计算机网络

IP

ip地址：InetAddress 使用ipconfig查看IP地址

​ 唯一定位一台网络上的计算机

​ 192.168.0.6：本机的ip

​ ip地址分类

​ ipv4 / ipv6

​ IPV4：192.168.0.6，四个字节组成。0~255，可生成42亿；30亿在北美，只有4亿在亚洲。在2011年就用尽

​ IPV6：128位。8个无符号整数

​ 公网（互联网）-私网（局域网）

​ ABCD类地址

​ A类IP地址范围1.0.0.1-126.255.255.254

​ B类IP地址范围128.1.0.1-191.254.255.254

​ C类IP地址范围192.0.1.1-223.255.254.254

​ D类IP地址范围224.0.0.1-239.255.255.254

​ 192.168.xx.xx专门给组织内部使用

​ 域名：记忆问题

package com;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class TestInetAddress {
    //测试IP
    public static void main(String[] args) {
        try {
            //主机地址
            InetAddress inetAddress1 = InetAddress.getByName("192.168.0.6");
            System.out.println(inetAddress1);
            InetAddress inetAddress3 = InetAddress.getByName("localhost");
            System.out.println(inetAddress3);
            //查询网站地址
            InetAddress inetAddress2 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress2);
            //常用的方法
            System.out.println(inetAddress2.getAddress());
            System.out.println(inetAddress2.getCanonicalHostName());//规范的名字
            System.out.println(inetAddress2.getHostAddress());//ip
            System.out.println(inetAddress2.getHostName());//域名，或自己电脑的名字
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }
}

端口

端口表示计算机上的一个程序的进程；

不同的进程有不同的端口号。用来区分软件

被规定0~65535

单个协议下，端口号不能冲突

端口号分类

​ 公有端口号0~1023

​ HTTP：80

​ HTTPS：443

​ FTP：21

​ TELENT：23

​ 程序注册端口号：1024~49151，分配给用户或程序的

​ Tomcat：8080

​ MySQL：3306

​ Oracle：1521

​ 动态，私有：49152~65535一般情况下我们不用

netstat -ano #查看所有的端口
netstat -ano|findstr "5900"#查看指定端口
tasklist|findstr "8696"#查看指定端口的进程

package com.meng.lessonip01;

import java.net.InetSocketAddress;

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress1 = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress socketAddress2 = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress1);
        System.out.println(socketAddress2);

        System.out.println(socketAddress1.getAddress());
        System.out.println(socketAddress1.getHostName());//地址
        System.out.println(socketAddress1.getPort());//端口号


    }
}

通信协议

协议：约定，双方进行交流的规定

网络通信协议：速率，传输码率，代码结构，传输控制。。。。

问题：非常的复杂

大事化小：分层

TCP/IP协议：实际是一种协议

重要：两者都是在传输层

​ TCP：用户传输协议

​ UDP：用户数据报协议

TCP UDP对比

TCP：打电话

​ 连接稳定

​ 三次握手（完成链接） 四次挥手（断开连接）

​ 客户端 服务端

​ 传输完成，释放连接，低效率

UDP：发短信

​ 不连接不稳定

​ 客户端服务端：没有明显的界限

​ 不管有没有准备好都发给你

TCP

客户端

1.连接服务器Socket

2.发送消息

package com.meng.lesson02;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
//客户端
public class TcpClientDemo01 {
    public static void main(String[] args) {
        Socket socket =null;
        OutputStream os =null;
        //1.要知道服务器的地址
        try {
            InetAddress serverIP = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2.创建一个socket链接
            socket = new Socket(serverIP,port);
            //3.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();
            }
            }
        }
    }
}

服务器

1.建立服务器的端口ServerSocket

2.等待用户的连接accept

3.接受用户的消息

package com.meng.lesson02;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;


//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 {
            //1.我得有一个地址
            serverSocket = new ServerSocket(9999);
            //2.等待客户链接
            socket = serverSocket.accept();
            //3.读取客户端消息
            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();
                }
            }
        }
    }
}

文件上传

服务器端

package com.meng.lesson02;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class TcpServerDemo02 {
    public static void main(String[] args) throws Exception {
        //1.创建服务
        ServerSocket serverSocket = new ServerSocket(9000);
        //2.监听客户端的链接
        Socket socket = serverSocket.accept();//阻塞式监听，会一直等待客户端连接
        //3.获取输入流
        InputStream is = socket.getInputStream();
        //4.文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.jpg"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        //通知客户端我接收完了
        OutputStream os = socket.getOutputStream();
        os.write("我接收完了，你可以关闭了".getBytes());
        //关闭资源
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

客户端

package com.meng.lesson02;

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;

public class TcpClientDemo02 {
    public static void main(String[] args) throws Exception {
        //1.创建一个Socket链接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9000);
        //2.创建一个输出流
        OutputStream os = socket.getOutputStream();
        //3.读取文件
        FileInputStream fis = new FileInputStream(new File("mjlh.jpg"));
        //4.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();//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();
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len2=inputStream.read(buffer2))!=-1){
            bos.write(buffer2,0,len2);
        }
        System.out.println(bos.toString());
        //5.关闭资源
        bos.close();
        inputStream.close();
        fis.close();
        os.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

UDP

发短信：不用链接，需要知道对方地址

发送消息

发送端

package com.meng.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一个Socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String msg = "你好服务器";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port=9090;
        //数据，数据的长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

        //3.发送包
        socket.send(packet);
        //4.关闭流
        socket.close();
    }
}

接收端

package com.meng.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(packet);//阻塞接受
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0, packet.getLength()));
        //关闭连接
        socket.close();
    }
}

咨询

循环发送消息

package com.meng.chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class UdpSenderDemo01 {
    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, data.length(), new InetSocketAddress("localhost", 6666));
            socket.send(packet);
            if (data.equals("bye")){
                break;
            }
        }

        socket.close();
    }
}

循环接收消息

package com.meng.chat;

import java.net.DatagramPacket;
import java.net.DatagramSocket;


public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        while (true){
            //准备接受包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet);//阻塞式接受包裹
            //断开
            byte[] data = packet.getData();

            String receiverData = new String(data, 0, data.length);
            System.out.println(receiverData);
            if (receiverData.equals("bye")){
                break;
            }


        }
        socket.close();
    }
}

在线咨询：双方都是接收方也是发送方

package com.meng.chat;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;

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 (Exception 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 (Exception e) {
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

package com.meng.chat;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

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 (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        while (true){
            try {
                //准备接受包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞式接受包裹
                //断开
                byte[] data = packet.getData();

                String receiverData = new String(data, 0, data.length);
                System.out.println(msgFrom+"："+receiverData);
                if (receiverData.equals("bye")){
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }


        }
        socket.close();
    }
}

package com.meng.chat;

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();
    }
}

package com.meng.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

URL

统一资源定位符：定位资源的，定位互联网上的某一个资源

DNS域名解析

协议：//ip地址：端口/项目名/资源

package com.meng.lesson04;

import java.net.MalformedURLException;
import java.net.URL;

public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=mjlh&password=111");
        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());//全路经
        System.out.println(url.getQuery());//参数
    }
}

网上的某一个资源

DNS域名解析

协议：//ip地址：端口/项目名/资源

package com.meng.lesson04;

import java.net.MalformedURLException;
import java.net.URL;

public class URLDemo01 {
    public static void main(String[] args) throws MalformedURLException {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=mjlh&password=111");
        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());//全路经
        System.out.println(url.getQuery());//参数
    }
}