Java 使用IO流实现大文件的分割与合并实例详解

//文件分割的方法（方法内传入要分割的文件路径以及要分割的份数）
private static void splitFileDemo(File src, int m) {
 if(src.isFile()) {
  //获取文件的总长度
  long l = src.length();
  //获取文件名
  String fileName = src.getName().substring(0, src.getName().indexOf("."));
  //获取文件后缀
  String endName = src.getName().substring(src.getName().lastIndexOf("."));
  System.out.println(endName);
  InputStream in = null;
  try {
   in = new FileInputStream(src);
   for(int i = 1; i <= m; i++) {
    StringBuffer sb = new StringBuffer();
    sb.append(src.getParent()).append("\\").append(fileName)
    .append("_data").append(i).append(endName);
    System.out.println(sb.toString());
    File file2 = new File(sb.toString());
    //创建写文件的输出流
    OutputStream out = new FileOutputStream(file2);
    int len = -1;
    byte[] bytes = new byte[10*1024*1024];
    while((len = in.read(bytes))!=-1) {
     out.write(bytes, 0, len);
     if(file2.length() > (l / m)) {
      break;
     }
    }
    out.close();
   }
  } catch (Exception e) {
   e.printStackTrace();
  }
  finally {
   try {
    in.close();
   } catch (IOException e) {
    e.printStackTrace();
   }
  }
 }
}

//文件合并的方法（传入要合并的文件路径）
private static void joinFileDemo(String... src) {
 for(int i = 0; i < src.length; i++) {
  File file = new File(src[i]);
  String fileName = file.getName().substring(0, file.getName().indexOf("_"));
  String endName = file.getName().substring(file.getName().lastIndexOf("."));
  StringBuffer sb = new StringBuffer();
  sb.append(file.getParent()).append("\\").append(fileName)
  .append(endName);
  System.out.println(sb.toString());
  try {
   //读取小文件的输入流
   InputStream in = new FileInputStream(file);
   //写入大文件的输出流
   File file2 = new File(sb.toString());
   OutputStream out = new FileOutputStream(file2,true);
   int len = -1;
   byte[] bytes = new byte[10*1024*1024];
   while((len = in.read(bytes))!=-1) {
    out.write(bytes, 0, len);
   }
   out.close();
   in.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
 }
 System.out.println("文件合并完成！");
}