Version 18.2, December 2015

[GpsPrune.git] / tim / prune / save / xml / XmlUtils.java

diff --git a/tim/prune/save/xml/XmlUtils.java b/tim/prune/save/xml/XmlUtils.java
index a4f9caec11704a46dcd56fe3d22bde4922a49f09..3943d078de1c1166e708a15345989df0ef7fc428 100644 (file)
--- a/tim/prune/save/xml/XmlUtils.java
+++ b/tim/prune/save/xml/XmlUtils.java
@@ -1,5 +1,11 @@
 package tim.prune.save.xml;
 
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.nio.charset.Charset;
+
 /**
  * Collection of utility functions for handling XML
  */
@@ -9,6 +15,8 @@ public abstract class XmlUtils
        private static final String CDATA_START = "<![CDATA[";
        /** End of Cdata sequence */
        private static final String CDATA_END = "]]>";
+       /** Cached copy of system encoding string */
+       private static String _systemEncoding = null;
 
        /**
         * Fix the CDATA blocks in the given String to give valid xml
@@ -17,8 +25,8 @@ public abstract class XmlUtils
         */
        public static String fixCdata(String inString)
        {
-               if (inString == null) return "";
-               if (inString.indexOf('<') < 0 && inString.indexOf('>') < 0) {
+               if (inString == null || inString.isEmpty()) return "";
+               if (!hasIllegalCharacter(inString)) {
                        return inString;
                }
                String result = inString;
@@ -29,9 +37,93 @@ public abstract class XmlUtils
                // Remove all instances of end block
                result = result.replaceAll(CDATA_END, "");
                // Now check whether cdata block is required
-               if (result.indexOf('<') < 0 && result.indexOf('>') < 0) {
+               if (!XmlUtils.hasIllegalCharacter(result)) {
                        return result;
                }
                return CDATA_START + result + CDATA_END;
        }
+
+       /**
+        * Checks the input string for the three illegal characters,
+        * but only looping through the string once instead of three times
+        * @param inValue string to check
+        * @return true if at least one of the illegal characters is found
+        */
+       public static boolean hasIllegalCharacter(String inValue)
+       {
+               if (inValue == null) return false;
+               final int numChars = inValue.length();
+               for (int i=0; i<numChars; i++)
+               {
+                       final char c = inValue.charAt(i);
+                       if (c == '<' || c == '>' || c == '&')
+                       {
+                               return true;
+                       }
+               }
+               return false;
+       }
+
+       /**
+        * @return true if system uses UTF-8 by default
+        */
+       public static boolean isSystemUtf8()
+       {
+               String systemEncoding = getSystemEncoding();
+               return (systemEncoding != null && systemEncoding.toUpperCase().equals("UTF-8"));
+       }
+
+       /**
+        * @return name of the system's character encoding
+        */
+       public static String getSystemEncoding()
+       {
+               if (_systemEncoding == null) {
+                       _systemEncoding = determineSystemEncoding();
+               }
+               return _systemEncoding;
+       }
+
+       /**
+        * Use a temporary file to obtain the name of the default system encoding
+        * @return name of default system encoding, or null if write failed
+        */
+       private static String determineSystemEncoding()
+       {
+               File tempFile = null;
+               String encoding = null;
+               try
+               {
+                       tempFile = File.createTempFile("gpsprune", null);
+                       OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream(tempFile));
+                       encoding = getEncoding(writer);
+                       writer.close();
+               }
+               catch (IOException e) {} // value stays null
+               // Delete temp file
+               if (tempFile != null && tempFile.exists()) {
+                       if (!tempFile.delete()) {
+                               System.err.println("Cannot delete temp file: " + tempFile.getAbsolutePath());
+                       }
+               }
+               // If writing failed (eg permissions) then just ask system for default
+               if (encoding == null) encoding = Charset.defaultCharset().name();
+               return encoding;
+       }
+
+
+       /**
+        * Get the default system encoding using a writer
+        * @param inWriter writer object
+        * @return string defining encoding
+        */
+       public static String getEncoding(OutputStreamWriter inWriter)
+       {
+               String encoding = inWriter.getEncoding();
+               try {
+                       encoding =  Charset.forName(encoding).name();
+               }
+               catch (Exception e) {} // ignore failure to find encoding
+               return encoding;
+       }
 }