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Java——网络编程

计算机系统维护 • 2022-12-17 • 随笔 • 阅读 9

Java——网络编程,第1张

Java——网络编程

文章目录
  • 1、IP地址
  • 2、端口
  • 3、TCP协议实现聊天
  • 4、TCP实现文件上传
  • 5、UDP发送消息
  • 6、UDP实现聊天
  • 7、URL下载网络资源

1、IP地址
  • 本机IP地址：127.0.0.1、localhost
  • 域名：域名是IP相绑定
  • IP相关的代码
package network;

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

//测试IP
public class TestInetaddress {
    public static void main(String[] args) {
        try {
            //查询本机地址
            InetAddress localHost = InetAddress.getByName("localhost");
            System.out.println(localHost);
            //查询网络地址
            InetAddress baidu = InetAddress.getByName("www.baidu.com");
            System.out.println(baidu);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
    }
}
  • 运行结果
2、端口
  • 端口表示计算机上的一个程序的进程
    1. 不同的进程有不同的端口号，用来区分软件；
    2. 被规定0~65532
    3. TCP，UDP：单个协议号不能冲突
    4. 公用端口：0~1023
  • 代码演示
package network;

import java.net.InetSocketAddress;

public class TestIntSocketAddress {
    public static void main(String[] args) {
        //获取端口
        InetSocketAddress localhost = new InetSocketAddress("localhost", 8080);
        System.out.println(localhost);
        System.out.println(localhost.getAddress());     //获取IP地址
        System.out.println(localhost.getHostName());    //获取域名
        System.out.println(localhost.getPort());    //获取端口号
    }
}
  • 运行结果
3、TCP协议实现聊天
  • 客户端
    1. 连接服务器Socket
    2. 发送消息
  • 代码演示
package network;

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;
        try {
            //1.连接服务器地址
            InetAddress serverIP = InetAddress.getByName("localhost");
            int port=537;
            //2.创建一个socket连接
            socket = new Socket(serverIP,port);
            //3.发送消息
            os = socket.getOutputStream();
            os.write("Java学不会".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. 建立服务的端口ServerSocket
    2. 等待用户连接accept
    3. 接受客户端消息
  • 代码演示
package network;

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

//服务器
public class TcpServerdemo01 {
    public static void main( String[] args ) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        ByteArrayOutputStream baos = null;
        InputStream is = null;
        while (true) {
            try {
                //1.得有一个地址
                serverSocket = new ServerSocket(537);
                //2.接受消息
                socket = serverSocket.accept();
                //3.获取客户端消息
                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{
                //关闭流   先开后关
                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();
                    }
                }
            }
        }
    }
}
  • 运行结果
4、TCP实现文件上传
  • 客户端
package network;

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

public class TcpClientDemo02 {
    public static void main( String[] args ) {
        Socket socket = null;
        OutputStream os = null;
        FileInputStream fis = null;
        InputStream inputStream = null;
        ByteArrayOutputStream baos = null;
        try {
            //1.创建一个Socket连接
            socket = new Socket(InetAddress.getByName("localhost"), 537);
            //2.创建一个输出流
            os = socket.getOutputStream();
            //3.读取文件
            fis = new FileInputStream(new File("1.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();//已经传输完了
            //确定服务器以接收，再断开连接
            inputStream = socket.getInputStream();
            baos = new ByteArrayOutputStream();
            byte[] buffer2 = new byte[1024];
            int len2;
            while((len2=inputStream.read(buffer2))!=-1){
                baos.write(buffer2,0,len2);
            }
            System.out.println(baos.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            //5.关闭资源
            if(baos!=null){
                try {
                    baos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fis!=null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(os!=null){
                try {
                    os.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}
  • 服务器端
package network;

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

public class TestServerDemo02 {
    public static void main( String[] args ) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        InputStream is = null;
        FileOutputStream fos = null;
        OutputStream os = null;
        try {
            //1.创建一个服务端口
            serverSocket = new ServerSocket(537);
            //2.接听客户端的连接
            socket = serverSocket.accept();//阻断式监听，一直等待客户端连接
            //3.获取输入流
            is = socket.getInputStream();
            //4.文件输出
            fos = new FileOutputStream(new File("接收.jpg"));
            byte[] buffer = new byte[1024];
            int len;
            while((len=is.read(buffer))!=-1){
                fos.write(buffer,0,len);
            }
            //通知客户端接收完毕
            os = socket.getOutputStream();
            os.write("over".getBytes());
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            //5.关闭资源
            if(fos!=null){
                try {
                    fos.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();
                }
            }
        }
    }
}
  • 运行结果
5、UDP发送消息
  • 发送端代码
package network;

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

//不需要服务器
public class UdpclientDemo01 {
    public static void main( String[] args ) {
        DatagramSocket socket = null;
        InetAddress localhost = null;
        DatagramPacket packet = null;
        try {
            //1.建立一个Socket
            socket = new DatagramSocket();
            //2.建个包
            String msg = "Java学不会";
            //3.发给谁
            localhost = InetAddress.getByName("localhost");
            int port = 537;
            //数据,数据的长度其实，要发送给谁
            packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
            //4.发送包
            socket.send(packet);
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            //5.关闭流  不需要关闭包
            if(socket!=null){
                socket.close();
            }

        }

    }
}
  • 接收端代码
package network;

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

//还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main( String[] args ) {
        DatagramSocket socket=null;
        try {
            //1.开放端口
            socket = new DatagramSocket(537);
            //2.接收数据包
            byte[] buffer = new byte[1024];
            DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
            socket.receive(packet);//阻塞接收
            System.out.println(new String(packet.getData(),0,packet.getLength()));
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            //3.关闭资源
            if(socket!=null){
                socket.close();
            }
        }
    }
}
  • 运行结果
6、UDP实现聊天
  • 两个都是接收端，两个都是发送端
  • 创建两个线程
  1. 发送端线程
package network;

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

    @Override
    public void run( ) {
        //准备数据: 控制台读取Ststem.in
        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();
    }
}
  1. 接收端线程
package network;

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

public class TalkRecevie implements Runnable{
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;

    public TalkRecevie( 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 {
                //准备接收消息
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞接收
                //断开连接
                String receiveData = new String(packet.getData(),0,packet.getLength());
                System.out.println(msgFrom+receiveData);
                if(receiveData.equals("over")){
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }


        }
        //关闭资源
        socket.close();
    }
}
  • 创建两个客户端
  1. 学生端
package network;

public class TalkStudent {
    public static void main( String[] args ) {
        //开启两个线程
        new Thread(new Talksend(8888,"localhost",9999)).start();
        new Thread(new TalkRecevie(7777,"学生:")).start();
    }
}
  1. 老师端
package network;

public class TalkTeacher {
    public static void main( String[] args ) {
        new Thread(new Talksend(5555,"localhost",7777)).start();
        new Thread(new TalkRecevie(9999,"老师:")).start();
    }
}
  • 运行结果
7、URL下载网络资源
  • URL：统一资源定位符，定位资源。
协议://ip地址:端口号/项目名/资源

package network;

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

public class UrlDemo {
    public static void main( String[] args ) throws Exception {
        //1.下载地址
        URL url = new URL("https://m10.music.126.net/20220104173853/f67c6ebdd42e82b76676b36e0a56a8bb/ymusic/0e0e/070c/030e/9d372a7aec0fbbca8d764d2261cacb1d.mp3");
        //2.连接到这个资源 http
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        InputStream inputStream = urlConnection.getInputStream();
        
        FileOutputStream fos = new FileOutputStream("1.mp3");
        byte[] buffer = new byte[1024];
        int len;
        while((len=(inputStream.read(buffer)))!=-1){
            fos.write(buffer,0,len);
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}
  • 运行结果

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原文地址: http://outofmemory.cn/zaji/5697229.html

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