CBSystemProperties


1   package com.ca.commons.cbutil;
2   
3   import java.io.*;
4   import java.util.Enumeration  ;
5   import java.util.logging.*;
6   
7   /**
8    * <p>Sun, in their fairly limited wisdom, decided to disable
9    * the ability to get system environment variables in java.
10   * (Apart from a couple that they kindly decided to let through
11   * that are fairly useless).  Apparently it wasn't platform
12   * independent enough, and might have screwed up their revenue
13   * stream.  Or something.</p>
14   * <p/>
15   * <p>Anyway, this class contains a filthy hack to get the
16   * information anyway, come hell, Sun, or high water.
17   * basically it shells a 'set' command, and attempts to do
18   * this on both unix and windows.</p>
19   * <p/>
20   * <p>This is needed by some JX plugins, that rely on user-set system
21   * environment variables to do stuff.</p>
22   */
23  
24  public class CBSystemProperties
25  {
26      private static Logger log = Logger.getLogger(CBSystemProperties.class.getName());
27  
28      /**
29       * A simple minded test to see if we are running on a windows machine.
30       *
31       * @return true if on windows, false if not.
32       */
33  
34      public static boolean isWindows()
35      {
36          String   os = System.getProperty("os.name");
37          if (os != null && os.toLowerCase().indexOf("windows") > -1)
38          {
39              log.fine("this is a windows machine.");
40              return true;
41          }
42  
43          log.fine("this is a unix machine.");
44          return false;
45      }
46  
47  
48      /**
49       * This writes a file called 'runset.bat' (or 'runset.sh' on unix)
50       * that can then be 'exec'-ed to read the system property list.
51       *
52       * @param batchFileName - the name of the batch file to create, e.g. 'runset.bat' or 'runset.sh'
53       */
54  
55      private static void writeBatchFile(String   batchFileName)
56              throws IOException
57      {
58          File setBatch = new File(batchFileName);
59          
60          // only write the batch file once.
61          if (setBatch.exists() == false)
62          {
63              FileWriter out = new FileWriter(setBatch);
64              out.write("set", 0, 3);
65              out.flush();
66              out.close();
67          }
68      }
69  
70      /**
71       * Cleans up - deletes the batch file afterwards...
72       *
73       * @param batchFileName - the name of the batch file to delete, e.g. 'runset.bat' or 'runset.sh'
74       */
75  
76      private static void deleteBatchFile(String   batchFileName)
77      {
78          File setBatch = new File(batchFileName);
79          
80          // nb. - catch exception locally, since this is not
81          // fatal; if everything else has worked we probably 
82          // don't care if we can't clean up.
83          try
84          {
85              setBatch.delete();
86          }
87          catch (Exception   e)
88          {
89              log.log(Level.WARNING, "unable to delete batch file " + batchFileName, e);
90          }
91      }
92  
93      /**
94       * This takes the batch file generated by writeBatchFile() and
95       * exec()s it to read the system dependent list of properties.
96       * (which is then added to the java system properties list...)
97       *
98       * @param batchFileName - the name of the batch file to use, e.g. 'runset.bat' or 'runset.sh'
99       */
100 
101     private static void readSystemProperties(String   batchFileName)
102             throws IOException
103     {
104         // use the batch file...
105         Process   bloop = Runtime.getRuntime().exec(batchFileName);
106 
107         BufferedReader input = new BufferedReader(new InputStreamReader(bloop.getInputStream()));
108         BufferedReader errors = new BufferedReader(new InputStreamReader(bloop.getErrorStream()));
109         
110         // run through the batch file, spliting names and value on the '=' sign
111         // (e.g DXHOME=c:\dxserver => DXHOME  and 'c:\dxserver' )
112         
113         String   line = "";
114 
115         log.fine("reading output from batch file");
116 
117         setSystemPropertiesFromBufferedReader(input);
118 
119         while ((line = errors.readLine()) != null)
120         {
121             System.out.println("ERRORS: " + line);
122         }
123 
124 
125     }
126 
127     private static void setSystemPropertiesFromBufferedReader(BufferedReader input) throws IOException
128     {
129         String   line;
130         int pos;
131         String   name;
132         String   value;
133         while ((line = input.readLine()) != null)
134         {
135             log.finest("read raw line: " + line);
136 
137             if ((pos = line.indexOf('=')) > 0)
138             {
139                 name = line.substring(0, pos);
140                 if (line.length() > pos)
141                     value = line.substring(pos + 1).trim();
142                 else
143                     value = "";
144 
145 
146                 if (System.getProperty(name) == null)
147                 {
148                     System.setProperty(name, value);
149                     log.fine("SET setting property '" + name + "' equal '" + value + "'");
150                 }
151                 else
152                     log.fine("skipping existing value for: " + name);
153 
154             }
155         }
156     }
157 
158     /**
159      * for debugging - dumps the full system properties list at level 'fine' or better...
160      */
161 
162     // XXX can't figure out how to get the active level from Sun's logging library - so
163     // XXX we gather all the data before knowing if we want to log it.  *pffft*.
164     private static void dumpProperties()
165     {
166 
167         Enumeration   keys = System.getProperties().propertyNames();
168         while (keys.hasMoreElements())
169         {
170             String   key = (String  ) keys.nextElement();
171             log.fine("SYSPROPS: " + key + " : " + System.getProperty(key));
172         }
173     }
174 
175     /**
176      * This method relies on the system properties having been pre-written to
177      * a particular file (in the normal 'property=value' format used by both
178      * java properties files, and the results of 'set' on unix and windows).
179      * If it fails to find this property file, it will revert to trying to
180      * automatically run 'set' using the other 'loadSystemProperties()'
181      * method below.
182      */
183     public static boolean loadSystemProperties(File propertiesListFile)
184     {
185         if (propertiesListFile.exists() == false)
186         {
187             log.warning("Unable to find system properties file: '" + propertiesListFile.toString() + "' - attempting batch load instead");
188             return loadSystemProperties();
189         }
190 
191         try
192         {
193             setSystemPropertiesFromBufferedReader(new BufferedReader(new FileReader(propertiesListFile)));
194             dumpProperties();
195 
196             return true;
197         }
198         catch (IOException e)
199         {
200             log.log(Level.WARNING, "Error trying to load system properties file '" + propertiesListFile.toString() + "' - - attempting batch load instead.", e);
201             return loadSystemProperties();
202         }
203     }
204 
205     /**
206      * This method reads the system environment property list,
207      * and adds them directly to the System.getProperties()
208      * global property list.
209      *
210      * @return whether the operation was successfull, or
211      *         whether an error (usually an IOException) occurred.
212      */
213 
214     public static boolean loadSystemProperties()
215     {
216         try
217         {
218             // get a batch (or shell) script name
219             // nb - don't call it 'set.bat' -> fails on nt!
220             String   batchFileName = isWindows() ? "runset.bat" : "runset.sh";
221             
222             
223             // write it out with the single command 'set' inside...
224             writeBatchFile(batchFileName);
225             
226             // execute it, to read the system properties, and append
227             // them to the global system list...
228             readSystemProperties(batchFileName);
229     
230             // for debugging, dump the list of read properties...
231             dumpProperties();
232                 
233             // cleanup - delete the file...
234             deleteBatchFile(batchFileName);
235 
236             return true;
237         }
238         catch (Exception   e)
239         {
240             log.log(Level.SEVERE, "Error reading system properties...\n", e);
241             // In this case calling programs should either make 
242             // inspired guesses, or prompt users for missing values.
243             
244             return false;
245         }
246     }
247 
248     /**
249      * Main method for stand alone testing.
250      *
251      * @param argsv - not used.
252      */
253 
254     public static void main(String   argsv[])
255     {
256         log.addHandler(new ConsoleHandler());
257         log.setLevel(Level.FINEST);
258         log.fine("CBSystemProperties log active");
259 
260         loadSystemProperties();
261     }
262 
263 }
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