Reha/src/systemTools/FileComparator.java

   1 package systemTools;
   2
   3 import java.io.File;
   4 import java.io.FileInputStream;
   5 import java.io.IOException;
   6 import java.nio.ByteBuffer;
   7 import java.nio.channels.FileChannel;
   8
   9
  10             public class FileComparator implements FileNIONonDirectBufComparato {
  11                 int bufferSize;
  12                 ByteBuffer buffer1;
  13                 ByteBuffer buffer2;
  14
  15                 public FileComparator(int bufferSize) {
  16                     this.bufferSize = bufferSize;
  17                     buffer1 = ByteBuffer.allocate(bufferSize);
  18                     buffer2 = ByteBuffer.allocate(bufferSize);
  19                     //System.out.println("Using: java.nio with non direct byte-buffers of size " + bufferSize + " bytes");
  20                 }
  21
  22                 private int readIn(FileChannel f, ByteBuffer buffer) throws IOException {
  23                     int x = 0, z = 0;
  24                     do {
  25                         x+=z;
  26                         z = f.read(buffer);
  27                     } while ((x < bufferSize) & (z != -1));
  28                     return x;
  29                 }
  30
  31                 private static boolean compare(ByteBuffer a, ByteBuffer b, int len) {
  32                     for(int i = 0; i < len; i++) if (a.get(i) != b.get(i)) return false;
  33                     return true;
  34                 }
  35
  36                 public int compareFiles(File source1, File source2) throws IOException {
  37                     FileInputStream s1 = null, s2 = null;
  38                     long source1Size = source1.length();
  39                     long source2Size = source2.length();
  40                     if (source1Size != source2Size) return 1;
  41                     try {
  42                         s1 = new FileInputStream(source1);
  43                         s2 = new FileInputStream(source2);
  44                         long alreadyReadedBytes = 0;
  45
  46                         while (alreadyReadedBytes < source1Size) {
  47                             buffer1.clear();
  48                             buffer2.clear();
  49                             int size1 = readIn(s1.getChannel(), buffer1);
  50                             /*int size2 = */readIn(s2.getChannel(), buffer2);
  51                             //assert (size1 != size2) :"Files have different sizes in contradiction to earlier check";
  52                             if (!compare(buffer1, buffer2, size1)){
  53
  54                                 return 2;
  55                             }
  56                             alreadyReadedBytes += size1;
  57                         }
  58                         return 0;
  59                     } finally {
  60                         if (s1 != null) s1.close();
  61                         if (s2 != null) s2.close();
  62                     }
  63                 }
  64             }
  65 //public interface FileNIONonDirectBufComparator {
  66
  67             interface FileNIONonDirectBufComparato {
  68                 public int compareFiles(File source1, File source2) throws IOException;
  69                 }
  70