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网络编程

IP地址

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 四个字节组成 0-255
- ipv6 128位。八个无符号整数！
```
2001:1ab2:cccc:0000:0015:1e2d:1314:22bb
```
- 公网（互联网）私网（局域网）
  - ABCD类地址
  - 192.168..xx.xx 专门给组织内部使用

public class Ip {
    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 localHost = InetAddress.getLocalHost();
            System.out.println(localHost);
            //百度ip地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);

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

端口

端口表示计算机上的一个程序的进程

不同的进程又不同的端口号！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，不同协议端口号可以相同
端口号分类
- 公有端口0-1023
  - HTTP:80
  - HTTPS:443
  - FTP:21
  - Telent:23
- 程序注册端口：1024-49151 分配和用户和程序
  - Tomcat：8080
  - MySQL:3306
  - Oracle：1521
- 动态端口、私有端口：49152-65535
```
netstat -ano #查看所有的端口
netstat -ano|findstr ""  #查看指定的端口
tasklist|findstr ""  #查看指定端口的进程
```

通信协议

1595407114137

协议：约定，就好比我现在说的普通话才能交流

网络通信协议：速率、传输码率、代码结构、传输控制

问题：非常的复杂？

大事化小：分层！

TCP/IP协议簇:实际上时一组协议

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
- A你愁啥？B瞅你咋地？A干一场！最少需要三次才能保证稳定连接
- A我要走了 B你真的要走了么？ B你真的真的要走了么？ A我真的要走了
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，都可以发送
导弹
DDOS：洪水攻击！饱和攻击

TCP实现聊天

客户端

连接服务器 Socket
发送消息

//客户端
public class TcpClientDemo {
    public static void main(String[] args) {
            Socket socket = null;
            OutputStream outputStream = null;
        try {
            //1.知道服务器的地址
            InetAddress serverIp = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建一个socket连接
            socket = new Socket(serverIp,port);
            //3.发送消息 IO流
            outputStream = socket.getOutputStream();
            outputStream.write("nihao".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (outputStream != null)
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(socket != null)
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

服务器

建立服务端口 ServerSocket
等待用户的连接通过accept
接受用户的消息

//服务端
public class TcpServerDemo {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket accept = null;
        InputStream inputStream = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        try {
            //1.有一个地址
            serverSocket = new ServerSocket(9999);
            //2.等待客户端连接进来
            accept = serverSocket.accept();
            //3.读取客户端的消息
            inputStream = accept.getInputStream();
            //管道流
            byteArrayOutputStream = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len;
            while ((len=inputStream.read(buffer)) != -1){
                byteArrayOutputStream.write(buffer,0,len);
            }
            System.out.println(byteArrayOutputStream.toString());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (byteArrayOutputStream != null)
                byteArrayOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(inputStream != null)
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if(accept != null)
                accept.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (serverSocket != null)
                serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
    }
}

TCP文件上传实现

服务器端

public class TCPServer{
    public static void main(String[] args){
        ServerSocket serverSocket = null;
        Socket accept = null;//阻塞式监听，会一直等待客户端连接
        InputStream inputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            //创建服务
            serverSocket = new ServerSocket(9090);
            //监听客户端的连接
            accept = serverSocket.accept();
            //获取输入流
            inputStream = accept.getInputStream();
            //文件输出
            fileOutputStream = new FileOutputStream(new File("基础语法\receive.jpg"));
            byte[] buffer = new byte[1024];
            int len;
            while ((len = inputStream.read(buffer)) != -1){
                fileOutputStream.write(buffer,0,len);
            }
            //通知客户端我接受完毕了
            OutputStream outputStream = accept.getOutputStream();
            outputStream.write("我接受完毕了，可以断开了".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            try {
                if (fileOutputStream != null)
                    fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (inputStream != null)
                    inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (accept != null)
                    accept.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (serverSocket != null)
                    serverSocket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

客户端

public class TcpClient{
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream outputStream = null;
        FileInputStream fileInputStream = null;
        InputStream inputStream = null;
        ByteArrayOutputStream byteArrayOutputStream = null;
        try {
            //建立Socket连接
            socket = new Socket(InetAddress.getByName("127.0.0.1"),9090);
            //创建一个输出流
            outputStream = socket.getOutputStream();
            //文件流
            //读取文件
            fileInputStream = new FileInputStream(new File("基础语法\沙滩.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!
            //确定服务器接受完毕，才能断开连接
            inputStream = socket.getInputStream();
            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());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //关闭资源
            try {
                if (byteArrayOutputStream!=null)
                byteArrayOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (inputStream!=null)
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (fileInputStream!=null)
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (outputStream!=null)
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (socket!=null)
                socket.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }

    }
}

Tomcat

服务端

自定义 S
Tomcat服务器 S java后台开发！

客户端

自定义 C
浏览器 B

UDP

发短信：不用链接需要知道对方的地址

发送消息

发送端

//不需要连接服务器
public class Demo {
    public static void main(String[] args) throws Exception {
        //建立一个Socket
        DatagramSocket datagramSocket = new DatagramSocket();
        //建个包
        String msg = "nihao";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
         int port = 9999;
         //数据  数据的长度起始  发送给谁
        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
        //发送包
        datagramSocket.send(datagramPacket);
    }
}

接收端

等待客户端的连接
public class Demo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket datagramSocket = new DatagramSocket(9999);
        //接收数据  接受包
        byte[] buffer = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);

        //阻塞接收
        datagramSocket.receive(datagramPacket);

        System.out.println(datagramPacket.getAddress().getHostAddress());
        System.out.println(new String(datagramPacket.getData(),0,datagramPacket.getLength()));

        //关闭连接
        datagramSocket.close();
    }

循环发送消息

public class Sender01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        //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();
    }
}

循环接收消息

public class Receicer01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        while (true){
            //准备接受包裹
            byte[] contain= new byte[1024];
            DatagramPacket packet = new DatagramPacket(contain,0,contain.length);
            socket.receive(packet);//阻塞式接受包裹

            //断开连接  bye
            byte[] data = packet.getData();
            String datas = new String(data,0,data.length);
            System.out.println(datas);
            if (datas.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

在线咨询：两个人都可以是发送方，也都可以时接收方多线程实现

发送线程

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();
            }
        }
        socket.close();
    }
}

接收线程

public class TalkReceive implements Runnable {
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;
    public TalkReceive(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 {
                //准备接受包裹
                byte[] contain= new byte[1024];
                DatagramPacket packet = new DatagramPacket(contain,0,contain.length);
                socket.receive(packet);//阻塞式接受包裹
                //断开连接  bye
                byte[] data = packet.getData();
                String datas = new String(data,0,data.length);
                System.out.println(msgFrom+":"+datas);
                if (datas.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

学生端

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 TalkReceive(8888,"老师")).start();
    }
}

老师端

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 TalkReceive(9999,"学生")).start();
    }
}

URL

统一资源定位符:定位互联网上的某一个资源

协议://ip地址:端口/项目名/资源

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

下载网络资源

public class Url {
    public static void main(String[] args) throws Exception {
        //下载地址
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=qiu&password=123");
        //连接到这个资源  HTTP

        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fileOutputStream = new FileOutputStream("基础语法\abc.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();
    }
}

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原文地址：https://www.cnblogs.com/qiudajiang/p/13376882.html

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网络编程

网络编程

IP地址

端口

通信协议

TCP实现聊天

TCP文件上传实现

Tomcat

UDP

在线咨询：两个人都可以是发送方，也都可以时接收方 多线程实现

URL

在线咨询：两个人都可以是发送方，也都可以时接收方多线程实现