Java 分解大文件及合并文件

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
//分解文件
public class DatagramPacket1 {
    public static void main(String[] args) throws IOException {
        FileInputStream fis = new FileInputStream("C:\Users\86176\Desktop\s.jpg");//读一个文件
        byte[] buf = new byte[1024 *10];//一次读10kb
        int len;
        int index1 = 0;
        FileOutputStream fos = new FileOutputStream("C:\Users\86176\Desktop\wx\sk0"+ ++index1);//输出一个文件
        int index2 = -1;
        while ((len = fis.read(buf)) > 0){
            ++index2;
            if (index2 % 5 == 0 && index2 != 0){
                fos.flush();
                fos.close();
                fos = new FileOutputStream("C:\Users\86176\Desktop\wx\sk0"+ ++index1);
            }
            fos.write(buf,0,len);
        }
        fos.flush();
        fos.close();
    }
}

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
//合并文件
public class DatagramPacket2 {
    public static void main(String[] args) throws IOException {
        FileOutputStream fos = new FileOutputStream("C:/Users/86176/Desktop/wx/h.jpg");
        for (int i = 1 ; i <= 3; i++){
            FileInputStream fis = new FileInputStream("C:/Users/86176/Desktop/wx/sk0" + i);
            fos.write(fis.readAllBytes());
        }
        fos.close();
    }
}