Java IO

程序中所有的数据都是以字节流的方式进行传输的，基于磁盘操作的 I/O 接口：File，基于网络操作的 I/O 接口：Socket

// 字节操作的 I/O 接口：InputStream(读) 和 OutputStream(写)
BufferedInputStream bufferedInputStream = null;
BufferedOutputStream bufferedOutputStream = null;
try {
    // 字节输入流：读数据
    bufferedInputStream = new BufferedInputStream(
            new FileInputStream(
                    new File("C:\Users\lixing\Desktop\通话录音.mp3")));
    // 字节输出流：写数据
    bufferedOutputStream = new BufferedOutputStream(
            new FileOutputStream(
                    new File("C:\Users\lixing\Desktop\通话录音_.mp3")));
    // 复制文件
    byte[] readBytes = new byte[1024]; // 缓冲大小
    int readBytesLen; // 读取字节的长度
    while ((readBytesLen = bufferedInputStream.read(readBytes))!= -1) {
        bufferedOutputStream.write(readBytes, 0, readBytesLen);
    }
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (bufferedOutputStream != null) {
        try {
            bufferedOutputStream.close();
        } catch (IOException e) {
            System.out.println("bufferedOutputStream关闭失败");
        }
    }
    if (bufferedInputStream != null) {
        try {
            bufferedInputStream.close();
        } catch (IOException e) {
            System.out.println("bufferedInputStream关闭失败");
        }
    }
}

// 字符操作的 I/O 接口：Reader(读)和Writer(写) 
BufferedReader bufferedReader = null;
BufferedWriter bufferedWriter = null;
try {
    bufferedReader = new BufferedReader(new FileReader(new File("C:\Users\lixing\Desktop\demo.txt")));
    bufferedWriter = new BufferedWriter(new FileWriter(new File("C:\Users\lixing\Desktop\demo_.txt")));
    String readLine;
    while ( (readLine = bufferedReader.readLine()) != null) {
        bufferedWriter.write(readLine+"rn");
    }
} catch (IOException e) {
    e.printStackTrace();
} finally {
    if (bufferedWriter != null) {
        try {
            bufferedWriter.close();
        } catch (IOException e) {
            System.out.println("bufferedWriter关闭失败");
        }
    }
    if (bufferedReader != null) {
        try {
            bufferedReader.close();
        } catch (IOException e) {
            System.out.println("bufferedReader关闭失败");
        }
    }
}

网络 I/O 描述的是计算机之间完成相互通信一种抽象功能。实质是对 Socket 的读取，大部分情况下我们使用的都是基于 TCP/IP 的流套接字，它是一种稳定的通信协议。
当客户端和服务端成功建立连接后都会拥有一个 Socket 实例，每个 Socket 实例都有一个 InputStream 和 OutputStream，正是通过这两个对象来交换数据的