使用BufferedOutputStream创建大文件需要很长时间

Question

I have a file which is comprised of one serialized String object written to the start of the file followed by the raw bytes of the file I am attempting to extract.

Here is my code:

FileInputStream fileInputStream = new FileInputStream("C:\Test.tst");
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
String string = (String) objectInputStream.readObject();
FileOutputStream fileOutputStream = new FileOutputStream("C:\ExtractedTest.tst");
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
while(fileInputStream.available())
{
  int i = fileInputStream.read();
  bufferedOutputStream.write(i);
}
bufferedOutputStream.close();
fileOutputStream.close();

The code takes an unusable long time for large files (1.5 GB, for example). How can I speed up the code? Am I using the wrong classes?

Regards.

Answer 1

First of all you don't need that I guess:

ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
String string = (String) objectInputStream.readObject();

... and your loop should look more like that:

final byte[] temp = new byte[1000];
while (fileInputStream.available() > 0){
 int i = fileInputStream.read(temp);
 bufferedOutputStream.write(temp, 0, i);
}

Answer 2

You can try to finetune your application by changing the buffer size.

http://docs.oracle.com/javase/7/docs/api/java/io/BufferedOutputStream.html

Here you have documented a version of the constructor with a buffer size. Maybe you can use a big buffer (at expense of your memory usage, of course, be ready to increase your heap size too)

Increase heap size in Java