计算机网络

127.0.0.1

IP :互联网协议地址 ipv4和ipv6  设备在网络中的唯一表示

 

DNS把域名解析为了IP

IPv4 4字节 点分十进制

IPv6  16字节  八组  冒分十六进制  去头0，0位压缩

端口号： 找到设备中软件的标识    两个字节表示的整数  0~65535

协议    :计算机网络中，连接和通信的规则被称为计算机网络通信

InetAddress 类使用

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//通过主机名获取主机对象       InetAddress inetAddress= InetAddress.getByName("DESKTOP-4MKNLPK");       System.out.println("主机名为"+inetAddress.getHostName());       System.out.println("IP为"+inetAddress.getHostAddress());

　　

 

1 允许部分数据丢失，使用UDP（用户数据报）协议    无连接 

发送数据 （单播）

 

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class Client {     public static void main(String[] args) throws IOException {           Scanner scanner =new Scanner(System.in);         //找码头   数据报 套接字         DatagramSocket datagramSocket=new DatagramSocket();         //数据报 封装         String string=scanner.next();         byte[] bytes=string.getBytes();         InetAddress inetAddress=InetAddress.getByName("127.0.0.1");         int port=10086;         DatagramPacket datagramPacket=new DatagramPacket(bytes,bytes.length,inetAddress,port);         //发送数据         datagramSocket.send(datagramPacket);         System.out.println("发送成功");         //释放资源         datagramSocket.close();     } }

接收数据

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public class Server {     public static void main(String[] args) throws IOException {         //找码头   数据报套接字         DatagramSocket datagramSocket=new DatagramSocket(10086);         //装数据报箱子         byte[] bytes=new byte[1204];         DatagramPacket datagramPacket=new DatagramPacket(bytes,bytes.length);         //接受数据         System.out.println("接受数据");         datagramSocket.receive(datagramPacket);         System.out.println("接收成功");         //获取箱子中的数据         String string=new String(datagramPacket.getData());         System.out.println(string);         //释放资源         datagramSocket.close();     } }

 

UDP（组播）

MulticastSocket ms=new MulticastSocket（port）//接收端

//把当前计算机绑定一个人组播地址

//组播地址 224.0.0.1~239.255.255.255  组播的预留地址为 224.0.0.1~224.0.0.255

发送数据

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class Client {     public static void main(String[] args) throws IOException {         //套接字         Scanner scanner =new Scanner(System.in);         DatagramSocket datagramSocket=new DatagramSocket();         //装 数据报的箱子         String string=scanner.next();         byte[] bytes=string.getBytes();         InetAddress inetAddress=InetAddress.getByName("224.0.0.15");         int port=14752;         DatagramPacket datagramPacket=new DatagramPacket(bytes,bytes.length,inetAddress,port);         //发送数据         datagramSocket.send(datagramPacket);         System.out.println("发送成功");         //释放资源         datagramSocket.close();     } }

接收数据

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public class Server {     public static void main(String[] args) throws IOException {         //创建 广播套接字对象         MulticastSocket multicastSocket=new MulticastSocket(14752);         //创建数据报报对象         byte[] arr=new byte[1024];         DatagramPacket datagramPacket=new DatagramPacket(arr,arr.length);         //加入组播组         multicastSocket.joinGroup(InetAddress.getByName("224.0.0.15"));         multicastSocket.receive(datagramPacket);         String s=new String(datagramPacket.getData());         System.out.println(s);         //释放资源         multicastSocket.close();     } }

　　

UDP （广播）

广播 InetAddressdd255.255.255.255

 

 2 不允许任何数据丢失，是同TCP（传输控制协议）协议    面向连接

发送端

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/* //套接字  两台机器间通信的端点 Scoket sk=new Socket(host，port); //获取IO流开始写写数据 OutputStream os=socket.getOutputStream(); //将字节输出流转换为字符输出流 OutputStreamWriter osw=new OutputStreamWriter(os); BufferedWriter bw=new BufferedWriter(osw);  */ public class SocketClient {     public static void main(String[] args) throws IOException {         //创建套接字对象         Socket socket=new Socket("192.168.11.61",10000);         //创建字节输出流对象         OutputStream outputStream=socket.getOutputStream();         //字节输出流转换为字符输出流         OutputStreamWriter outputStreamWriter=new OutputStreamWriter(outputStream);         BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);         bufferedWriter.write("带骨头的狗");         bufferedWriter.newLine();         bufferedWriter.close();         //释放资源         socket.close();       } }

接收数据

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//客户端连接服务器三次握手 //在最后一步断开链接，通过四次挥手协议保证连接终止 public class Server {     public static void main(String[] args) throws IOException {         //创建服务器端的套接字对象         ServerSocket socket=new ServerSocket(10000);         //监听客户端连接 阻塞方法         Socket accept=socket.accept();         //创建字节输入流对象，接受         InputStream inputStream=accept.getInputStream();         //字节输入流转换成字符输入流         InputStreamReader inputStreamReader=new InputStreamReader(inputStream);         BufferedReader bufferedReader=new BufferedReader(inputStreamReader);           //readLine阻塞方法，传输的数据报中没有结束符标记         System.out.println(bufferedReader.readLine());         //在关IO流的时候，多了一个往服务器理写结束标记的动作         bufferedReader.close();         socket.close();     } }

　　三次握手 粗浅理解，不是计算机网络

 

   四次挥手  粗浅理解

　　

 

 

 

数据交互小练习

客户端

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public class Client01 {     public static void main(String[] args) throws IOException {         //创建套接字对象         Socket socket=new Socket("127.0.0.1",10086);         //创建字节输出流输出到套接字对象中         OutputStream outputStream=socket.getOutputStream();         //将字节输出流转换为字符输出流         OutputStreamWriter outputStreamWriter=new OutputStreamWriter(outputStream);         BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);         bufferedWriter.write("大白鹅");         bufferedWriter.newLine();         bufferedWriter.flush();         socket.shutdownOutput();         //接受服务器的回复         InputStream inputStream=socket.getInputStream();         //字节输入流转换为字符数入流         InputStreamReader inputStreamReader=new InputStreamReader(inputStream);         BufferedReader bufferedReader=new BufferedReader(inputStreamReader);         System.out.println(bufferedReader.readLine());             bufferedWriter.close();         bufferedReader.close();         socket.close();       } }

　　服务器端

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public class Server {     public static void main(String[] args) throws IOException {         //创建服务器端 套接字对象       ServerSocket serverSocket=new ServerSocket(10086);       // 创建连接 阻塞任务       Socket accept=serverSocket.accept();       //创建字节输入流         InputStream inputStream=accept.getInputStream();         //字节输入流转换为字符数入流         InputStreamReader inputStreamReader=new InputStreamReader(inputStream);         BufferedReader bufferedReader=new BufferedReader(inputStreamReader);         System.out.println(bufferedReader.readLine());             //回复客户端         OutputStream outputStream=accept.getOutputStream();         //将字节输出流转换为字符输出流         OutputStreamWriter outputStreamWriter=new OutputStreamWriter(outputStream);         BufferedWriter bufferedWriter=new BufferedWriter(outputStreamWriter);         bufferedWriter.write("难道你就是传说中的大白鹅");         bufferedWriter.close();         bufferedReader.close();           accept.close();       } }

文件里的数据交互小练习

　　优化 服务端

            文件名随机且唯一(有很小小小的几率重复) UUID

　　　　　　reandomUUID（）

　　　　　　　toString（）.replace()

　　　改为多线程

　　　加线程池

 

类 InetAddress   

ipconfig 查看本机IP地址

私有构造  成员方法

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public class MyInetAddress {     public static void main(String[] args) throws UnknownHostException {         //通过ip获取主机对象         InetAddress inetAddress= InetAddress.getByName("192.168.56.1");         System.out.println("主机名为"+inetAddress.getHostName());         System.out.println("IP为"+inetAddress.getHostAddress());         /*byte[] arr="192.168.56.1".getBytes();         InetAddress inetAddress=InetAddress.getByAddress(arr);         System.out.println(inetAddress.getHostName());*/       } }