add a public static void main method to list and optional extract the individual files from a compound. The original code was proposed by Garrett Rooney.

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@150723 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/lucene/index/CompoundFileReader.java

@@ -17,12 +17,16 @@ package org.apache.lucene.index;
  */
 
 import org.apache.lucene.store.Directory;
+import org.apache.lucene.store.FSDirectory;
 import org.apache.lucene.store.IndexInput;
 import org.apache.lucene.store.BufferedIndexInput;
 import org.apache.lucene.store.IndexOutput;
 import org.apache.lucene.store.Lock;
+
+import java.util.Arrays;
 import java.util.HashMap;
 import java.io.IOException;
+import java.io.FileOutputStream;
 
 
 /**
@@ -234,4 +238,82 @@ class CompoundFileReader extends Directory {
 
 
     }
+
+    /**
+     * Prints the filename and size of each file within a given compound file.
+     * Add the -extract flag to extract files to the current working directory.
+     * In order to make the extracted version of the index work, you have to copy
+     * the segments file from the compound index into the directory where the extracted files are stored.
+     * @param args
+     */
+    public static void main(String [] args) {
+      String dirname = null, filename = null;
+      boolean extract = false;
+
+      for (int i = 0; i < args.length; ++i) {
+        if (args[i].equals("-extract")) {
+          extract = true;
+        } else if (dirname == null) {
+          dirname = args[i];
+        } else if (filename == null) {
+          filename = args[i];
+        }
+      }
+
+      if (dirname == null || filename == null) {
+        System.out.println("Usage: CompoundFileReader [-extract] <directory> <cfsfile>");
+        return;
+      }
+
+      Directory dir = null;
+      CompoundFileReader cfr = null;
+        
+      try {
+        dir = FSDirectory.getDirectory(dirname, false);
+
+        cfr = new CompoundFileReader(dir, filename);
+
+        String [] files = cfr.list();
+        Arrays.sort(files);   // sort the array of filename so that the output is more readable
+        
+        for (int i = 0; i < files.length; ++i) {
+          long len = cfr.fileLength(files[i]);
+
+          if (extract) {
+            System.out.println("extract " + files[i] + " with " + len + " bytes to local directory...");
+            IndexInput ii = cfr.openInput(files[i]);
+
+            FileOutputStream f = new FileOutputStream(files[i]);
+            
+            // read and write with a small buffer, which is more effectiv than reading byte by byte
+            byte[] buffer = new byte[1024];
+            int chunk = buffer.length;
+            while(len > 0) {
+              final int bufLen = (int) Math.min(chunk, len);
+              ii.readBytes(buffer, 0, bufLen);
+              f.write(buffer, 0, bufLen);
+              len -= bufLen;
+            }
+            
+            f.close();
+            ii.close();
+          }
+          else
+            System.out.println(files[i] + ": " + len + " bytes");
+        }
+      } catch (IOException ioe) {
+        ioe.printStackTrace();
+      }
+      finally {
+        try {
+          if (dir != null)
+            dir.close();
+          if (cfr != null)
+            cfr.close();
+        }
+        catch (IOException ioe) {
+          ioe.printStackTrace();
+        }
+      }
+    }
 }