Java-->多線程複製（文件指針）

--> 這裡用到兩種方法...其實也不算兩種，就一點點不一樣而已...

---> Test 測試類

package com.dragon.java.multithreadcopy;

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

/*
 * 利用多線程複製文件1
 */
public class Test {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner scanner = new Scanner(System.in);
        System.out.println("請輸入文件路徑：");
        File srcFile = new File(scanner.next());
        System.out.println("請輸入線程數：");
        int n = scanner.nextInt();
        if (!srcFile.exists()) {
            System.out.println("該文件不存在！");
        }

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

　　　　　// 從線程數得到每個線程要複製的數據大小
        long partLenghth = srcFile.length() / n + 1;
        for (int i = 1; i < n + 1; i++) {
　　　　　　　// 每次複製的開始和結束位置
            new MyThread(srcFile, desFile, partLenghth * (i - 1), partLenghth
                    * i).start();

        }
    }
}

--> MyThread類即線程實現類

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();
    }

　　 // 構造方法傳入源文件、目標文件、本次開始位置以及結束位置
    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");

　　　　　　　// 將文件指針移動到將要開始複製的位置
            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);
　　　　　　　　　 // 當讀取到的位置大於或等於要結束的位置時跳出迴圈
                if (rafSrc.getFilePointer() >= end) {
                    break;
                }
            }
        } catch (IOException e) {
            System.out.println(e);
        }
    }

}

--> -----------------------------------------------------------------------邪惡的分割線----------------------------------------------------------------------------

--> Test測試

import java.util.Scanner;

/*
 * 利用多線程複製文件利用多線程複製文件2
 */
public class Test {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner scanner = new Scanner(System.in);
        System.out.println("請輸入文件路徑：");
        File srcFile = new File(scanner.next());
        System.out.println("請輸入線程個數：");
        int n = scanner.nextInt();
        if (!srcFile.exists()) {
            System.out.println("該文件不存在！");
        }

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

        long partLenghth = srcFile.length() / n + 1;
        for (int i = 1; i < n + 1; i++) {
　　　　　　　// 每次傳入單線程複製的長度
            new MyThread(srcFile, desFile, partLenghth, MyThread.getPointer())
                    .start();
        }
    }
}

--> MyThread線程實現類

 1 package com.dragon.java.newthreadcopy;
 2 
 3 import java.io.File;
 4 import java.io.IOException;
 5 import java.io.RandomAccessFile;
 6 
 7 public class MyThread extends Thread {
 8     private File srcFile;
 9     private File desFile;
10     private long partLength;
11     private static long pointer = 0;
12 
13     MyThread() {
14         super();
15     }
16 
17     MyThread(File srcFile, File desFile, long partLength, long pointer) {
18         super();
19         this.srcFile = srcFile;
20         this.desFile = desFile;
21         this.partLength = partLength;
22         MyThread.pointer = pointer;
23     }
24 
25     @Override
26     public void run() {
27         RandomAccessFile rafSrc = null;
28         RandomAccessFile rafDes = null;
29         try {
30             rafSrc = new RandomAccessFile(srcFile, "r");
31             rafDes = new RandomAccessFile(desFile, "rw");
32 
33             rafSrc.seek(pointer);
34             rafDes.seek(pointer);
35 
　　　　　　　　　// 一次性複製完整的一部分長度
36             byte[] buffer = new byte[(int) partLength];
37             int len = rafSrc.read(buffer);
38             rafDes.write(buffer, 0, len);
39             pointer = rafSrc.getFilePointer();
40         } catch (IOException e) {
41             System.out.println(e);
42         }
43     }
44 
45     public static long getPointer() {
46         return pointer;
47     }
48 }

--> 感覺第二種也完全是多餘的啊，就是一種方法...