Difference between revisions of "Copy a file"

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* Original Source: [http://javaalmanac.com/egs/java.io/pkg.html?l=rel#Files The Java Developers Almanac 1.4]
 
* Original Source: [http://javaalmanac.com/egs/java.io/pkg.html?l=rel#Files The Java Developers Almanac 1.4]
  
Copies or moves a file without a loop.  Although I'm not certain, I believe using a FileChannel allows the OS to short-circuit the operation (without actually transferring the data through Java code).
+
Copies or moves a file without a loop.  Although I'm not sure, I believe using a FileChannel allows the OS to short-circuit the operation (without actually transferring the data through Java code).
  
 
<HIGHLIGHTSYNTAX>
 
<HIGHLIGHTSYNTAX>
     public void move(File src, File dest, boolean move) throws Exception {
+
     public void copy(File src, File dest, boolean move) throws Exception {
 
// Create channel on the source
 
// Create channel on the source
 
         FileChannel srcChannel = new FileInputStream(src).getChannel();
 
         FileChannel srcChannel = new FileInputStream(src).getChannel();

Revision as of 23:43, 23 February 2007

Implementations

Java

    // Copies src file to dst file.
    // If the dst file does not exist, it is created
    void copy(File src, File dst) throws IOException {
        InputStream in = new FileInputStream(src);
        OutputStream out = new FileOutputStream(dst);
    
        // Transfer bytes from in to out
        byte[] buf = new byte[1024];
        int len;
        while ((len = in.read(buf)) > 0) {
            out.write(buf, 0, len);
        }
        in.close();
        out.close();
    }

Copies or moves a file without a loop. Although I'm not sure, I believe using a FileChannel allows the OS to short-circuit the operation (without actually transferring the data through Java code).

<HIGHLIGHTSYNTAX>

   public void copy(File src, File dest, boolean move) throws Exception {

// Create channel on the source

       FileChannel srcChannel = new FileInputStream(src).getChannel();
   	// Create channel on the destination
   	FileChannel dstChannel = new FileOutputStream(dest).getChannel();
   
   	// Copy file contents from source to destination

dstChannel.transferFrom(srcChannel, 0, srcChannel.size());

   	// Close the channels

srcChannel.close();

       dstChannel.close();
       if(move) src.delete();	
   }

</HIGHLIGHTSYNTAX>