Reading large files -- use FileChannel or BufferedReader?

Question

Question --
I need to read files and get their content. The issue is that I have no idea how big the files will be. My best guess is that most are less than 5kb but some with be huge.
I have it set up using a BufferedReader, which is working fine. It's not the fastest thing (using readLine() and StringBuffer.append()), but so far it's usable. However, I'm worried that if I need to deal with large files, such as a PDF or other binary, BufferedReader won't be so efficient if I do it line by line. (And will I run into issues trying to put a binary file into a String?)
I found a post that recommended FileChannel and ByteBuffer, but I'm running into a java.lang.UnsupportedOperationException when trying to get the byte[] from ByteBuffer.
File f = new File(binFileName);
FileInputStream fis = new FileInputStream(f);
FileChannel fc = fis.getChannel();
// Get the file's size and then map it into memory
int sz = (int)fc.size();
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, sz);
fc.close();
String contents = new String(bb.array()); //code blows up
Thanks in advance.

Answer 1

If all you are doing is reading data I don't think you're going to get much faster than InfoFetcher
you are welcome to use and modify this class, but please don't change the package or take credit for it as your own work
InfoFetcher.java
==============
package tjacobs.io;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Iterator;
* InfoFetcher is a generic way to read data from an input stream (file, socket, etc)
* InfoFetcher can be set up with a thread so that it reads from an input stream
* and report to registered listeners as it gets
* more information. This vastly simplifies the process of always re-writing
* the same code for reading from an input stream.
* <p>
* I use this all over
     public class InfoFetcher implements Runnable {
          public byte[] buf;
          public InputStream in;
          public int waitTime;
          private ArrayList mListeners;
          public int got = 0;
          protected boolean mClearBufferFlag = false;
          public InfoFetcher(InputStream in, byte[] buf, int waitTime) {
               this.buf = buf;
               this.in = in;
               this.waitTime = waitTime;
          public void addInputStreamListener(InputStreamListener fll) {
               if (mListeners == null) {
                    mListeners = new ArrayList(2);
               if (!mListeners.contains(fll)) {
                    mListeners.add(fll);
          public void removeInputStreamListener(InputStreamListener fll) {
               if (mListeners == null) {
                    return;
               mListeners.remove(fll);
          public byte[] readCompletely() {
               run();
               return buf;
          public int got() {
               return got;
          public void run() {
               if (waitTime > 0) {
                    TimeOut to = new TimeOut(waitTime);
                    Thread t = new Thread(to);
                    t.start();
               int b;
               try {
                    while ((b = in.read()) != -1) {
                         if (got + 1 > buf.length) {
                              buf = IOUtils.expandBuf(buf);
                         int start = got;
                         buf[got++] = (byte) b;
                         int available = in.available();
                         //System.out.println("got = " + got + " available = " + available + " buf.length = " + buf.length);
                         if (got + available > buf.length) {
                              buf = IOUtils.expandBuf(buf, Math.max(got + available, buf.length * 2));
                         got += in.read(buf, got, available);
                         signalListeners(false, start);
                         if (mClearBufferFlag) {
                              mClearBufferFlag = false;
                              got = 0;
               } catch (IOException iox) {
                    throw new PartialReadException(got, buf.length);
               } finally {
                    buf = IOUtils.trimBuf(buf, got);
                    signalListeners(true);
          private void setClearBufferFlag(boolean status) {
               mClearBufferFlag = status;
          public void clearBuffer() {
               setClearBufferFlag(true);
          private void signalListeners(boolean over) {
               signalListeners (over, 0);
          private void signalListeners(boolean over, int start) {
               if (mListeners != null) {
                    Iterator i = mListeners.iterator();
                    InputStreamEvent ev = new InputStreamEvent(got, buf, start);
                    //System.out.println("got: " + got + " buf = " + new String(buf, 0, 20));
                    while (i.hasNext()) {
                         InputStreamListener fll = (InputStreamListener) i.next();
                         if (over) {
                              fll.gotAll(ev);
                         } else {
                              fll.gotMore(ev);
     }