java网络编程

网络编程

1.概述

网络编程的目的：传播交流信息，数据交换

想要达到的效果：1. 如何准确得得得定位网络上的一台主机，ip+端口

							2. 如何传输数据

javaweb：网页编程 B/S

网络编程：TCP/IP C/S

1.2 ip

ip：地址：InetAddress

• 唯一定位一台网络上的计算机

• 127.0.0.1：本机地址

• ip地址得到分类：

  • ipv4 ipv6

    • ipv4 127.0.0.1，四个字节组成

    • ipv6 128位， 8个无符号整数

      2001:0bb2：aaaa：0015:0000:0000:1aaa：1312
      

  • 公网（互联网） 私网（局域网）

    • 192.168.xx.xx：专门给组织内部使用
    • ABCD类

  package com.ljb.demo1;
  
  import com.sun.jmx.snmp.InetAddressAcl;
  
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  
  //测试ip
  public class TestInetAddress {
      public static void main(String[] args) {
          try {
              //查询本地地址
              InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
              System.out.println(inetAddress);
              InetAddress inetAddress2 = InetAddress.getByName("localhost");
              System.out.println(inetAddress2);
  
              //查询网址的ip地址
              InetAddress inetAddress3 = InetAddress.getByName("www.baidu.com");
              System.out.println(inetAddress3);
  
              //常用方法
              System.out.println(inetAddress3.getHostAddress());
              System.out.println(inetAddress3.getCanonicalHostName());//规范的名字ip
              System.out.println(inetAddress3.getHostName());//
  
  
          } catch (UnknownHostException e) {
              e.printStackTrace();
          }
      }
  }
  

1.3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

• 被规定0-65535

• 单个协议不能冲突

• 端口分类

  • 公有端口 0-1023

    • http：80
    • https：443
    • ftp：21
    • telent：23

  • 程序注册端口

    • Tomcat：8080
    • MySQL：3306
    • Oracle：1521

  • 动态私有：49152-65535

    netsat -ano # 查所有的端口
    netsat -ano|findstr "5900"  # 查指定的端口
    tasklist|findstr "5900"  # 查看指定端口的进程
    ctrl+shift + esc
    

package com.ljb.demo1;

import java.net.InetSocketAddress;

public class TestInetSocketAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        InetSocketAddress socket = new InetSocketAddress("localhost", 8080);
        System.out.println(socketAddress);
        System.out.println(socket);
        System.out.println(socket.getPort());//端口
        System.out.println(socket.getHostName());//地址
        System.out.println(socket.getHostString());
    }
}

1.4通信协议

协议：约定，就好比我们之间的谈话

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/UDP：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

TCP/UDP 对比：

TCP：打电话

• 连接：稳定

• 三次握手，四次握手

  最少需要三次，保证稳定连接
  A:你愁啥
  B:瞅你咋地
  A:干一场
      
  
  A:我要走了
  B:你真的要走了码
  A:我真的要走了
  B：那你走吧
  

• 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，都可以发给您
• 导弹
• DDOS：洪水攻击！（饱和攻击）

1.5 TCP实现通信

客户端：

1. 连接服务器Socket
2. 发送消息

服务端：

1. 建立服务的端口ServerSocket
2. 等待用户的连接accept
3. 接收用户的消息

package com.ljb.demo2;

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

public class TestServer {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream bos = null;
        try {
            //1.我得有一个地址
            serverSocket = new ServerSocket(9696);
            while (true){
                //2.等待客户端连接
                socket = serverSocket.accept();
                //3.获取客户端的信息
                is = socket.getInputStream();

                //管道流
                bos = new ByteArrayOutputStream();
                byte[] b = new byte[1024];
                int len;
                while ((len=is.read(b))!=1){
                    bos.write(b, 0, len);
                }
                System.out.println(bos.toString());
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            //关闭资源
            if (bos!=null){
                try {
                    bos.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 {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

package com.ljb.demo2;

import java.io.IOException;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

//客户端
public class TestClient {
    public static void main(String[] args) {
        Socket socket = null;
        OutputStream os = null;
        try {
            //1.要知道服务器的地址
            InetAddress address = InetAddress.getByName("127.0.0.1");
            //2.创建一个socket连接
            socket = new Socket(address,9696);
            //3.发送消息
            os = socket.getOutputStream();
            os.write("你好， 李锦彪".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();
                }
            }
        }

    }
}

1.5.1 文件上传

服务端

package com.ljb.demo3;

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

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

        //1、创建服务
        ServerSocket serverSocket = new ServerSocket(9696);

        //2、监听客户端的连接
        Socket socket = serverSocket.accept();//阻塞式
        //3、获取输入流
        InputStream is = socket.getInputStream();

        //4、文件输出
        FileOutputStream fos = new FileOutputStream("receive.png");
        byte[] bytes = new byte[1024];
        int len;
        while ((len=is.read(bytes))!=-1){
            fos.write(bytes, 0, len);
        }

        //通知客户端我接受完毕
        OutputStream os = socket.getOutputStream();
        os.write("我接受完毕，小老弟".getBytes());

        // 5、关闭连接
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();

    }
}

客户端

package com.ljb.demo3;

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

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

        //1、创建一个socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"), 9696);

        //2、创建一个输出流
        OutputStream os = socket.getOutputStream();

        //3、获取文件
        FileInputStream fis = new FileInputStream(new File("D:\\IDEA Store\\网络编程学习\\src\\A-女白.png"));

        //4、写出文件
        byte[] bytes = new byte[1024];
        int len;
        while ((len=fis.read(bytes))!=-1){
            os.write(bytes, 0, len);
        }

        //通知服务器已经接收完了
        socket.shutdownOutput();//我已经传输完了

        //确定服务端接收完毕、
        InputStream is = socket.getInputStream();
        //String byte[]
        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        byte[] bytes1 = new byte[1024];
        int len2;
        while ((len2=is.read(bytes1))!=-1){
            baos.write(bytes1, 0, len2);
        }
        System.out.println(baos.toString());

        //5、关闭连接
        baos.close();
        fis.close();
        os.close();
        socket.close();

    }
}

1.6 UDP消息发送

发短信，导弹

服务端

package com.ljb.demo4;

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

//还是要等待客户端的连接
public class Udpserver {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9696);
        //接收数据包
        byte[] bytes = new byte[1024];
        DatagramPacket dp = new DatagramPacket(bytes, 0, bytes.length);

        socket.receive(dp);

        System.out.println(new String(dp.getData()));

    }
}

客户端

package com.ljb.demo4;

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

//不需要连接服务器
public class Udpclient {
    public static void main(String[] args) throws Exception {

        //1、建立一个socket
        DatagramSocket socket = new DatagramSocket();

        //2、建个包
        String msg = "你好啊， 李锦彪";

        //发送给谁
        InetAddress inetAddress = InetAddress.getByName("127.0.0.1");
        int port = 9696;
        //数据，数据的长度起始， 要发送给谁
        DatagramPacket dp = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, inetAddress, port);

        //发送包
        socket.send(dp);

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

1.6.1咨询

receive

package com.ljb.demo5;

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

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

        while (true){
            //准备接收
            byte[] bytes = new byte[1024];
            DatagramPacket dp = new DatagramPacket(bytes, 0, bytes.length);
            socket.receive(dp);//阻塞式接收包裹

            //断开连接
            byte[] data = dp.getData();
            String receiveData = new String(data, 0, data.length).trim();//trim()去掉多余的字节

            System.out.println(receiveData);

            if (receiveData.equals("0")){
                break;
            }
        }
        socket.close();
    }
}

sender

package com.ljb.demo5;

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

public class UdpSender {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(9696);

        //准备数据，控制台读取
        System.out.println("请输入：");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        while (true){
            String data = br.readLine();
            byte[] bytes = data.getBytes();
            DatagramPacket dp = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress("localhost", 6666));

            socket.send(dp);
            if (data.equals("0")){
                break;
            }
        }
        socket.close();
    }
}

对话线程

package com.ljb.demo5;

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.ljb.demo5;

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();

    }
}

receive

package com.ljb.demo5;

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 msgName;

    public TalkReceive(int port, String msgName) {
        this.port = port;
        this.msgName = msgName;

        try {
            socket = new DatagramSocket(port);

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

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

                //断开连接
                byte[] data = dp.getData();
                String receiveData = new String(data, 0, data.length).trim();//trim()去掉多余的字节

                System.out.println(msgName+"："+receiveData);

                if (receiveData.equals("0")){
                    break;
                }
            }catch (Exception e){
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

sender

package com.ljb.demo5;

import java.io.BufferedReader;
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 br = 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(this.fromport);
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        //准备数据，控制台读取
        while (true){
            try {
                String data = br.readLine();
                byte[] bytes = data.getBytes();
                DatagramPacket dp = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress(this.toip, this.toport));

                socket.send(dp);
                if (data.equals("0")){
                    break;
                }
            }catch (Exception e){
                e.printStackTrace();
            }

        }
        socket.close();
    }

}

1.7 URL

https://www.baidu.com/
协议：//ip地址：端口/项目名/资源

1.7.1下载

}

@Override
public void run() {
    //准备数据，控制台读取
    while (true){
        try {
            String data = br.readLine();
            byte[] bytes = data.getBytes();
            DatagramPacket dp = new DatagramPacket(bytes, 0, bytes.length, new InetSocketAddress(this.toip, this.toport));

            socket.send(dp);
            if (data.equals("0")){
                break;
            }
        }catch (Exception e){
            e.printStackTrace();
        }

    }
    socket.close();
}

}

### 1.7 URL

https://www.baidu.com/
协议：//ip地址：端口/项目名/资源

#### 1.7.1下载

![image-20220423170422682](https://img-blog.csdnimg.cn/img_convert/e820c2bd107380eae9b0585db9612aa4.png)