PropertiesUtil


1   // Copyright (c) 2003-2007, Jodd Team (jodd.sf.net). All Rights Reserved.
2   
3   package jodd.util;
4   
5   import java.io.File  ;
6   import java.io.FileInputStream  ;
7   import java.io.FileOutputStream  ;
8   import java.io.IOException  ;
9   import java.util.Iterator  ;
10  import java.util.Properties  ;
11  
12  /**
13   * Misc java.util.Properties utils.
14   */
15  public class PropertiesUtil {
16  
17      // ---------------------------------------------------------------- to/from files
18  
19      /**
20       * Create properties from the file.
21       *
22       * @param fileName properties file name to load
23       *
24       * @exception IOException
25       */
26      public static Properties   createFromFile(String   fileName) throws IOException   {
27          return createFromFile(new File  (fileName));
28      }
29  
30      /**
31       * Create properties from the file.
32       *
33       * @param file properties file to load
34       *
35       * @exception IOException
36       */
37      public static Properties   createFromFile(File   file) throws IOException   {
38          Properties   prop = new Properties  ();
39          loadFromFile(prop, file);
40          return prop;
41      }
42  
43      /**
44       * Loads properties from the file. Properties are appended to the existing
45       * properties object.
46       *
47       * @param p        properties to fill in
48       * @param fileName properties file name to load
49       *
50       * @exception IOException
51       */
52      public static void loadFromFile(Properties   p, String   fileName) throws IOException   {
53          loadFromFile(p, new File  (fileName));
54      }
55  
56      /**
57       * Loads properties from the file. Properties are appended to the existing
58       * properties object.
59       *
60       * @param p      properties to fill in
61       * @param file   file to read properties from
62       *
63       * @exception IOException
64       */
65      public static void loadFromFile(Properties   p, File   file) throws IOException   {
66          FileInputStream   fis = null;
67          try {
68              fis = new FileInputStream  (file);
69              p.load(fis);
70          } finally {
71              if (fis != null) {
72                  fis.close();
73              }
74          }
75      }
76  
77  
78      /**
79       * Writes properties to a file.
80       *
81       * @param p        properties to write to file
82       * @param fileName destination file name
83       *
84       * @exception IOException
85       */
86      public static void writeToFile(Properties   p, String   fileName) throws IOException   {
87          writeToFile(p, new File  (fileName), null);
88      }
89  
90      /**
91       * Writes properties to a file.
92       *
93       * @param p        properties to write to file
94       * @param fileName destiantion file name
95       * @param header   optional header
96       *
97       * @exception IOException
98       */
99      public static void writeToFile(Properties   p, String   fileName, String   header) throws IOException   {
100         writeToFile(p, new File  (fileName), header);
101     }
102 
103     /**
104      * Writes properties to a file.
105      *
106      * @param p      properties to write to file
107      * @param file   destination file
108      *
109      * @exception IOException
110      */
111     public static void writeToFile(Properties   p, File   file) throws IOException   {
112         writeToFile(p, file, null);
113     }
114 
115     /**
116      * Writes properties to a file.
117      *
118      * @param p      properties to write to file
119      * @param file   destiantion file
120      * @param header optional header
121      *
122      * @exception IOException
123      */
124     public static void writeToFile(Properties   p, File   file, String   header) throws IOException   {
125         FileOutputStream   fos = null;
126         try {
127             fos = new FileOutputStream  (file);
128             p.store(fos, header);
129         } finally {
130             if (fos != null) {
131                 fos.close();
132             }
133         }
134     }
135 
136 
137     // ---------------------------------------------------------------- subsets
138 
139     /**
140      * Creates new Properties object from the original one, by copying
141      * those properties that have specified first part of the key name.
142      * Prefix may be optionally stripped during this process.
143      *
144      * @param p         source properties, from which new object will be created
145      * @param prefix    key names prefix 
146      *
147      * @return subset properties
148      */
149     public static Properties   subset(Properties   p, String   prefix, boolean stripPrefix) {
150         if (StringUtil.isBlank(prefix) == true) {
151             return p;
152         }
153         if (prefix.endsWith(".") == false) {
154             prefix += '.';
155         }
156         Properties   result = new Properties  ();
157         int baseLen = prefix.length();
158         Iterator   iti = p.keySet().iterator();
159         while (iti.hasNext()) {
160             String   key = (String  ) iti.next();
161             if (key.startsWith(prefix) == true) {
162                 result.setProperty(stripPrefix == true ? key.substring(baseLen) : key, p.getProperty(key));
163             }
164         }
165         return result;
166     }
167 
168 }
169
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