【Java 网络编程】TCP/UDP 聊天实现，URL 下载网络资源_tcp通讯如何下载url链接-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_43763344/article/details/109287259

本文介绍了Java网络编程的应用案例，包括TCP和UDP聊天的实现，文件上传，以及如何利用URL下载网络资源。通过IP地址和端口定位计算机，讲解了TCP聊天案例的客户端和服务端代码，UDP发送和接收消息的实现，以及UDP多线程咨询。此外，还展示了如何使用Java进行URL资源的下载操作。

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文章目录

前言与回顾

之前总结过网络编程的基础知识，这篇文章主要总结网络实战与应用案例

计算机网络：将地理位置不同的多台计算机通过线路连接起来，在网络系统，管理软件，以及网络协议的协调下，实现资源共享和信息传递

网络编程中通过 ip 地址和 Mac 地址定位到一台或者多台计算机，然后进行 TCP /UDP 的传输方式进行通信

IP 地址

唯一定位一台计算机
IP 分类
- ipv4/ipv6
  - ipv4: 点分十进制的格式，四个字节组成，但是在 2011 就用完了
  - ipv6: 128位，8个无符号整数，由0-9，a-e 组成 2001:1111:0aaa:342b:1241:0aaa:234c:123d
- 公网(互联网)/私网(局域网)
  - 192.168.xxx.xxx 专门给组织内部使用
  - 具体的详细划分

127.0.0.1 表示本机地址

测试 IP

package Mynet;

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

/**
 * @Title:
 * @Package
 * @Description: 测试 ip
 * @author: maze
 * @date 2020/10/26下午 12:44
 */
public class TestInetAddress {
    public static void main(String[] args) {
        try {
            // 查询本机名和地址
            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);

            // 查询网址百度 ip
            InetAddress inetAddress4 = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress4);

            // 常用方法
            System.out.println(inetAddress4.getAddress());
            System.out.println(inetAddress4.getCanonicalHostName()); //获得规范的名字
            System.out.println(inetAddress4.getHostAddress()); //主机名字
            System.out.println(inetAddress4.getHostName()); //获取域名或者自己电脑名字

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

测试端口

端口号用来表示计算机上的一个进程
端口分类

公有端口 0~1023
HTTP:80, HTTPS:443,FTP:21:SSH :22 Telent:23，Tomcat:8080,MySQL：3306，Oracle:1521
程序可以用的端口号：2014~49151

public class TestInetAddress {
    public static void main(String[] args) {
        InetSocketAddress socketAddress = new InetSocketAddress("127.0.0.1", 8080);
        System.out.println(socketAddress);
        System.out.println(socketAddress.getAddress());
        System.out.println(socketAddress.getHostName());
    }
}

TCP 聊天案例

客户端

连接服务器 socket
发送消息

服务器

建立服务的端口 ServerSocket
等待用户的连接 accept
接收用户消息

服务器代码

package Mynet;

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

/**
 * @Title:
 * @Package
 * @Description: 服务端
 * @author: maze
 * @date 2020/10/26下午 14:21
 */
public class TCPServer {
    public static void main(String[] args) throws IOException {
        //1.定义一个服务器的套接字端口号
        ServerSocket socket = new ServerSocket(9090);
        //2.等待客户端连接过来
        Socket accept = socket.accept();
        //3.读取客户端消息
        InputStream inputStream = accept.getInputStream();

        //管道流
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        while((len=inputStream.read(buffer))!=-1){
            bos.write(buffer,0,len);
        }
        System.out.println(bos.toString());

        //关闭流
        bos.close();
        inputStream.close();
        accept.close();
        socket.close();
    }
}

客户端代码

package Mynet;

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

/**
 * @Title:
 * @Package
 * @Description:客户端
 * @author: maze
 * @date 2020/10/26下午 14:21
 */
public class TCPClient {
    public static void main(String[] args) throws IOException {
        // 1.要知道服务器地址
        InetAddress address = InetAddress.getByName("127.0.0.1");
        int port = 9090;
        //2.创建一个 socket 连接
        Socket socket = new Socket(address,port);
        //3.发送消息
        OutputStream outputStream = socket.getOutputStream();
        outputStream.write("你好,欢迎学习Java网络编程".getBytes());

        //关闭流
        outputStream.close();
        socket.close();
    }
}

文件上传案例

需求:现在我们要从客户端发送一张图片给服务器

客户端代码

package Mynet;

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

/**
 * @Title:
 * @Package
 * @Description:
 * @author: maze
 * @date 2020/10/26下午 15:36
 */
public class TCP2Client {
    public static void main(String[] args) throws Exception {
        //1.创建 socket 对象
        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("1.jpg"));

        //4.写出文件
        byte[] buffer = new byte[1024];
        int len = 0;
        while((len = fis.read(buffer)) !=-1){
            os.write(buffer,0,len);
        }
        // 通知服务器我结束了
        socket.shutdownOutput();

        // 确定服务器是否接收完毕
        InputStream inputStream = socket.getInputStream();
        // String byte
        ByteArrayOutputStream 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());

        // 关闭流
        baos.close();
        inputStream.close();
        fis.close();
        os.close();
        socket.close();
    }
}

服务器代码

package Mynet;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @Title:
 * @Package
 * @Description:
 * @author: maze
 * @date 2020/10/26下午 15:36
 */
public class TCP2Server {
    public static void main(String[] args) throws Exception {
        // 1.创建套接字
        ServerSocket serverSocket = new ServerSocket(9000);
        // 2.监听客户端的连接
        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("2.jpg"));
        byte[] buffer =new byte[1024];
        int len;
        while((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        //5.通知客户端接收完毕
        OutputStream os = socket.getOutputStream();
        os.write("我接收完毕了,你可以断开了".getBytes());
        //关闭资源
        os.close();
        fos.close();
        is.close();
        socket.close();
        serverSocket.close();
    }
}

UDP 发送消息

客户端代码

package Mynet;
import java.io.IOException;
import java.net.*;
/**
 * @Title:
 * @Package
 * @Description:
 * @author: maze
 * @date 2020/10/26下午 23:04
 */
public class UdpClient {
    public static void main(String[] args) throws IOException {
        //1.建立一个 socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String message = "服务器 你好";
        // 发送的对象
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        // 参数: 数据,数剧的长度,要发送的对象
        DatagramPacket packet = new DatagramPacket(message.getBytes(),0,message.getBytes().length,localhost,port);
        //3.发送包
        socket.send(packet);
        //4.关闭流
        socket.close();
    }
}

服务器代码

package Mynet;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
 * @Title:
 * @Package
 * @Description:
 * @author: maze
 * @date 2020/10/26下午 23:33
 */
public class UdpServer {
    public static void main(String[] args) throws IOException {
        // 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);

        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));
        // 关闭连接
        socket.close();
    }
}

UDP 聊天案例

客户端代码

package Mynet.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
/**
 * @Title:
 * @Package
 * @Description: 发送方
 * @author: maze
 * @date 2020/10/27下午 20:36
 */
public class UdpSenderDemo1 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        // 准备数据:控制台读取
        while(true) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

            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();
    }
}

服务器代码

package Mynet.chat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
/**
 * @Title: 
 * @Package 
 * @Description: 接收方
 * @author: maze 
 * @date 2020/10/27下午 20:37
 */
public class UdpSeviceDemo1 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        while(true){
            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);
            socket.receive(packet); //阻塞式接收

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

UDP 多线程咨询

我们要把上面的代码修改为多线程的

封装发送消息的类

package Mynet.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;

/**
 * @Title:
 * @Package
 * @Description: 发送消息的线程
 * @author: maze
 * @date 2020/10/27下午 22:09
 */
public class TalkSend implements Runnable{
    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort; // 对端端口
    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() {
        // 准备数据:控制台读取
        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();
    }
}

封装接收消息的类

package Mynet.chat;

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

/**
 * @Title:
 * @Package
 * @Description:
 * @author: maze
 * @date 2020/10/27下午 22:23
 */
public class TalkRecive implements Runnable{
    public static void main(String[] args) {

    }
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;
    public TalkRecive(int port,String msgFrom) {
        this.msgFrom = msgFrom;
        this.port = port;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while(true){
            try {
                //准备接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container,0,container.length);
                socket.receive(packet); //阻塞式接收
                //断开连接
                byte[] data = packet.getData();
                String receive = new String(data,0,data.length);

                System.out.println(msgFrom + ":" +receive);
                if(receive.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

学生端开启两个线程

public class TalkStudent {
    public static void main(String[] args) {
        new Thread(new TalkSend(7777,"localhost",9999)).start();
        new Thread(new TalkRecive(8888,"老师")).start();
    }
}

教师端开启两个线程

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

URL 下载网络资源

url : 统一资源定位符,定位互联网上的某个资源

package syn;

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

/**
 * @Title:
 * @Package
 * @Description: 下载网络资源
 * @author: maze
 * @date 2020/10/28上午 9:12
 */
public class UrlDown {
    public static void main(String[] args) throws Exception {
        // 1 下载这个地址的图片
        URL url = new URL("https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=1538415511,2500160749&fm=26&gp=0.jpg");
        //2 连接到这个资源 HTTP
        HttpURLConnection urlConnection =(HttpURLConnection)url.openConnection();

        //3.下载
        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream("1.jpg");
        byte[] buffer = new byte[1024];
        int len;
        while((len=inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}