利用多线程分割文件

主要用到的

RandomAccessFile这个类的

seek（）

read（）

 1 import java.io.File;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;

public class MultiThreading extends Thread {
    private File file;// 要分割的文件；
    private int size;// 每一块的大小
    private int pos; // 位置的大小
    private File file01; //分割的文件

    public MultiThreading(File file, int size, int pos, File file01) {
        super();
        this.file = file;
        this.size = size;
        this.pos = pos;
        this.file01 = file01;
    }

    @Override
    public void run() {
        try {
            segmentation();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public void segmentation() throws IOException {
        RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");
        randomAccessFile.seek((int) pos);  //设置随机读取的位置
        byte[] arr = new byte[size];
        int read = randomAccessFile.read(arr);   //随机读取
        FileOutputStream fileOutputStream = new FileOutputStream(file01);
        fileOutputStream.write(arr, 0, read);
        randomAccessFile.close();
        fileOutputStream.close();
    }
//测试方法如下
    public static void main(String[] args) throws IOException {
        int danwei =  1024*1024*10 ;
        File file2 = new File("F:\系统必备软件.zip");
        long length = file2.length();
        int unit = (int) ((length + danwei - 1) / danwei);
        for (int i = 0; i < unit; i++) {
            File createTempFile = new File("F:\123\" + (100000 + i + 1) + ".tmp");
            MultiThreading multiThreading = new MultiThreading(file2, danwei, i * danwei, createTempFile);
            multiThreading.start();
            String name2 = multiThreading.getName();
            System.out.println("线程"+name2+"开始运行");
        }

    }
}