第十六话-Java网络编程

IP

  • 唯一定位一台网络上计算机

  • 127.0.0.1 ： 本机 ：localhost

  • ip地址分类

    • ipv4/ipv6
    • ipv4：四个字节，一共42亿个
    • ipv6：128位，8个无符号整数
    • 公网（互联网）+私网（局域网）
      • ABCD类地址
      • 192.168.XX.XX，专门给组织内使用

  • 域名：记忆IP问题

package com.xie.lessonip;

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

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 inetAddress2 = InetAddress.getByName("localhost");
            System.out.println(inetAddress2);
            InetAddress inetAddress3 = InetAddress.getLocalHost();
            System.out.println(inetAddress3);
            //查询网址地址
            InetAddress inetAddress4 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress4);
        } 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
  • 规定范围0~65535
  • TCP，UDP：65535*2 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
      • Telnet：23
    • 程序注册端口：1024~49151，分配用户或程序
      • Tomcat：8080
      • Mysql：3306
      • Oracle：1521
    • 动态、私有：49152~65535
//查看所有端口
netstat -ano
//查看具体端口
netstat -ano|findstr "5900"
//查看指定端口的进程
tasklist|findstr "8696"

package com.xie.lessonip;

import java.net.InetSocketAddress;

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());
    }
}

通信协议

TCP：用户传输协议

​ - 连接稳定、三次握手、四次挥手、客服端服务端，传输完成释放连接效率低

UDP：用户数据包协议

​ - 不连接不稳定，客户端服务端没有明确界限

TCP/IP协议簇：实际是一组协议

代码DEMO

客户端

package com.xie.lessonip;

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

public class TcpClientDemo1 {
    public static void main(String[] args){
        Socket socket = null;
        OutputStream os = null;
        try {
            //1 知道服务端ip端口
            InetAddress ip = InetAddress.getByName("127.0.0.1");
            int port = 9999;
            //2 创建socket连接到服务端
            socket = new Socket(ip, port);
            //3 发送消息，IO流
            os = socket.getOutputStream();
            os.write("测试连接".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();
                }
            }
        }
    }
}

服务端

package com.xie.lessonip;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.*;

public class TcpServiceDemo1 {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        ByteArrayOutputStream baos = null;
        try {
            //1 创建服务端
            serverSocket = new ServerSocket(9999);
            while (true){
                //2 等待客户端连接
                socket = serverSocket.accept();
                //3 获取输入流，读取客户端消息
                is = socket.getInputStream();
                //4 管道流，一次打印所有读取的内容
                baos = new ByteArrayOutputStream();
                byte[] buffer = new byte[1024];
                int len;
                //5 读取内容放到管道流，实际是字节数组
                while ((len=is.read(buffer))!=-1){
                    baos.write(buffer,0,len);
                }
                //6 一次打印所有读取内容
                System.out.println(baos.toString());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            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();
                }
            }
        }
    }
}

TCP上传文件

客户端

package com.xie.lessonip;

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

public class TcpClientDemo2 {
    public static void main(String[] args) throws Exception {
        //1 创建socket连接
        Socket socket = new Socket(InetAddress.getByName("127.0.0.1"),9999);
        //2 创建输出流
        OutputStream os = socket.getOutputStream();
        //3 读取文件，写出文件
        FileInputStream fis = new FileInputStream(new File("picture.png"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len=fis.read(buffer))!=-1){
            os.write(buffer,0,len);
        }
        //通知服务器，已传送完毕
        socket.shutdownOutput();
        //接受服务器消息，确定服务器接收完毕，才能断开连接
        InputStream inputStream = socket.getInputStream();
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer2 = new byte[1024];
        int len2;
        while ((len=inputStream.read(buffer))!=-1){
            baos.write(buffer,0,len);
        }
        System.out.println(baos.toString());
        //关闭资源
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务端

package com.xie.lessonip;

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

public class TcpServiceDemo2 {
    public static void main(String[] args) throws Exception {
        // 1 创建服务
        ServerSocket serverSocket = new ServerSocket(9999);
        // 2 监听客户端连接
        Socket socket = serverSocket.accept();
        // 3 获取输入流
        InputStream is = socket.getInputStream();
        // 4 文件输出
        FileOutputStream fos = new FileOutputStream(new File("receive.png"));
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer))!=-1){
            fos.write(buffer);
        }
        // 通知客户端，我已接收完毕
        OutputStream os = socket.getOutputStream();
        os.write("我已接收完毕，你可以断开了".getBytes());

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

UDP

代码-控制台输入通信

发送端

package com.xie.chat;

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

public class UdpSendDemo1 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        //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",8888));
            socket.send(packet);
            if(data.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

接收端

package com.xie.chat;

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

public class UdpReceiveDemo1 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        while (true){
            //准备接受包裹
            byte[] buffer = new byte[1024];
            DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
            socket.receive(packet);//阻断式接收包裹
            byte[] data = packet.getData();
            //这里用packet.getLength()获取真实的接收长度，如果使用data.length则是固定1024
            System.out.println(data.length);
            String receiveData = new String(data,0,packet.getLength());
            System.out.println(receiveData);
            //bye时断开连接
            if (receiveData.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

多线程通信

发送线程

package com.xie.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;
    int fromPort;
    String toIp;
    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(toIp, toPort));
                socket.send(packet);
                if (data.equals("bye")) {
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

接收线程

package com.xie.chat;

import org.omg.CORBA.PRIVATE_MEMBER;

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

    @Override
    public void run() {
        while (true){
            try {
                //准备接受包裹
                byte[] buffer = new byte[1024];
                DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
                socket.receive(packet);//阻断式接收包裹
                byte[] data = packet.getData();
                //这里用packet.getLength()获取真实的接收长度，如果使用data.length则是固定1024
                String receiveData = new String(data,0,packet.getLength());
                System.out.println(this.msgFrom+":"+receiveData);
                //bye时断开连接
                if (receiveData.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

启动线程

package com.xie.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(6000,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"老师")).start();
    }
}

package com.xie.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(6001,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();
    }
}

URL下载网络资源

package com.xie;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class lessonURL {
    public static void main(String[] args) throws Exception {
        //1 下载地址
        URL url = new URL(
                "https://m801.music.126.net/20220501154955/1a2e333692546d47b62bbccb456a75de/jdyyaac" +
                        "/obj/w5rDlsOJwrLDjj7CmsOj/14174788417/2483/2007/6911/8b13d701f0180708efe13fc0d97c9c9c.m4a");
        //2 连接到资源
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        //3 获取输入流
        InputStream inputStream = urlConnection.getInputStream();
        //4 输出成文件
        FileOutputStream fos = new FileOutputStream("c.m4a");
        byte[] buffer = new byte[1024];
        int len;
        while ((len = inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}
posted @   少年阿川  阅读(27)  评论(0)  编辑  收藏  举报
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