Speeding up BufferedInputStream and FileOutputStream

[Mads Nielsen]

Hello

import java.io.*;
import java.security.*;

public class backup_client {
	
	public static void makeBackup(String file) throws IOException
	{
		File fileHandle = new File(file);
		long length = fileHandle.length();
		
		//Instantiating a new input stream
		DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
		//Instantiating a new output stream
		OutputStream output = new FileOutputStream("2" + file);
		//Looping through the content of the file byte by byte
		while(in.available() != 0)
		{
			output.write(in.readByte());
		}
		//Closing the FileOutputStream handle
		output.close();
	}
	
	public static void main(String[] args) throws IOException {
		makeBackup("geoApp.psd");
	}
}

running the above code on a ~3MB file takes on average about 1-2 minutes.

How do i make it faster ?

Kind regards Mads Nielsen

[Maneesh Godbole]

What type of file is it? Text? Binary?
Also, why are you reading one byte at one time?

[Mads Nielsen]

Maneesh Godbole wrote:What type of file is it? Text? Binary?
Also, why are you reading one byte at one time?

I guess its binary, its an Adobe Photoshop PSD file.

I am kinda new to Java, i don't know why i read 1 byte at a time.
I thought that the BufferedInputStream() would put the bytes in a buffer, not reading the file byte by byte.

The makeBackup method (horrible name, suggestions are welcome) is supposed to take all kinds of file formats.

??

Kind regards Mads Nielsen

[Rob Spoor]

Either read byte[] by byte[], or use a BufferedOutputStream.

Also, http://www.coderanch.com/how-to/java/AvailableDoesntDoWhatYouThinkItDoes

[Rob Spoor]

Mads Nielsen wrote:I thought that the BufferedInputStream() would put the bytes in a buffer, not reading the file byte by byte.

True, but you're still writing a byte at a time.

[Stephan van Hulst]

The FileChannel class allows you to copy files at the operating system level. Check out the transferTo and transferFrom methods.

[edit]

Oh, and an even easier solution is to use the Files.copy() method.

[Mads Nielsen]

Rob Spoor wrote:

Mads Nielsen wrote:I thought that the BufferedInputStream() would put the bytes in a buffer, not reading the file byte by byte.

True, but you're still writing a byte at a time.

Great. using the example at: http://www.coderanch.com/how-to/java/AvailableDoesntDoWhatYouThinkItDoes speeded things up dramatically.

Copying a 3,42 MB (3.592.192 bytes) file with the old method took on average 127,68 seconds.
Copyting the same file with the new buffered method takes on average 0,3429 seconds.

import java.io.*;
import java.security.*;

public class backup_client {

	public static void makeBackup(String file) throws IOException
	{
		File fileHandle = new File(file);
		long length = fileHandle.length();
		
		//Instantiating a new input stream
		DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
		//Instantiating a new output stream
		OutputStream output = new FileOutputStream("2" + file);
		
		byte[] buffer = new byte[1024];               
		int bytesRead;                               
		while ((bytesRead = in.read(buffer)) != -1)
		{
			output.write(buffer, 0, bytesRead);      
		}
		
		//Closing the FileOutputStream handle
		output.close();
	}
	
	public static void main(String[] args) throws IOException {
		makeBackup("geoApp.psd");
	}
}

Thank you very much.

[Rob Spoor]

You're welcome.

You can still make a few improvements to your code:
1) get rid of the DataInputStream. You aren't using any of its features at all. Change line 12 to this:

InputStream in = new BufferedInputStream(new FileInputStream(file));

2) close the InputStream as well.
3) do the closing of both in a finally block.

If you have Java 7 it will be even easier than ever:

        File fileHandle = new File(file);   
        long length = fileHandle.length();   

        try (InputStream in = new BufferedInputStream(new FileInputStream(file));
             OutputStream output = new FileOutputStream("2" + file))
        {
            byte[] buffer = new byte[1024];                  
            int bytesRead;                                  
            while ((bytesRead = in.read(buffer)) != -1)   
            {   
                output.write(buffer, 0, bytesRead);         
            } 
        }

This so-called try-with-resources block will automatically close both streams now.

[Jesper de Jong]

There are better and easier ways to copy a file. In my answer to your previous post I posted a link to a page with examples that show how to copy a file.