java IO流核心代码

FileInputStream f = new FileInputStream("xxx.txt"); //用已存在的文件，创建输入流，用于读出来

    FileOutputStream fileOutputStream = new FileOutputStream("hahaha.txt");//创建输出流，用于写入

    //读

      int a;

      while ((a = f.read())!=-1) {

      //写

fileOutputStream.write(a);

  }

      //关闭

      f.close();

      fileOutputStream.close();

改进读与写：

FileInputStream f = new FileInputStream("xxx.txt"); //用已存在的文件，创建输入流，用于读出来

    FileOutputStream fileOutputStream = new FileOutputStream("hahaha.txt");//创建输出流，用于写入

    //读

    byte []arr = new byte[1024 * 8];

      int a;

      while ((a = f.read())!=-1) {

      //写

fileOutputStream.write(arr, 0,a);;

  }

      //关闭

      f.close();

      fileOutputStream.close();

或者

FileInputStream f = new FileInputStream("xxx.txt"); //用已存在的文件，创建输入流，用于读出来

      FileOutputStream fileOutputStream = new FileOutputStream("hahaha.txt");//创建输出流，用于写入

      BufferedInputStream bufferedInputStream = new BufferedInputStream(f);

      BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream);

      int c;

      while ( (c = bufferedInputStream.read()) != -1) {

bufferedOutputStream.write(c);

}

      bufferedInputStream.close();

      bufferedOutputStream.close();

关于字符操作

FileReader //读字符

FileWrite //写字符