Java之UDP编程浅析

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最新推荐文章于 2025-05-26 17:50:29 发布

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分类专栏： Java

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本文展示了如何使用Java实现UDP协议的简单客户端和服务器。客户端创建数据并发送到指定IP和端口，服务器则监听特定端口接收数据，并打印接收到的信息。通过`DatagramSocket`和`DatagramPacket`类，无需建立连接即可进行数据交换。

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一. UDP协议发送数据：

创建发送端socket对象
创建数据并把数据打包
调用socket对象的发送方法发送数据包
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二. UDP协议接收数据：

创建发送端socket对象（需要指定端口）
创建一个数据包（接收容器）
调用socket对象的接收方法接收数据
解析数据并显示在控制台
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UDP协议不需要建立连接，实例如下:

public class UdpServer {

    public static void main(String[] args) {
        try {
            DatagramSocket datagramSocket = new DatagramSocket(10000);
            byte[] buf = new byte[1024];
            DatagramPacket datagramPacket = new DatagramPacket(buf, buf.length);
            while (true) {
                datagramSocket.receive(datagramPacket);
                System.out.println("ip:" + datagramPacket.getAddress().getHostAddress());
                System.out.println("接收信息:" + new String(datagramPacket.getData(), 0, datagramPacket.getLength()));
            }
        } catch (SocketException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}
public class UdpClient {

    public static void main(String[] args) {
        try {
            DatagramSocket datagramSocket = new DatagramSocket();
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            System.out.println("请输入：");
            String line = null;
            while ((line = reader.readLine()) != null) {
                byte[] bytes = line.getBytes();
                DatagramPacket datagramPacket = new DatagramPacket(bytes, bytes.length, InetAddress.getByName("127.0.0.1"), 10000);
                // 发送数据
                datagramSocket.send(datagramPacket);
                datagramSocket.close();
            }
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

public class UdpUtil {

    public DatagramSocket socketServer = null;

    private String ip;

    private int serverPort;

    public UdpUtil() {
    }

    public UdpUtil(int serverPort) {
        this.serverPort = serverPort;
    }

    public UdpUtil(String ip, int serverPort) {
        this.ip = ip;
        this.serverPort = serverPort;
    }

    public void connect() throws Exception {
        try {
            if (socketServer != null) {
                socketServer.close();
            }
            socketServer = new DatagramSocket(serverPort);
            socketServer.setReceiveBufferSize(1024 * 200);
            System.out.println("UDPServer connect success.");
        } catch (Exception e) {
            if (socketServer != null) {
                socketServer.close();
                socketServer = null;
            }
            throw new Exception("Connect failed. " + e.getMessage());
        }
    }

    public void connect(int port) throws Exception {
        try {
            if (socketServer != null) {
                socketServer.close();
            }
            socketServer = new DatagramSocket(port);
            socketServer.setReceiveBufferSize(1024 * 200);
            System.out.println("UDPServer connect success.");
        } catch (SocketException e) {
            if (socketServer != null) {
                socketServer.close();
                socketServer = null;
            }
            throw new Exception("Connect failed." + e.getMessage());
        }
    }

    public DatagramPacket collectDatagramPacket(int dataLength) throws IOException {
        byte[] data = new byte[dataLength];
        DatagramPacket dPacket = new DatagramPacket(data, dataLength);
        socketServer.receive(dPacket);
        return dPacket;
    }

    public byte[] collect(int dataLength) throws IOException {
        byte[] data = new byte[dataLength];
        DatagramPacket dPacket = new DatagramPacket(data, dataLength);
        socketServer.receive(dPacket);
        return data;
    }

    public byte[] collect(int dataLength, String ip1, String ip2) throws Exception {
        byte[] data = new byte[dataLength];
        DatagramPacket dPacket = new DatagramPacket(data, dataLength);
        socketServer.receive(dPacket);
        if (ip1 != null || ip2 != null) {
            if (dPacket.getAddress().getHostAddress().equals(ip1) || dPacket.getAddress().getHostAddress().equals(ip2)) {
                return data;
            } else {
                return null;
            }
        } else {
            return data;
        }
    }

    public void send(DatagramPacket datagramPacket) throws Exception {
        socketServer.send(datagramPacket);
    }

    public void send(byte[] data) throws IOException {
        DatagramPacket datagramPacket = new DatagramPacket(data, data.length, InetAddress.getByName(ip), serverPort);
        socketServer.send(datagramPacket);
    }

}