MetaData


1   /*******************************************************************************
2    * Copyright (c) 2003, 2005 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    * 
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  
12  package org.eclipse.osgi.framework.internal.defaultadaptor;
13  
14  import java.io.*;
15  import java.util.Properties  ;
16  
17  /**
18   * This class uses a Properties object to store and get MetaData information.  
19   * All data is converted into String data before saving.
20   */
21  public class MetaData {
22  
23      /**
24       * The Properties file to store the data.
25       */
26      Properties   properties = new Properties  ();
27  
28      /**
29       * The File object to store and load the Properties object.
30       */
31      File datafile;
32  
33      /**
34       * The header string to use when storing data to the datafile.
35       */
36      String   header;
37  
38      /**
39       * Constructs a MetaData object that uses the datafile to persistently
40       * store data.
41       * @param datafile The File object used to persistently load and store data.
42       * @param header The header to use when storing data persistently.
43       */
44      public MetaData(File datafile, String   header) {
45          this.datafile = datafile;
46          this.header = header;
47      }
48  
49      /**
50       * Gets the metadata value for the key.
51       * @param key the key of the metadata
52       * @param def the default value to return if the key does not exist
53       * @return the value of the metadata or null if the key does not exist
54       * and the specified default is null.
55       */
56      public String   get(String   key, String   def) {
57          return properties.getProperty(key, def);
58      }
59  
60      /**
61       * Gets the integer value for the key.
62       * @param key the key of the metadata
63       * @param def the default value to return if the key does not exist
64       * @return the value of the metadata; if the key does not exist or
65       * the value cannot be converted to an int value then the
66       * specified default value is returned.
67       */
68      public int getInt(String   key, int def) {
69          String   result = get(key, null);
70          if (result == null) {
71              return def;
72          }
73          try {
74              return Integer.parseInt(result);
75          } catch (NumberFormatException   nfe) {
76              return def;
77          }
78      }
79  
80      /**
81       * Gets the long value for the key.
82       * @param key the key of the metadata
83       * @param def the default value to return if the key does not exist
84       * @return the value of the metadata; if the key does not exist or
85       * the value cannot be converted to an long value then the
86       * specified default value is returned.
87       */
88      public long getLong(String   key, long def) {
89          String   result = get(key, null);
90          if (result == null) {
91              return def;
92          }
93          try {
94              return Long.parseLong(result);
95          } catch (NumberFormatException   nfe) {
96              return def;
97          }
98      }
99  
100     /**
101      * Gets the boolean value for the key.
102      * @param key the key of the metadata
103      * @param def the default value to return if the key does not exist
104      * @return the value of the metadata; if the key does not exist then the
105      * specified default value is returned.
106      */
107     public boolean getBoolean(String   key, boolean def) {
108         String   result = get(key, null);
109         if (result == null) {
110             return def;
111         }
112         return Boolean.valueOf(result).booleanValue();
113     }
114 
115     /**
116      * Sets the String value for a key.
117      * @param key the key of the metadata
118      * @param val the value of the metadata
119      */
120     public void set(String   key, String   val) {
121         properties.put(key, val);
122     }
123 
124     /**
125      * Sets the int value for a key.
126      * @param key the key of the metadata
127      * @param val the value of the metadata
128      */
129     public void setInt(String   key, int val) {
130         properties.put(key, Integer.toString(val));
131     }
132 
133     /**
134      * Sets the long value for a key.
135      * @param key the key of the metadata
136      * @param val the value of the metadata
137      */
138     public void setLong(String   key, long val) {
139         properties.put(key, Long.toString(val));
140     }
141 
142     /**
143      * Sets the boolean value for a key.
144      * @param key the key of the metadata
145      * @param val the value of the metadata
146      */
147     public void setBoolean(String   key, boolean val) {
148         properties.put(key, new Boolean  (val).toString());
149     }
150 
151     /**
152      * Removes the metadata value with the specified key.
153      * @param key the key of the metadata to be removed
154      */
155     public void remove(String   key) {
156         properties.remove(key);
157     }
158 
159     /**
160      * Saves the metadata to persistent storage.
161      * @throws IOException if there is a problem saving to persistent storage.
162      */
163     public void save() throws IOException {
164         if (!datafile.exists() && datafile.getParent() != null) {
165             File parent = new File(datafile.getParent());
166             if (!parent.exists())
167                 parent.mkdir();
168         }
169             
170         FileOutputStream fos = new FileOutputStream(datafile);
171         try {
172             properties.store(fos, header);
173         } finally {
174             fos.close();
175         }
176     }
177 
178     /**
179      * Loads the metadata from persistent storage
180      * @throws IOException if there is a problem reading from persistent storage.
181      */
182     public void load() throws IOException {
183         properties.clear();
184         if (datafile.exists()) {
185             FileInputStream fis = new FileInputStream(datafile);
186             try {
187                 properties.load(fis);
188             } finally {
189                 fis.close();
190             }
191         }
192     }
193 
194     /**
195      * @see Object#toString()
196      */
197     public String   toString() {
198         return properties.toString();
199     }
200 
201 }
202
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