tim/prune/save/xml/XmlUtils.java

   1 package tim.prune.save.xml;
   2
   3 import java.io.File;
   4 import java.io.FileOutputStream;
   5 import java.io.IOException;
   6 import java.io.OutputStreamWriter;
   7 import java.nio.charset.Charset;
   8
   9 /**
  10  * Collection of utility functions for handling XML
  11  */
  12 public abstract class XmlUtils
  13 {
  14         /** Start of Cdata sequence */
  15         private static final String CDATA_START = "<![CDATA[";
  16         /** End of Cdata sequence */
  17         private static final String CDATA_END = "]]>";
  18         /** Cached copy of system encoding string */
  19         private static String _systemEncoding = null;
  20
  21         /**
  22          * Fix the CDATA blocks in the given String to give valid xml
  23          * @param inString String to modify
  24          * @return fixed String
  25          */
  26         public static String fixCdata(String inString)
  27         {
  28                 if (inString == null) return "";
  29                 if (inString.indexOf('<') < 0 && inString.indexOf('>') < 0) {
  30                         return inString;
  31                 }
  32                 String result = inString;
  33                 // Remove cdata block at start if present
  34                 if (result.startsWith(CDATA_START)) {
  35                         result = result.substring(CDATA_START.length());
  36                 }
  37                 // Remove all instances of end block
  38                 result = result.replaceAll(CDATA_END, "");
  39                 // Now check whether cdata block is required
  40                 if (result.indexOf('<') < 0 && result.indexOf('>') < 0) {
  41                         return result;
  42                 }
  43                 return CDATA_START + result + CDATA_END;
  44         }
  45
  46
  47         /**
  48          * @return true if system uses UTF-8 by default
  49          */
  50         public static boolean isSystemUtf8()
  51         {
  52                 String systemEncoding = getSystemEncoding();
  53                 return (systemEncoding != null && systemEncoding.toUpperCase().equals("UTF-8"));
  54         }
  55
  56         /**
  57          * @return name of the system's character encoding
  58          */
  59         public static String getSystemEncoding()
  60         {
  61                 if (_systemEncoding == null) {
  62                         _systemEncoding = determineSystemEncoding();
  63                 }
  64                 return _systemEncoding;
  65         }
  66
  67         /**
  68          * Use a temporary file to obtain the name of the default system encoding
  69          * @return name of default system encoding, or null if write failed
  70          */
  71         private static String determineSystemEncoding()
  72         {
  73                 File tempFile = null;
  74                 String encoding = null;
  75                 try
  76                 {
  77                         tempFile = File.createTempFile("gpsprune", null);
  78                         OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(tempFile));
  79                         encoding = getEncoding(writer);
  80                         writer.close();
  81                 }
  82                 catch (IOException e) {} // value stays null
  83                 // Delete temp file
  84                 if (tempFile != null && tempFile.exists()) {
  85                         if (!tempFile.delete()) {
  86                                 System.err.println("Cannot delete temp file: " + tempFile.getAbsolutePath());
  87                         }
  88                 }
  89                 // If writing failed (eg permissions) then just ask system for default
  90                 if (encoding == null) encoding = Charset.defaultCharset().name();
  91                 return encoding;
  92         }
  93
  94
  95         /**
  96          * Get the default system encoding using a writer
  97          * @param inWriter writer object
  98          * @return string defining encoding
  99          */
 100         public static String getEncoding(OutputStreamWriter inWriter)
 101         {
 102                 String encoding = inWriter.getEncoding();
 103                 try {
 104                         encoding =  Charset.forName(encoding).name();
 105                 }
 106                 catch (Exception e) {} // ignore failure to find encoding
 107                 return encoding;
 108         }
 109 }