ProjectFile


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2    * 
3    * The ObjectStyle Group Software License, version 1.1
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6    * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
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21   * 3. The end-user documentation included with the redistribution, if any,
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24   *    and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
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56  package org.objectstyle.cayenne.project;
57  
58  import java.io.File  ;
59  import java.io.FileOutputStream  ;
60  import java.io.IOException  ;
61  import java.io.OutputStreamWriter  ;
62  import java.io.PrintWriter  ;
63  
64  import org.objectstyle.cayenne.util.Util;
65  
66  /**
67   * ProjectFile is an adapter from an object in Cayenne project
68   * to its representation in the file system.
69   * 
70   * @author Andrei Adamchik
71   */
72  public abstract class ProjectFile {
73  
74      protected String   location;
75      protected File   tempFile;
76      protected Project projectObj;
77  
78      public ProjectFile() {}
79  
80      /**
81       * Constructor for ProjectFile.
82       */
83      public ProjectFile(Project project, String   location) {
84          this.location = location;
85          this.projectObj = project;
86      }
87  
88      /**
89       * Builds a filename from the object name and "file suffix".
90       */
91      public String   getLocation() {
92          String   oName = getObjectName();
93          if (oName == null) {
94              throw new NullPointerException  ("Null name.");
95          }
96  
97          return oName + getLocationSuffix();
98      }
99  
100     /**
101     * Returns saved location of a file.
102     */
103     public String   getOldLocation() {
104         return location;
105     }
106 
107     /**
108      * Returns suffix to append to object name when 
109      * creating a file name. Default implementation 
110      * returns empty string.
111      */
112     public String   getLocationSuffix() {
113         return "";
114     }
115 
116     /**
117      * Returns a project object associated with this file.
118      */
119     public abstract Object   getObject();
120 
121     /**
122      * Returns a name of associated object, that is also 
123      * used as a file name.
124      */
125     public abstract String   getObjectName();
126 
127     /**
128      * Saves an underlying object to the file. 
129      * The procedure is dependent on the type of
130      * object and is implemented by concrete subclasses.
131      */
132     public abstract void save(PrintWriter   out) throws Exception  ;
133 
134     /**
135      * Returns true if this file wrapper can handle a
136      * specified object.
137      */
138     public abstract boolean canHandle(Object   obj);
139     
140    /**
141      * Returns true if this file wrapper can handle an
142      * internally stored object.
143      */
144     public boolean canHandleObject() {
145         return canHandle(getObject());
146     }
147 
148     /**
149      * Replaces internally stored filename with the current object name.
150      */
151     public void synchronizeLocation() {
152         location = getLocation();
153     }
154 
155     /**
156      * This method is called by project to let file know that
157      * it will be saved. Default implementation is a noop.
158      */
159     public void willSave() {}
160 
161     /**
162      * Saves ProjectFile's underlying object to a temporary 
163      * file, returning this file to the caller. If any problems are 
164      * encountered during saving, an Exception is thrown.
165      */
166     public void saveTemp() throws Exception   {
167         // cleanup any previous temp files
168         if (tempFile != null && tempFile.isFile()) {
169             tempFile.delete();
170             tempFile = null;
171         }
172 
173         // check write permissions for the target final file...
174         File   finalFile = resolveFile();
175         checkWritePermissions(finalFile);
176 
177         // ...but save to temp file first
178         tempFile = tempFileForFile(finalFile);
179         
180         // must encode as UTF-8 - a default used by all Cayenne XML files
181         FileOutputStream   fout = new FileOutputStream  (tempFile);
182         OutputStreamWriter   fw = new OutputStreamWriter  (fout, "UTF-8");
183 
184         try {
185             PrintWriter   pw = new PrintWriter  (fw);
186             try {
187                 save(pw);
188             } finally {
189                 pw.close();
190             }
191         } finally {
192             fw.close();
193         }
194     }
195 
196     /**
197      * Returns a file which is a canonical representation of the 
198      * file to store a wrapped object. If an object was renamed, 
199      * the <b>new</b> name is returned.
200      */
201     public File   resolveFile() {
202         return getProject().resolveFile(getLocation());
203     }
204 
205     /**
206      * Returns a file which is a canonical representation of the 
207      * file to store a wrapped object. If an object was renamed, 
208      * the <b>old</b> name is returned. Returns null if this file 
209      * has never been saved before. 
210      */
211     public File   resolveOldFile() {
212         String   oldLocation = getOldLocation();
213         return (oldLocation != null) ? getProject().resolveFile(oldLocation) : null;
214     }
215 
216     /**
217      * Finishes saving the underlying object.
218      */
219     public File   saveCommit() throws ProjectException {
220         File   finalFile = resolveFile();
221         
222         if (tempFile != null) {
223             if (finalFile.exists()) {
224                 if (!finalFile.delete()) {
225                     throw new ProjectException(
226                         "Unable to remove old master file : " + finalFile);
227                 }
228             }
229 
230             if (!tempFile.renameTo(finalFile)) {
231                 throw new ProjectException(
232                     "Unable to move " + tempFile + " to " + finalFile);
233             }
234 
235             tempFile = null;
236         }
237         
238         return finalFile;
239     }
240 
241     /**
242      * Cleans up after unsuccessful or canceled save attempt.
243      */
244     public void saveUndo() {
245         if (tempFile != null && tempFile.isFile()) {
246             tempFile.delete();
247             tempFile = null;
248         }
249     }
250 
251     /**
252       * Returns the project.
253       * @return Project
254       */
255     public Project getProject() {
256         return projectObj;
257     }
258 
259     public boolean isRenamed() {
260         return !Util.nullSafeEquals(location, getLocation());
261     }
262 
263     /** 
264      * Creates a temporary file for the master file.
265      */
266     protected File   tempFileForFile(File   f) throws IOException   {
267         File   parent = f.getParentFile();
268         String   name = f.getName();
269 
270         if (name == null || name.length() < 3) {
271             name = "cayenne-project";
272         }
273  
274         if(!parent.exists()) {
275             if(!parent.mkdirs()) {
276                 throw new IOException  ("Error creating directory tree: " + parent);
277             }
278         }
279          
280         return File.createTempFile(name, null, parent);
281     }
282 
283     protected void checkWritePermissions(File   file) throws IOException   {
284         if (file.isDirectory()) {
285             throw new IOException  ("Target file is a directory: " + file);
286         }
287 
288         if (file.exists() && !file.canWrite()) {
289             throw new IOException  ("Can't write to file: " + file);
290         }
291     }
292 
293     public String   toString() {
294         StringBuffer   buf = new StringBuffer  ();
295         buf.append("ProjectFile [").append(getClass().getName()).append("]: name = ");
296         if (getObject() != null) {
297             buf.append("*null*");
298         } else {
299             buf.append(getObjectName());
300         }
301 
302         return buf.toString();
303     }
304 }
305
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