Java网络编程实例——简单模拟在线聊天

需要知道简单的IO流操作，以及简单的UDP发送数据包的原理。

需要用到的类：DatagramSocket、DatagramPacket

UDP数据包基于DatagramSocket发送和接收，DatagramPacket用于封装数据包

看下案例：

客户端发送消息：

正常情况下从控制台读信息，封装到DatagramPacket之中，再由DatagramSocket的send方法发出

读取到bye的时候退出聊天

public class UdpOnlineClient { public static void main(String[] args) throws IOException {DatagramSocket socket = new DatagramSocket(10000);BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));while (true) { String data = bufferedReader.readLine(); byte[] datas = data.getBytes(); DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress('localhost', 9999)); socket.send(packet); if (data.equals('bye')){break; }}socket.close(); }}

服务端接收消息：

DatagramSocket的receive方法接收客户端发送的消息，打印到控制台，如果信息是bye则退出聊天

public class UdpOnlineServer { public static void main(String[] args) throws IOException {DatagramSocket socket = new DatagramSocket(9999);while (true){ byte[] buffer = new byte[1024]; DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length); socket.receive(packet); String msg = new String(packet.getData(), 0, packet.getLength()); System.out.println(msg); if(msg.equals('bye')){break; }}socket.close(); }}

试验：正常开启客户端和服务端后：

客户端发送消息：

服务端接收到信息即成功：

有了这个思路，我们只需要把发送和接收封装成发送类和接收类，使用多线程即可实现聊天了

创建UDP发送实现类TaskSend、UDP接收实现类TaskReceive，以及模拟多线程通信的通信类ChatThread1、ChatThread2

UDP发送实现类TaskSend：

public class TaskSend implements Runnable{ private String sendIP; //自己的服务端口 private int ownPort; private int sendPort; //读取控制台输入流 private BufferedReader bufferedReader; private DatagramSocket socket; public TaskSend(String sendIP, int ownPort, int sendPort) {this.sendIP = sendIP;this.sendPort = sendPort;try { socket = new DatagramSocket(ownPort); bufferedReader = new BufferedReader(new InputStreamReader(System.in));} catch (SocketException e) { e.printStackTrace();} finally {} } //发送消息 public void run() {while (true) { try {String data = bufferedReader.readLine();//打印自己的消息System.out.println('我：'+data);byte[] datas = data.getBytes();DatagramPacket packet = new DatagramPacket(datas, 0, datas.length,new InetSocketAddress(sendIP,sendPort));socket.send(packet);if (data.equals('bye')) { break;} } catch (IOException e) {e.printStackTrace(); } finally { }}socket.close(); }}

UDP接收实现类TaskReceive：

public class TaskReceive implements Runnable{ private int ownPort; //发送信息的人 private String msgOwner; private DatagramSocket socket; public TaskReceive(int ownPort, String msgOwner) {this.msgOwner = msgOwner;try { socket = new DatagramSocket(ownPort);} catch (SocketException e) { e.printStackTrace();} finally {} } //接收消息 public void run() {while (true) { try {byte[] buffer = new byte[1024];DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);socket.receive(packet);String msg = new String(packet.getData(), 0, packet.getLength());System.out.println(msgOwner+'：'+msg);if (msg.equals('bye')) { break;} } catch (IOException e) {e.printStackTrace(); } finally { }}socket.close(); }}

之后使用两个通信类开启多线程模拟一下：

模拟老师

public class ChatThread1 { public static void main(String[] args) {new Thread(new TaskSend('localhost',9999,10000)).start();new Thread(new TaskReceive(9998,'老师')).start(); }}

模拟学生

public class ChatThread2 { public static void main(String[] args) {new Thread(new TaskReceive(9999,'学生')).start();new Thread(new TaskSend('localhost',9998,10001)).start(); }}

实例：

学生

老师

到此简单的在线聊天功能就完成了，可以巩固一下之前学习的网络知识

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