How to determine the size of an InputStream??

Question

Hello,
I need to get the size of an inputstream. In fact, I am working with java.nio.channels and need to tranfer a file from within a Jar to the FileSystem.
I have created a ReadableByteChannel from the jar resource, and a FileChannel from the FileSystem destination. The problem is that to use the FileChannel .tranferFrom(..) I need the size of the src file. But, ReadableByteChannel has no size() method.
How can I determine the size of this InputStream??
advanced Thanx
here is code:
private void copyResourcesToFileSystem(){
          try{
                    String name = getFileName(); // gets the name
                    ReadableByteChannel srcChannel =
                         Channels.newChannel(this.getClass().getClassLoader().getResourceAsStream(("dtd/"+name)));
                    File newFile = new File(TempDirCreator.getXmlDir(),name);
                    FileChannel dstChannel = new FileOutputStream(newFile).getChannel();
                    dstChannel.transferFrom(srcChannel, 0, srcChannel.size());  // doesn't work -- there is no ReadableBC.size()
                    // lets close the show
                    srcChannel.close();
                    dstChannel.close();
          }catch(IOException x){x.printStackTrace();}
          catch(Exception ex){ex.printStackTrace();}
     }

Answer 1

In general the "size of an InputStream" is a meaningless concept. It's possible to have an InputStream that never terminates. So if you can't get a size from whatever you're reading from, you're out of luck.
I missed where you explained why you need the size. I've never felt the need to know how many bytes would be passing through my code when copying from input to output.