package com.wxh.random;

import java.io.*;

/**
 * 多线程拷贝文件
 * 
 * @author Administrator
 * 
 */
public class ThreedRandomAccessFileDemo {

  public static void main(String[] args) throws IOException {
    File source = new File("E:\\test\\a.txt");
    File target = new File("E:\\copy");

    copyFileByThread(source, target);

  }

  private static void copyFileByThread(File source, File target)
      throws IOException {
    if (!target.exists()) {
      target.mkdirs();
    }

    File file = new File(target, source.getName());

    if (!file.exists()) {
      file.createNewFile();
    }

    // 循环开启线程
    int threadCount = 3;
    long unitLength = source.length() / threadCount;
    for (int i = 0; i < threadCount; i++) {
      long start = unitLength * i;
      long end = source.length();

      new CopyThread(source, file, start, end).start();
    }
  }

  static class CopyThread extends Thread {
    File source;
    File target;
    long start;
    long end;

    public CopyThread(File source, File target, long start, long end) {
      this.source = source;
      this.target = target;
      this.start = start;
      this.end = end;
    }

    @Override
    public void run() {
      RandomAccessFile reader = null;
      RandomAccessFile writer = null;

      try {
        reader = new RandomAccessFile(source, "rw");
        writer = new RandomAccessFile(target, "rw");
        writer.setLength(source.length());

        
        byte[] buf = new byte[100];
        reader.seek(start);
        writer.seek(start);

        long finished = start;

        while (finished < end) {
          if (finished + buf.length >= end) {
            reader.read(buf, 0, (int) (end - finished));
            writer.write(buf, 0, (int) (end - finished));
          } else {
            reader.read(buf);
            writer.write(buf);
          }
          finished += buf.length;
        }
      } catch (FileNotFoundException e) {
        e.printStackTrace();
      } catch (IOException e) {
        e.printStackTrace();
      } finally {
        try {
          reader.close();
          writer.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getId() + "拷贝完毕");
      }

    }
  }
}