tim/prune/load/FileCacher.java

   1 package tim.prune.load;
   2
   3 import java.io.BufferedReader;
   4 import java.io.File;
   5 import java.io.FileReader;
   6 import java.io.IOException;
   7 import java.util.ArrayList;
   8
   9 /**
  10  * Class to load the contents of a file
  11  * into an array for later retrieval
  12  */
  13 public class FileCacher
  14 {
  15         private File _file = null;
  16         private String[] _contentArray = null;
  17
  18
  19         /**
  20          * Constructor
  21          * @param inFile File object to cache
  22          */
  23         public FileCacher(File inFile)
  24         {
  25                 _file = inFile;
  26                 loadFile();
  27         }
  28
  29
  30         /**
  31          * Load the specified file into memory
  32          */
  33         private void loadFile()
  34         {
  35                 ArrayList contentList = new ArrayList();
  36                 if (_file != null && _file.exists() && _file.canRead())
  37                 {
  38                         BufferedReader reader = null;
  39                         try
  40                         {
  41                                 reader = new BufferedReader(new FileReader(_file));
  42                                 String currLine = reader.readLine();
  43                                 while (currLine != null)
  44                                 {
  45                                         if (currLine.trim().length() > 0)
  46                                                 contentList.add(currLine);
  47                                         currLine = reader.readLine();
  48                                 }
  49                         }
  50                         catch (IOException ioe) {}
  51                         finally
  52                         {
  53                                 // close file ignoring errors
  54                                 try
  55                                 {
  56                                         if (reader != null) reader.close();
  57                                 }
  58                                 catch (Exception e) {}
  59                         }
  60                 }
  61                 // Convert into String array for keeps
  62                 int numLines = contentList.size();
  63                 _contentArray = new String[numLines];
  64                 for (int i=0; i<numLines; i++)
  65                         _contentArray[i] = contentList.get(i).toString();
  66         }
  67
  68
  69         /**
  70          * @return Contents of the file as array of non-blank Strings
  71          */
  72         public String[] getContents()
  73         {
  74                 return _contentArray;
  75         }
  76
  77
  78         /**
  79          * Get the top section of the file for preview
  80          * @param inNumRows number of lines to extract
  81          * @param inMaxWidth max length of Strings (longer ones will be chopped)
  82          * @return String array containing non-blank lines from the file
  83          */
  84         public String[] getSnippet(int inNumRows, int inMaxWidth)
  85         {
  86                 final int MIN_SNIPPET_SIZE = 3;
  87                 // Check size is within sensible limits
  88                 int numToCopy = inNumRows;
  89                 if (numToCopy > getNumLines()) numToCopy = getNumLines();
  90                 int size = numToCopy;
  91                 if (size < MIN_SNIPPET_SIZE) size = MIN_SNIPPET_SIZE;
  92                 String[] result = new String[size];
  93                 // Copy Strings across
  94                 System.arraycopy(_contentArray, 0, result, 0, numToCopy);
  95                 // Chop Strings to max width if necessary
  96                 if (inMaxWidth > 10)
  97                 {
  98                         for (int i=0; i<size; i++)
  99                         {
 100                                 if (result[i] == null)
 101                                         result[i] = "";
 102                                 else
 103                                 {
 104                                         if (result[i].length() > inMaxWidth)
 105                                                 result[i] = result[i].trim();
 106                                         if (result[i].length() > inMaxWidth)
 107                                                 result[i] = result[i].substring(0, inMaxWidth);
 108                                 }
 109                         }
 110                 }
 111                 return result;
 112         }
 113
 114         /**
 115          * @return the number of non-blank lines in the file
 116          */
 117         public int getNumLines()
 118         {
 119                 return _contentArray.length;
 120         }
 121
 122
 123         /**
 124          * Clear the memory
 125          */
 126         public void clear()
 127         {
 128                 _file = null;
 129                 _contentArray = null;
 130         }
 131 }