Java-->多线程复制（文件指针）

--> 这里用到两种方法...其实也不算两种，就一点点不一样而已...

---> Test 测试类

package com.dragon.java.multithreadcopy;

import java.io.File;
import java.util.Scanner;

/*
 * 利用多线程复制文件1
 */
public class Test {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入文件路径：");
        File srcFile = new File(scanner.next());
        System.out.println("请输入线程数：");
        int n = scanner.nextInt();
        if (!srcFile.exists()) {
            System.out.println("该文件不存在！");
        }

        File desFile = new File(srcFile.getParent(), "new" + srcFile.getName());

　　　　　// 从线程数得到每个线程要复制的数据大小
        long partLenghth = srcFile.length() / n + 1;
        for (int i = 1; i < n + 1; i++) {
　　　　　　　// 每次复制的开始和结束位置
            new MyThread(srcFile, desFile, partLenghth * (i - 1), partLenghth
                    * i).start();

        }
    }
}

--> MyThread类即线程实现类

package com.dragon.java.multithreadcopy;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

public class MyThread extends Thread {
    private File srcFile;
    private File desFile;
    private long start;
    private long end;

    MyThread() {
        super();
    }

　　 // 构造方法传入源文件、目标文件、本次开始位置以及结束位置
    MyThread(File srcFile, File desFile, long start, long end) {
        super();
        this.srcFile = srcFile;
        this.desFile = desFile;
        this.start = start;
        this.end = end;
    }

    @Override
    public void run() {
        RandomAccessFile rafSrc = null;
        RandomAccessFile rafDes = null;
        try {
            rafSrc = new RandomAccessFile(srcFile, "r");
            rafDes = new RandomAccessFile(desFile, "rw");

　　　　　　　// 将文件指针移动到将要开始复制的位置
            rafSrc.seek(start);
            rafDes.seek(start);

            int len = -1;
            byte[] buffer = new byte[64];
            while ((len = rafSrc.read(buffer)) != -1) {
                rafDes.write(buffer, 0, len);
　　　　　　　　　 // 当读取到的位置大于或等于要结束的位置时跳出循环
                if (rafSrc.getFilePointer() >= end) {
                    break;
                }
            }
        } catch (IOException e) {
            System.out.println(e);
        }
    }

}

--> -----------------------------------------------------------------------邪恶的分割线----------------------------------------------------------------------------

--> Test测试

import java.util.Scanner;

/*
 * 利用多线程复制文件利用多线程复制文件2
 */
public class Test {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入文件路径：");
        File srcFile = new File(scanner.next());
        System.out.println("请输入线程个数：");
        int n = scanner.nextInt();
        if (!srcFile.exists()) {
            System.out.println("该文件不存在！");
        }

        File desFile = new File(srcFile.getParent(), "new" + srcFile.getName());

        long partLenghth = srcFile.length() / n + 1;
        for (int i = 1; i < n + 1; i++) {
　　　　　　　// 每次传入单线程复制的长度
            new MyThread(srcFile, desFile, partLenghth, MyThread.getPointer())
                    .start();
        }
    }
}

--> MyThread线程实现类

package com.dragon.java.newthreadcopy;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

public class MyThread extends Thread {
    private File srcFile;
    private File desFile;
    private long partLength;
    private static long pointer = 0;

    MyThread() {
        super();
    }

    MyThread(File srcFile, File desFile, long partLength, long pointer) {
        super();
        this.srcFile = srcFile;
        this.desFile = desFile;
        this.partLength = partLength;
        MyThread.pointer = pointer;
    }

    @Override
    public void run() {
        RandomAccessFile rafSrc = null;
        RandomAccessFile rafDes = null;
        try {
            rafSrc = new RandomAccessFile(srcFile, "r");
            rafDes = new RandomAccessFile(desFile, "rw");

            rafSrc.seek(pointer);
            rafDes.seek(pointer);

　　　　　　　　　// 一次性复制完整的一部分长度
            byte[] buffer = new byte[(int) partLength];
            int len = rafSrc.read(buffer);
            rafDes.write(buffer, 0, len);
            pointer = rafSrc.getFilePointer();
        } catch (IOException e) {
            System.out.println(e);
        }
    }

    public static long getPointer() {
        return pointer;
    }
}

--> 感觉第二种也完全是多余的啊，就是一种方法...