【Java 网络编程】TCP/UDP 聊天实现，URL 下载网络资源

我会带着你远行 2022-12-18 08:58 152阅读 0赞

### 文章目录 ###

*   *  前言与回顾
     *  测试 IP
     *  测试端口
     *  TCP 聊天案例
     *  文件上传案例
     *  UDP 发送消息
     *  UDP 聊天案例
     *  UDP 多线程咨询
     *  URL 下载网络资源

## 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][Link 1]

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();
        }
    }

[Link 1]: https://blog.csdn.net/qq_43763344/article/details/96468263