CBResourceLoader


1   package com.ca.commons.cbutil;
2   
3   import java.awt.*;
4   import java.io.InputStream  ;
5   import java.util.*;
6   import java.util.logging.Logger  ;
7   import java.util.zip.ZipException  ;
8   
9   /**
10   * This Class provides access to a group of zip files.  In the case of namespace conflicts between
11   * Zip files, the first zip file registered has priority.  The zip files are accessed through CBJarResource.
12   *
13   * @author Chris Betts
14   * @see com.ca.commons.cbutil.CBJarResource
15   */
16  
17  
18  public class CBResourceLoader
19  {
20      /**
21       * a cached list of 'unknown' resources that have been (unsuccessfully) looked up before.
22       */
23  
24      protected HashSet unknownResources = new HashSet();
25  
26      /**
27       * A list of CBJarResources objects that may be searched for packaged resources.
28       */
29  
30      protected CBJarResource[] resourceFiles = null;
31  
32      /**
33       * Whether to print out shtuff on the way.
34       */
35  
36      protected static boolean debug = false;
37  
38  
39      private static Logger   log = Logger.getLogger(CBResourceLoader.class.getName());
40  
41      /**
42       * Constructor - note that that the class is useless until at least one resource file has been
43       * registered with it using the addResource() method.
44       */
45  
46      public CBResourceLoader()
47      {
48          log.fine("Started CBResourceLoader");
49      }
50  
51      /**
52       * Adds a new zip/jar resource file to the list of files to be examined for resources.
53       */
54  
55      public void addResource(CBJarResource resource)
56      {
57          int size = (resourceFiles == null) ? 0 : (resourceFiles.length);
58  
59          // The clumsiness of using an array is balanced by the need for quick
60          // access, and the fact that normally only a small number of resources are added,
61          // and only at the start of program operation.
62  
63          CBJarResource[] newArray = new CBJarResource[size + 1];
64          for (int i = 0; i < size; i++)
65              newArray[i] = resourceFiles[i];
66          newArray[size] = resource;
67          resourceFiles = newArray;
68  
69          log.fine("Added CBJarResource: " + resource.toString());
70      }
71  
72      /**
73       * Search all registered zip files for a particular file, and return an input stream to that
74       * file.
75       */
76  
77      public InputStream   getInputStream(String   resourceName) throws ZipException  
78      {
79          CBJarResource resourceFile = getJarContainingResource(resourceName);
80          if (resourceFile != null)
81              return resourceFile.getInputStream(resourceName);
82  
83          throw new ZipException  ("File: '" + resourceName + "' not found");
84      }
85  
86      /**
87       * Search all registered zip files for a particular Image, and return an awt Image
88       * object.
89       */
90  
91      public Image getImage(String   imageName, Toolkit imageCreator) throws ZipException  
92      {
93          CBJarResource resourceFile = getJarContainingResource(imageName);
94          if (resourceFile != null)
95              return resourceFile.getImage(imageName, imageCreator);
96  
97          throw new ZipException  ("Image File: '" + imageName + "' not found");
98      }
99  
100     /**
101      * Search all registered zip files for a particular file, and return the data within that
102      * file as a byte array.  (This might be used to initialise a String object if the file is
103      * a text file, for instance.)
104      */
105 
106     public byte[] getResource(String   resourceName) throws ZipException  
107     {
108         log.finer("  $$ getting resource '" + resourceName + "' from CBResourceLoader");
109         CBJarResource resourceFile = getJarContainingResource(resourceName);
110         if (resourceFile != null)
111         {
112             log.finer("  $$ found resource '" + resourceName + "' in zip file '" + resourceFile.getZipFileName() + "' - extracting");
113             return resourceFile.getResource(resourceName);
114         }
115         throw new ZipException  ("File: '" + resourceName + "' not found");
116 
117     }
118 
119     public long getLastModified(String   resourceName) throws ZipException  
120     {
121         CBJarResource resourceFile = getJarContainingResource(resourceName);
122         if (resourceFile != null)
123         {
124             return resourceFile.getLastModified();
125         }
126         throw new ZipException  ("File: '" + resourceName + "' not found");
127 
128     }
129 
130 
131     /**
132      * Searches an internal hash, followed by all Jar files, for a particular resource.
133      */
134     public CBJarResource getJarContainingResource(String   resourceName)
135     {
136         if (resourceFiles == null) return null;  // we don't have any resources...
137     
138         // check to see if we've already looked for this resource.
139         if (unknownResources.contains(resourceName)) return null;
140 
141         for (int i = 0; i < resourceFiles.length; i++)
142             if (resourceFiles[i].hasResource(resourceName))
143                 return resourceFiles[i];
144 
145         // nothing found!  Add an entry to the unknownResources hashset so that we don't look for
146         // it again.
147 
148         unknownResources.add(resourceName);
149 
150         return null; // nothing found
151     }
152 
153     /**
154      * Returns all resources with the given prefix.
155      *
156      * @param prefix a string to match the start of resources against, e.g. 'icons/'
157      */
158 
159     public String  [] getPrefixedResources(String   prefix)
160     {
161         if (resourceFiles == null) return new String  []{};  // don't have anything.
162 
163         Vector resources = new Vector();
164 
165         // cycle through all resource files, gathering prefixed resources.
166         // name clashes are simply included twice :-)
167                 
168         for (int i = 0; i < resourceFiles.length; i++)
169         {
170             resources.addAll(Arrays.asList(resourceFiles[i].getPrefixedResources(prefix)));
171         } 
172         
173         // cast stuff back to string for return.
174         if (resources.size() == 0)
175         {
176             return new String  []{};
177         }
178         else
179         {
180             return (String  []) resources.toArray(new String  [resources.size()]);
181         }
182     }
183 
184     /**
185      * This is a very PRIMATIVE wildcard matching routine - it allows
186      * only ONE wildcard, and that wildcard MUST be a '*' character.
187      * (So in effect this is simply a prefix + suffix match).
188      *
189      * @param exp a SIMPLE wildcard expression to match, e.g. 'templates/plain*.html'
190      */
191 
192 /*
193 XXX Under Development...
194 
195     public String[] getWildCardResources(String exp)
196     {
197         if (resourceFiles == null) return new String[]{};  // don't have anything.to search
198 
199         int wildpos = exp.indexOf('*');
200         if (wildpos == -1) return new String[]{exp};
201 
202         if (wildpos == exp.length() - 1) // i.e. last character
203             return getPrefixedResources(exp.substring(0, exp.length() - 1));
204 
205         Vector resources = new Vector();
206 
207         // cycle through all resource files, gathering prefixed resources.
208         // name clashes are simply included twice :-)
209 
210         String prefix = exp.substring(0, wildpos);
211         String suffix = exp.substring(wildpos + 1);
212 
213         for (int i = 0; i < resourceFiles.length; i++)
214         {
215             resources.addAll(Arrays.asList(resourceFiles[i].getBoundedResources(prefix, suffix)));
216         }
217 
218         // cast stuff back to string for return.
219         if (resources.size() == 0)
220         {
221             return new String[]{};
222         }
223         else
224         {
225             return (String[]) resources.toArray(new String[resources.size()]);
226         }
227     }
228 */
229 }
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