06-网络编程

java学习笔记

java学习笔记

发布日期: 2021-10-12

网络编程

1.概述

计算机网络：

计算机网络将地理位置不同、功能独立的多个计算机系统互联起来，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，网络软件/708424)实现网络中资源共享和信息传递的系统。

网络编程的目的：

传播交流信息，数据交换，通信。

想要达到这个效果需要什么：

如何准确定位网络上的一台主机，IP地址，定位计算机上的某个资源
如何传输数据？

javaweb：网页编程 B/S

网络编程：TCP/IP C/S

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：网络通信协议

TCP/IP

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
  - ipv4：127.0.0.1,4个字节组成。
  - ipv6：aaaa : aaaa :aaaa :aaaa :aaaa :aaaa :aaaa :aaaa，128位。8个无符号整数
- 公网(互联网)-私网(局域网)
域名：记忆IP问题！

//测试IP
public class TestIntetAddress {
    public static void main(String[] args) {
        try {

            //查询本机地址
            InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
            InetAddress inetAddress2 = InetAddress.getByName("localhost");
            System.out.println(inetAddress);
            System.out.println(inetAddress2);

            //查询网站IP地址
            InetAddress inetAddress1 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress1);

            //常用方法
            System.out.println(inetAddress2.getCanonicalHostName());//规范的名字
            System.out.println(inetAddress2.getHostAddress());//ip
            System.out.println(inetAddress2.getHostName());//域名，或自己电脑名字


        } 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：65535*2 tcp：80，udp：80，单个协议下端口号不能冲突
端口分类
- 公有端口0~1023
  - HTTP: 80
  - HTTPS: 443
  - FTP: 21
  - Telent: 23
- 程序注册端口：1024~49151，分配用户或者程序
  - Tomcat ： 8080
  - MySQL：3306
  - Oracle：1521
- 动态、私有：49152~65535
```
netstat -ano #查看所有端口
netstat -ano|findstr "  " #查看指定端口
tasklist|findstr "  " #查看指定端口的进程
```

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress inetSocketAddress = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress inetSocketAddress1 = new InetSocketAddress("localhost", 8080);
        System.out.println(inetSocketAddress);
        System.out.println(inetSocketAddress1);

        System.out.println(inetSocketAddress.getAddress());
        System.out.println(inetSocketAddress.getHostName());//地址
        System.out.println(inetSocketAddress.getPort());//端口


    }
}

5.通信协议

协议：约定

网络通信协议:速率，传输码率，代码结构，传输控制

问题；非常复杂

大化小：分层

TCP/IP协议簇:实际上是一组协议

重要：

TCP：用户传输协议
UDP：用户数据报协议

出名的协议：

TCP：
IP：网络互联协议

TCP UDP对比

TCP:打电话

连接，稳定

三次握手，四次挥手
三次握手:最少需要三次，保证稳定连接

A:连接？
B:回答
A:连接
    
A：要断开！    
B：询问？
B：询问？
A：断开！

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

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 outputStream = null;


        try {
            //要知道服务器的地址
            InetAddress byName = InetAddress.getByName("127.0.0.1");
            //端口号
            int port = 9999;
            //创建一个socket连接
            socket = new Socket(byName,port);
            //发送消息 io流
            outputStream = socket.getOutputStream();
            outputStream.write("欢迎".getBytes());

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

        }

服务器

建立服务的端口ServerSocket
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 inputStream = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        try {
            //要有一个地址
            serverSocket = new ServerSocket(9999);
            //等待客户端连接
            socket = serverSocket.accept();
            //读取客户端的消息
            inputStream = socket.getInputStream();
            //管道流
            byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] bytes = new byte[1024];
            int len;
            while ((len = inputStream.read(bytes)) != -1 ){
                byteArrayOutputStream.write(bytes,0,len);
            }
            System.out.println(byteArrayOutputStream.toString());


        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭资源
            if (byteArrayOutputStream != null){
                try {
                    byteArrayOutputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (inputStream != null){
                try {
                    inputStream.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();
                }
            }


        }

    }
}

文件上传

服务器

public class TcpServerDemo02 {
    public static void main(String[] args) throws IOException {
        //创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //监听客户端连接
        Socket socket = serverSocket.accept();//阻塞式监听
        //获取输入流
        InputStream inputStream = socket.getInputStream();
        //文件输出
        FileOutputStream outputStream = new FileOutputStream(new File("图片.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1){
            outputStream.write(buffer,0,len);
        }



        //通知客户端接收完毕
        OutputStream outputStream1 = socket.getOutputStream();
        outputStream1.write("接收完毕".getBytes());





        //关闭资源
        outputStream1.close();
        outputStream.close();
        inputStream.close();
        socket.close();
        serverSocket.close();



    }
}

客户端

public class TcpClientDemo02 {
    public static void main(String[] args) throws IOException {
        //1.创建一个Socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9000);
        //创建输出流
        OutputStream outputStream = socket.getOutputStream();
        //读取文件
        FileInputStream fileInputStream = new FileInputStream(new File("基础语法/src/com/liang/Internet/demo02/5.jpg"));
        //写出文件
        byte[] buffer = new byte[1024];
        int len;
        while ((len = fileInputStream.read(buffer)) != -1){
            outputStream.write(buffer,0,len);
        }
        //通知服务器，我已经结束了
        socket.shutdownOutput();//我已经传输完了
        //确定服务器接收完毕，才能断开连接
        InputStream inputStream = socket.getInputStream();
        //String byte[]
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2 = inputStream.read(buffer2)) != -1){
            byteArrayOutputStream.write(buffer2,0,len2);
        }
        System.out.println(byteArrayOutputStream.toString());


        //关闭资源
        byteArrayOutputStream.close();
        inputStream.close();
        fileInputStream.close();
        outputStream.close();
        socket.close();




    }
}

Tomcat

服务端

自定义 S
Tomcat服务器 S

客户端

自定义 C
浏览器 B

7.UDP

发短信：不用连接，但需要知道地址

发送消息

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws IOException {
        //建议一个Socket
        DatagramSocket datagramSocket = new DatagramSocket();
        //建个包
        String msg = "服务器";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port =9090;

        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,9090);


        //发送包
        datagramSocket.send(datagramPacket);
        //关闭流
        datagramSocket.close();

    }
}

接收消息

//还是要等待客户端连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws IOException {
        //开放端口
        DatagramSocket datagramSocket = new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);//接收
        datagramSocket.receive(datagramPacket);//阻塞接受
        System.out.println(datagramPacket.getAddress().getHostName());
        System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));
        //关闭连接
        datagramSocket.close();

    }
}

循环发送消息

public class UdpSenderDemo01 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(8888);





        while (true){
            //准备数组：控制台读取System.in
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            String s = reader.readLine();

            byte[] bytes = s.getBytes();
            DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost",6666));
            socket.send(packet);
            if (s.equals("bye")){
                break;
            }
        }

        socket.close();
    }
}

循环接收消息

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(6666);

        while (true){
            //准备接收包裹
            byte[] bytes = new byte[1024];
            DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length);
            socket.receive(packet);//阻塞式接收包裹
            //断开连接 bye
            String s = new String(packet.getData(), 0, packet.getLength());
            System.out.println(s);
            if (s.equals("bye")){
                break;
            }
        }

        socket.close();


    }

}

发送消息,即可以为发送方，也可以为接收方

public class UdpSenderDemo02 implements Runnable{
        private DatagramSocket socket;
        private int Fromport;
        private int toPort;
        private String toIP;
        BufferedReader reader;


    public UdpSenderDemo02(int fromport, int toPort, String toIP){
        Fromport = fromport;
        this.toPort = toPort;
        this.toIP = toIP;

        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 s = reader.readLine();
                byte[] bytes = s.getBytes();
                DatagramPacket packet = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress(toIP, toPort));
                socket.send(packet);
                if (s.equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

            socket.close();
        }
    }


}

public class UdpReceiveDemo02 implements Runnable{
        DatagramSocket socket ;
        private int fromPort;
        private String msg;

    public UdpReceiveDemo02( int fromPort,String msg){
        this.fromPort = fromPort;
        this.msg = msg;
        try {
            socket= new DatagramSocket(fromPort);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }





    @Override
    public void run() {
        while (true){
            try {
                //准备接收包裹
                byte[] bytes = new byte[1024];
                DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length);
                socket.receive(packet);//阻塞式接收包裹
                //断开连接 bye
                String s = new String(packet.getData(), 0, packet.getLength());
                System.out.println( msg +" : " + s);
                if (s.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

public class TalkA {
    public static void main(String[] args){
        new Thread(new UdpSenderDemo02(6584,6666,"localhost")).start();
        new Thread(new UdpReceiveDemo02(9090,"B")).start();
    }
}





public class TalkB {
    public static void main(String[] args) {
        new Thread(new UdpSenderDemo02(9999,9090,"localhost")).start();
        new Thread(new UdpReceiveDemo02(6666,"A")).start();
    }
}

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：将域名变成ip地址

协议：//IP地址:端口/项目名/资源

public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=lwj&&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
        System.out.println(url.getFile());//文件全路径
        System.out.println(url.getQuery());//参数
    }

}

public class URLDown {
    public static void main(String[] args) throws IOException {
        //下载地址
        URL url = new URL("http://localhost:8080/lwj/Text.txt");
        //连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fileOutputStream = new FileOutputStream("text.txt");

        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer)) != -1){
            fileOutputStream.write(buffer,0,len);
        }
        fileOutputStream.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接
    }

半页

https://eternallyevery.github.io/2021/10/12/06-wang-luo-bian-cheng/

本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源半页 !

java学习笔记

评论

上一篇

07-多线程

多线程

2021-10-12 java学习笔记

java学习笔记

下一篇

05-GUI编程

GUI编程

2021-10-12 java学习笔记

java学习笔记