java学习之IO文件分割

 package om.gh.homework;
 import java.io.*;
 /**
  * 实现分割文件;
  * @param file
  */
 public class HomeWork {
     /**
      * @param src
      *            要分割的文件路径
      * @param n
      *            每个文件的大小以mb为单位
      * @param desc
      *            分割的文件存放路径
      * @throws FileNotFoundException
      */
     public static void filesplit(File src, int mb, File desc)
             throws FileNotFoundException {
         // 判断文件路径
         if (src.exists() && src.isFile() && desc.isDirectory()) {
             int fileSize = mb * 1024 * 1024;
             int n;
             // 判断要分割文件的个数n;
             if (src.length() % fileSize == 0)
                 n = (int) (src.length() / fileSize);
             else
                 n = (int) (src.length() / fileSize) + 1;
             try {
                 InputStream is = new FileInputStream(src);
                 BufferedInputStream bis = new BufferedInputStream(is);
                 for (int i = 0; i < n; i++) {// 循环写入每个文件;
                     byte[] b = new byte[fileSize];
                     String newfile = desc.getPath() + File.separator
                             + src.getName()+"_"+ i + ".dat";
                     BufferedOutputStream bos = new BufferedOutputStream(//缓存流
                             new FileOutputStream(newfile));
                     int len = -1;
                     int count=0;
                     while ((len = bis.read(b)) != -1) {
                         bos.write(b,0,len);
                         count+=len;
                         bos.flush();
                         if(count>=fileSize)break;
                     }
                     bos.close();
                 }
                 bis.close();
                 is.close();
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             } catch (IOException e) {
                 e.printStackTrace();
             }
         } else {
             throw new FileNotFoundException("文件不存在或者参数错误！");
         }
     }

     public static void main(String[] args) {
         File src = new File("F:\\电影\\万万没想到.mp4");//要分割的目标文件
         File desc = new File("f:\\视频\\");//分割完存放的路径
         int mb = 500;// 每个文件大小，以Mb为单位；
         System.out.println("开始分割...");
         try {
             filesplit(src, mb, desc);
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         }
         System.out.println("分割完成！");
     }
 }

 package om.gh.homework;
 import java.io.*;
 /**
  * 把分割后的文件合并
  *
  * @author ganhang
  *
  */
 public class Homework2 {
     /**
      *
      * @param desc
      *            合成后的文件路径
      * @param src
      *            要合成的文件列表
      */
     public static void merge(File desc, File... src) {
         try {
             String filename = src[0].getName().substring(0,
                     src[0].getName().lastIndexOf("_"));
             File newfile = new File(desc.getPath() + File.separator + filename);
             OutputStream os = new FileOutputStream(newfile);
             BufferedOutputStream bos = new BufferedOutputStream(os);
             for (int i = 0; i < src.length; i++) {
                 BufferedInputStream bis = new BufferedInputStream(
                         new FileInputStream(src[i]));
                 byte[] b = new byte[1024 * 1024];
                 int len = -1;
                 while ((len = bis.read(b)) != -1) {
                     bos.write(b, 0, len);
                     bos.flush();
                 }
                 bis.close();
             }
             bos.close();
             os.close();
             System.out.println("合成成功！");
         } catch (FileNotFoundException e) {
             e.printStackTrace();
         } catch (IOException e) {
             e.printStackTrace();
         }
     }
     public static void main(String[] args) {
         File desc=new File("f:\\视频\\");
         File [] src={
                 new File("f:\\视频\\万万没想到.mp4_0.dat"),
                 new File("f:\\视频\\万万没想到.mp4_1.dat"),
                 new File("f:\\视频\\万万没想到.mp4_2.dat"),
                 new File("f:\\视频\\万万没想到.mp4_3.dat")
         };
         System.out.println("开始合成...");
         merge(desc,src);
     }
 }