method in class \""
092 + c.getName ( ) + "\"." );
093 return;
094 }
095
096 try
097 {
098 method.invoke ( null, new Object [ ] { args } );
099 }
100 catch ( InvocationTargetException ex )
101 {
102 Throwable t = ex.getTargetException ( );
103 System.err.println (
104 "\"main()\" method exited with exception \"" + t + "\"." );
105 t.printStackTrace ( );
106 }
107 }
108
109 /*********************************************************************
110 * Ex: "http://www.mysticmayhem.com/lib/"
111 *********************************************************************/
112 public NetClassLoader ( URL codebaseURL )
113 //////////////////////////////////////////////////////////////////////
114 {
115 this.codebaseURL = codebaseURL;
116 }
117
118 protected byte [ ] loadClassData ( String name )
119 //////////////////////////////////////////////////////////////////////
120 {
121 try
122 {
123 String pathName = name.replace ( '.', '/' ) + ".class";
124 BufferedInputStream in = new BufferedInputStream (
125 getResourceAsStream ( pathName ) );
126 if ( in == null ) return null;
127 ByteArrayOutputStream out = new ByteArrayOutputStream ( );
128 int i;
129 while ( ( i = in.read ( ) ) > -1 ) out.write ( i );
130 in.close ( );
131 return out.toByteArray ( );
132 }
133 catch ( Exception ex ) { ex.printStackTrace ( ); return null; }
134 }
135
136 /*********************************************************************
137 *********************************************************************/
138 public URL getResource ( String name )
139 //////////////////////////////////////////////////////////////////////
140 {
141 try
142 {
143 return new URL ( codebaseURL, name );
144 }
145 catch ( Exception ex ) { ex.printStackTrace ( ); return null; }
146 }
147
148 /*********************************************************************
149 * Loads a stream from the URL given by getResource(name).
150 * Does not use a cache.
151 *********************************************************************/
152 public InputStream getResourceAsStream ( String name )
153 //////////////////////////////////////////////////////////////////////
154 {
155 try
156 {
157 URL url = getResource ( name );
158 System.out.println ( "Loading \"" + url + "\"..." );
159 URLConnection urlConnection = url.openConnection ( );
160 if ( urlConnection instanceof HttpURLConnection )
161 {
162 HttpURLConnection httpURLConnection
163 = ( HttpURLConnection ) urlConnection;
164 httpURLConnection.setFollowRedirects ( true );
165 httpURLConnection.setRequestMethod ( "GET" );
166 int responseCode = httpURLConnection.getResponseCode ( );
167 System.out.println (
168 httpURLConnection.getResponseMessage ( )
169 + ", " + httpURLConnection.getContentLength ( ) + " bytes"
170 + ", " + new Date ( httpURLConnection.getDate ( ) )
171 + ", " + new Date ( httpURLConnection.getLastModified ( ) ) );
172 if ( responseCode != HttpURLConnection.HTTP_OK )
173 {
174 return null;
175 }
176 }
177 return urlConnection.getInputStream ( );
178 }
179 catch ( Exception ex ) { ex.printStackTrace ( ); return null; }
180 }
181
182 /*********************************************************************
183 * Creates the image by calling getResourceAsStream(imageName).
184 *********************************************************************/
185 public Image createImage ( String imageName )
186 throws IOException
187 //////////////////////////////////////////////////////////////////////
188 {
189 InputStream inputStream = getResourceAsStream ( imageName );
190 BufferedInputStream in = new BufferedInputStream ( inputStream );
191 ByteArrayOutputStream out = new ByteArrayOutputStream ( );
192 int i;
193 while ( ( i = in.read ( ) ) > -1 ) out.write ( i );
194 byte [ ] imageData = out.toByteArray ( );
195 out.close ( );
196 in.close ( );
197 return Toolkit.getDefaultToolkit ( ).createImage ( imageData );
198 }
199
200 //////////////////////////////////////////////////////////////////////
201 //////////////////////////////////////////////////////////////////////
202 }