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         /** File to cache */
  16         private File _file = null;
  17         /** Array to hold lines of file */
  18         private String[] _contentArray = null;
  19
  20
  21         /**
  22          * Constructor
  23          * @param inFile File object to cache
  24          */
  25         public FileCacher(File inFile)
  26         {
  27                 _file = inFile;
  28                 loadFile();
  29         }
  30
  31
  32         /**
  33          * Load the specified file into memory
  34          */
  35         private void loadFile()
  36         {
  37                 ArrayList<String> contentList = new ArrayList<String>();
  38                 if (_file != null && _file.exists() && _file.canRead())
  39                 {
  40                         BufferedReader reader = null;
  41                         try
  42                         {
  43                                 reader = new BufferedReader(new FileReader(_file));
  44                                 String currLine = reader.readLine();
  45                                 while (currLine != null)
  46                                 {
  47                                         if (currLine.trim().length() > 0)
  48                                                 contentList.add(currLine);
  49                                         currLine = reader.readLine();
  50                                 }
  51                         }
  52                         catch (IOException ioe) {}
  53                         finally
  54                         {
  55                                 // close file ignoring errors
  56                                 try
  57                                 {
  58                                         if (reader != null) reader.close();
  59                                 }
  60                                 catch (Exception e) {}
  61                         }
  62                 }
  63                 // Convert into String array for keeps
  64                 int numLines = contentList.size();
  65                 _contentArray = new String[numLines];
  66                 for (int i=0; i<numLines; i++)
  67                         _contentArray[i] = contentList.get(i);
  68         }
  69
  70
  71         /**
  72          * @return Contents of the file as array of non-blank Strings
  73          */
  74         public String[] getContents()
  75         {
  76                 return _contentArray;
  77         }
  78
  79
  80         /**
  81          * Get the top section of the file for preview
  82          * @param inNumRows number of lines to extract
  83          * @param inMaxWidth max length of Strings (longer ones will be chopped)
  84          * @return String array containing non-blank lines from the file
  85          */
  86         public String[] getSnippet(int inNumRows, int inMaxWidth)
  87         {
  88                 final int MIN_SNIPPET_SIZE = 3;
  89                 // Check size is within sensible limits
  90                 int numToCopy = inNumRows;
  91                 if (numToCopy > getNumLines()) numToCopy = getNumLines();
  92                 int size = numToCopy;
  93                 if (size < MIN_SNIPPET_SIZE) size = MIN_SNIPPET_SIZE;
  94                 String[] result = new String[size];
  95                 // Copy Strings across
  96                 System.arraycopy(_contentArray, 0, result, 0, numToCopy);
  97                 // Chop Strings to max width if necessary
  98                 if (inMaxWidth > 10)
  99                 {
 100                         for (int i=0; i<size; i++)
 101                         {
 102                                 if (result[i] == null)
 103                                         result[i] = "";
 104                                 else
 105                                 {
 106                                         if (result[i].length() > inMaxWidth)
 107                                                 result[i] = result[i].trim();
 108                                         if (result[i].length() > inMaxWidth)
 109                                                 result[i] = result[i].substring(0, inMaxWidth);
 110                                 }
 111                         }
 112                 }
 113                 return result;
 114         }
 115
 116         /**
 117          * @return the number of non-blank lines in the file
 118          */
 119         public int getNumLines()
 120         {
 121                 return _contentArray.length;
 122         }
 123
 124
 125         /**
 126          * Clear the memory
 127          */
 128         public void clear()
 129         {
 130                 _file = null;
 131                 _contentArray = null;
 132         }
 133 }