Native JDK code to copy files

Question

Is there a native JDK code to copy files(buffers, streams, or whatever)?

Answer 1

Your best option is to use Java NIO:

http://java.sun.com/javase/6/docs/api/java/nio/package-summary.html

For buffers see:

http://java.sun.com/javase/6/docs/api/java/nio/package-summary.html#buffers

For stream however, see the following article:

http://java.sun.com/docs/books/tutorial/essential/io/file.html#readStream

There are frameworks built on top of this, namely Mina and Netty:

• Mina - http://mina.apache.org/
• Netty - http://www.jboss.org/netty

Answer 2

If by "native" you mean "part of the Java standard API" (rather than platform-dependant code, which is usually called "native" in the Java world) and by "copy files" you mean "single method that takes a file and a target path and produces a copy of the file's contents" then no, there is no such method in the standard API. You have to open an InputStream and an OutputStream (optionally get their more efficient FileChannels) and use a buffer to transfer bytes. Convenient single methods to call are found in Apache Commons IO.

Answer 3

This is the preferred way to copy a file since JDK 1.4 and later

public static void copyFile(final File sourceFile, final File destFile) throws IOException
{
    if (!destFile.exists())
    {
        destFile.createNewFile();
    }

    FileChannel source = null;
    FileChannel destination = null;
    try
    {
        source = new FileInputStream(sourceFile).getChannel();
        destination = new FileOutputStream(destFile).getChannel();
        destination.transferFrom(source, 0, source.size());
    }
    finally
    {
       source.close();
       destination.close();
    }
}

public abstract long transferFrom(ReadableByteChannel src, long position, long count) throws IOException

... This method is potentially much more efficient than a simple loop that reads from this channel and writes to the target channel. Many operating systems can transfer bytes directly from the filesystem cache to the target channel without actually copying them. ...