Compressing and decompressing large size data in java?

问题

I need to compress/decompress different types of files that are contained in a Folder the size of that folder might be more than 10-11 GB. I used following code but this is taking long time to compress the data.

BufferedReader in = new BufferedReader(new FileReader("D:/ziptest/expansion1.MPQ"));
BufferedOutputStream out = new BufferedOutputStream(
    new GZIPOutputStream(new FileOutputStream("test.gz")));

int c;
while ((c = in.read()) != -1)
  out.write(c);
in.close();
out.close();

Please suggest me some fast compressing and decompressing library in java, i also want to split the large file in different parts such as in a chunk of 100MB each.

回答1:

Reader/Writer is only for Text and if you try to read binary with these is will get corrupted.

Instead I suggest you use FileInputStream. The fastest way to copy the data is to use your own buffer.

InputStream in = new FileInputStream("D:/ziptest/expansion1.MPQ");
OutputStream out = new GZIPOutputStream(
            new BufferedOutputStream(new FileOutputStream("test.gz")));

byte[] bytes = new byte[32*1024];
int len;
while((len = in.read(bytes)) > 0)
   out.write(bytes, 0, len);

in.close();
out.close();

Since you reading large chunks of bytes, it is more efficient not to BufferedInput/OuptuStream as this removes one copy. There is a BufferedOutptuStream after the GZIPOutputStream as you cannot control the size of data it produces.

BTW: If you are only reading this with Java, you can use DeflatorOutputStream, its slightly faster and smaller, but only supported by Java AFAIK.

来源：https://stackoverflow.com/questions/6955049/compressing-and-decompressing-large-size-data-in-java