Solved: copy file | Experts Exchange

just a note: it seems to me better to use directly Input/OutputStreams and byte[], instead of Reader&Writers & char[] ...

expertmb

this is another solution

import java.io.*;
public class FileCopy {
public static void copy(String source_name, String dest_name)
throws IOException
{
File source_file = new File(source_name);
File destination_file = new File(dest_name);
FileInputStream source = null;
FileOutputStream destination = null;
byte[] buffer;
int bytes_read;

try {
// First make sure the specified source file
// exists, is a file, and is readable.
if (!source_file.exists() || !source_file.isFile())
throw new FileCopyException("FileCopy: no such source file: " + source_name);
if (!source_file.canRead())
throw new FileCopyException("FileCopy: source file " +
"is unreadable: " + source_name);

// If the destination exists, make sure it is a writeable file
// and ask before overwriting it. If the destination doesn't
// exist, make sure the directory exists and is writeable.
if (destination_file.exists()) {
if (destination_file.isFile()) {
DataInputStream in = new DataInputStream(System.in);
String response;

if (!destination_file.canWrite())
throw new FileCopyException("FileCopy:
destination " +
"file is unwriteable: " + dest_name);

System.out.print("File " + dest_name +
" already exists. Overwrite? (Y/N): ");
System.out.flush();
response = in.readLine();
if (!response.equals("Y") && !response.equals("y"))
throw new FileCopyException("FileCopy: copy
cancelled.");
}
else
throw new FileCopyException("FileCopy: destination "
+ "is not a file: " + dest_name);
}
else {
File parentdir = parent(destination_file);
if (!parentdir.exists())
throw new FileCopyException("FileCopy: destination "
+ "directory doesn't exist: " +
dest_name);
if (!parentdir.canWrite())
throw new FileCopyException("FileCopy: destination "
+ "directory is unwriteable: " +
dest_name);
}

// If we've gotten this far, then everything is okay; we can
// copy the file.
source = new FileInputStream(source_file);
destination = new FileOutputStream(destination_file);
buffer = new byte[1024];
while(true) {
bytes_read = source.read(buffer);
if (bytes_read == -1) break;
destination.write(buffer, 0, bytes_read);
}
}
// No matter what happens, always close any streams we've
opened.
finally {
if (source != null)
try { source.close(); } catch (IOException e) { ; }
if (destination != null)
try { destination.close(); } catch (IOException e) { ; }
}
}

// File.getParent() can return null when the file is specified
without
// a directory or is in the root directory.
// This method handles those cases.
private static File parent(File f) {
String dirname = f.getParent();
if (dirname == null) {
if (f.isAbsolute()) return new File(File.separator);
else return new File(System.getProperty("user.dir"));
}
return new File(dirname);
}

public static void main(String[] args) {
if (args.length != 2)
System.err.println("Usage: java FileCopy " +
"<source file> <destination file>");
else {
try { copy(args[0], args[1]); }
catch (IOException e) {
System.err.println(e.getMessage()); }
}
}
}

class FileCopyException extends IOException {
public FileCopyException(String msg) { super(msg); }
}

mb...

akkaiah

     static public void execCmd(String[] cmdParam) throws Exception {
            StringBuffer cmd = new StringBuffer();
            cmd.append(cmdParam[0]).append(" ");

            for(int i = 1; i<cmdParam.length; i++) {
                  cmd.append(cmdParam[i]).append(" ");
            }

            Process pr = Runtime.getRuntime().exec(cmd.toString());
            pr.waitFor();
            Log.logMsg("Exit Value for :" + cmd + " is " + pr.exitValue());
}

call this method lie execCmd(" cmd.exe /c copy source destinaltion")

hope this helps..
Akkaiah

BradCox

The first solution hangs on zero-length files. With this change it doesn't.

int len;
while ((len = br.read(charBuff,0,fileLength)) > 0) bw.write(charBuff,0,len);

gforman

Using the new Java IO, this becomes very fast and simple:

/** Fast & simple file copy. */
public static void copy(File source, File dest) throws IOException {
      FileChannel in = null, out = null;
      try {
            in = new FileInputStream(source).getChannel();
            out = new FileOutputStream(dest).getChannel();

            long size = in.size();
            MappedByteBuffer buf = in.map(FileChannel.MapMode.READ_ONLY, 0, size);

            out.write(buf);

      } finally {
            if (in != null)            in.close();
            if (out != null)      out.close();
      }
}

This will even work if your files are larger than physical memory, but it may swap out a lot of pages you'd have rather kept in memory.

CyTG

gforman++;

shiva_in

MappedByteBuffer keeps the input file open even after proper closing of channel...
Here is the way to solve this..

in = new FileInputStream(source).getChannel();
out = new FileOutputStream(dest).getChannel();
in.transferTo( 0, in.size(), out);

that's it :)

gforman

shiva_in++; shiva_in++;

Let's hear it for the power of collaboration/sharing (e.g. experts-exchange) & may the best ideas bubble to the top.