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[网络协议]网络编程学习

网络编程

网络编程

网络编程

1.概述

计算机网络：
计算机网络是指将地理位置不同的具有独立功能的多台计算机及其外部设备，通过通信线路连接起来，在网络操作系统，网络管理软件及网络通信协议的管理和协调下，实现资源共享和信息传递的计算机系统

网络编程的目的：传播交流信息，数据交换，通信

2.网络通信的要素

如何实现网络的通信：
通信双方地址：IP、端口号
规则：网络通信的协议：TCP/IP参考模型
网络模型

3.IP

ip地址：InetAddress

唯一定位一台网络上的计算机
127.0.0.1：本机 localhost
ip地址的分类：ipv4 / ipv6 ；公网（互联网） / 私网（局域网）
ipv4：127.0.0.1，4个字节组成，0-255，42亿个
ipv6：fe80::7080:2207:969c:dd25%3，128位，8个无符号整数
域名：记忆IP问题

//测试IP
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress inetAddress1 = InetAddress.getByName("127.0.0.1");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            InetAddress inetAddress4 = InetAddress.getLocalHost();
            System.out.println(inetAddress4);

            //查询网站ip地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);

            //常用方法
            //System.out.println(inetAddress2.getAddress());
            System.out.println(inetAddress2.getHostAddress());
            System.out.println(inetAddress2.getCanonicalHostName());
            System.out.println(inetAddress2.getHostName());

        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}

4.端口

端口表示计算机上的一个程序的进程：

不同的进程有不同的端口号，用来区分软件
被规定0-65535
TCP，UDP，单个协议下，端口号不能冲突
端口分类：公用端口 0-1023 （HTTP:80；HTTPS:443；FTP:21；Telent:23）；程序注册端口：1024-49151，分配给用户或程序（Tomcat:8080；MySQL:3306；Oracle:1521）；动态端口、私有端口：49152-65535

netstat -ano  #查看所有端口
netstat -ano|findstr "5900" #查看指定的端口
tasklist|findstr "8696" #查看指定窗口的进程

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress);
        System.out.println(socketAddress2);

        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName());
        System.out.println(socketAddress.getPort());
    }
}

5.通信协议

网络传输协议：速率，传输码率，代码结构，传输控制
TCP/IP协议簇：实际上是一种协议（重要）

TCP：用户传输协议
UDP：用户数据报协议
IP：网络互联协议

TCP：打电话

连接，稳定
三次握手、四次挥手
客户端、服务端
传输完成，释放连接，效率低

UDP：发短信

不连接，不稳定
客户端、服务端；没有明确的界限
不管有没有准备好，都可以发给你

6.TCP

1.客户端

连接服务器Socket
发送消息

//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {

        Socket socket = null;
        OutputStream os = null;

        try {
            //要知道服务器的地址
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //创建一个socket连接
            socket = new Socket(serverIP,port);
            //发送消息 IO流
            os = socket.getOutputStream();
            os.write("你好".getBytes());

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (os != null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

2.服务器

建立服务器的端口 Server Socket
等待用户的链接 accept
接收用户的消息

//服务端
public class TcpServerDemo01 {
    public static void main(String[] args) {

        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;

        try {
            //我得有一个地址
            serverSocket = new ServerSocket(9999);
            while (true){
                //等待客户端连接过来
                socket = serverSocket.accept();
                //读取客户端的消息
                is = socket.getInputStream();


                //管道流
                baos = new ByteArrayOutputStream();
                byte[] buffer = new byte[1024];
                int len;
                while ((len = is.read(buffer)) != -1){
                    baos.write(buffer,0,len);
                }
                System.out.println(baos.toString());
            }

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            if (baos != null){
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (is != null){
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (socket != null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (serverSocket != null){
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

3.文件上传

客户端

public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        //创建一个socket链接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //创建一个输出流
        OutputStream os = socket.getOutputStream();

        //读取文件
        FileInputStream fis = new FileInputStream(new File("scc.jpeg"));
        //写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len = fis.read(buffer)) != -1){
            os.write(buffer,0,len);
        }

        //通知服务器我已经结束了
        socket.shutdownOutput();

        //确定服务器接受完毕，才能够断开连接
        InputStream is = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2 = is.read(buffer2)) != -1){
            baos.write(buffer2,0,len2);
        }
        System.out.println(baos.toString());

        //关闭资源
        baos.close();
        is.close();
        fis.close();
        os.close();
        socket.close();

    }
}

服务器

public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //监听客户端的连接
        //阻塞式监听，会一直等待客户端连接
        Socket socket = serverSocket.accept();
        //获取输入流
        InputStream is = socket.getInputStream();
        //文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.jpeg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer)) != -1){
            fos.write(buffer,0,len);
        }

        //通知客户端接受完毕了
        OutputStream os = socket.getOutputStream();
        os.write("我接受完毕了，你可以断开了".getBytes());

        //关闭资源
        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();

    }
}

7.TomCat

服务端：自定义 S – TomCat S
客户端：自定义 C – 浏览器 B

8.UDP

1.发送消息

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //建立一个Socket
        DatagramSocket socket = new DatagramSocket();

        //建个包
        String msg = "你好啊，服务器！";

        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;

        //数据，数据长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
        //发送包
        socket.send(packet);

        //关闭流
        socket.close();
    }
}

2.接收消息

//还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接受数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);

        //阻塞接收
        socket.receive(packet);
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        //关闭连接
        socket.close();

    }
}

3.循环发送消息

public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception {

        DatagramSocket socket = new DatagramSocket(8080);

        //准备数据，控制台读取 System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true){
            String data = reader.readLine();
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));

            socket.send(packet);
            if (data.equals("bye")){
                break;
            }
        }

        socket.close();

    }
}

4.循环接收消息

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {

        DatagramSocket socket = new DatagramSocket(6666);

        while (true){
            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet);

            //断开连接
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, packet.getLength());
            System.out.println(receiveData);

            if (receiveData.equals("bye")){
                break;
            }

        }
    }
}

5.多线程在线咨询

public class TalkRecieve implements Runnable{

    DatagramSocket socket = null;
    private int port;
    private String msgFrom;

    public TalkRecieve(int port,String msgFrom) {
        this.port = port;
        this.msgFrom =msgFrom;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true){
            try {
                //准备接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container,0,container.length);
                socket.receive(packet);

                //断开连接
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, packet.getLength());
                System.out.println(msgFrom + ":" + receiveData);

                if (receiveData.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
}

public class TalkSend implements Runnable {

    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;

        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }


    }

    @Override
    public void run() {

        while (true) {
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));
                socket.send(packet);
                if (data.equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkRecieve(8888,"老师")).start();
    }
}

public class TalkTeacher {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkRecieve(9999,"学生")).start();
    }
}

9.URL

统一资源定位符：定位资源的，定位互联网上的某一个资源
DNS域名解析：www.xxx.com ----- xxxx.x.x.x

协议://ip地址:端口/项目名

public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=shengcancheng&password=123");
        System.out.println(url.getProtocol());//协议
        System.out.println(url.getHost());//主机ip
        System.out.println(url.getPort());//端口
        System.out.println(url.getPath());//文件地址
        System.out.println(url.getFile());//全路径
        System.out.println(url.getQuery());//参数
    }
}