FileReadBuffer

package org.andy.example;

import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.Arrays;

/**
 *
 * @author andy
 */
public class FileReadBuffer {

    private static final int CHUNK_SIZE = 1024 * 100;
    private static final String PATH = "/data/VM/Security.vdi";

    public static void main(String[] args) throws IOException {
        readFileDirect();
        readFileIndirect();
        readFileUsual();
    }

    private static void readFileDirect() throws IOException {
        final ByteBuffer buffer = ByteBuffer.allocateDirect(CHUNK_SIZE);
        long time1 = System.currentTimeMillis();
        readFileBuffer(buffer);
        timeElapsed(time1);
    }

    private static void readFileIndirect() throws IOException {
        final ByteBuffer buffer = ByteBuffer.allocate(1024 * 10);
        long time1 = System.currentTimeMillis();
        readFileBuffer(buffer);
        timeElapsed(time1);
    }

    private static void readFileBuffer(ByteBuffer buffer) throws IOException {
        String path = PATH;
        FileChannel fc = FileChannel.open(Paths.get(path), StandardOpenOption.READ);
        int read = fc.read(buffer);
        long total = read;
        while (read >= 0) {
            total += read;
            buffer.clear();
            read = fc.read(buffer);
        }
        System.out.println("Total: " + total);
        fc.close();
    }

    private static void readFileUsual() throws IOException {
        byte[] data = new byte[CHUNK_SIZE];
        long time1 = System.currentTimeMillis();
        try (FileInputStream fs = new FileInputStream(PATH)) {
            int read = fs.read(data, 0, data.length);
            long total = read;
            while (read >= 0) {
                total += read;
                Arrays.fill(data, (byte) 0);
                read = fs.read(data, 0, data.length);
            }
            System.out.println("Total: " + total);
        }
        timeElapsed(time1);
    }

    private static void timeElapsed(long time1) {
        long time2 = System.currentTimeMillis();
        System.out.println("Time:" + (time2 - time1));
    }

}