Java FileChannel与Clojure中的ByteBuffer？

Question

I want to use the following code in Clojure to quickly read a file into memory:

FileInputStream f = new FileInputStream( name );
FileChannel ch = f.getChannel( );
byte[] barray = new byte[SIZE];
ByteBuffer bb = ByteBuffer.wrap( barray );
long checkSum = 0L;
int nRead;

while ((nRead = ch.read(bb)) != -1) {
    for (int i = 0; i < nRead; i++)
        checkSum += barray[i];

    bb.clear( );
}

Code from: FileChannel with array ByteBuffer and byte array access

Calling the Java class constructors and dot-methods is straightforward enough, but will using Clojure's while and for cause a significant performance penalty? Is there anything wrong with just trying to convert Clojure the most direct way?

Answer 1

You'll have to use dotimes instead of for and loop..recur instead of while .

However if you are really after performance, instead of reading, I would memory-map the FileChannel and create a LongBuffer from the ByteBuffer so as to read bytes eight by eight.