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简述 tcp 和 udp的区别？

news 2025/8/2 21:06:55

简述 tcp 和 udp的区别？

TCP（Transmission Control Protocol）和UDP（User Datagram Protocol）是两种不同的传输层协议，用于在计算机网络中进行数据传输。以下是它们的主要区别：

区别：

连接性：
- TCP： 面向连接的协议，通过三次握手建立可靠的连接，确保数据的可靠性和完整性。
- UDP： 无连接的协议，不建立连接，发送数据时不保证可靠性和完整性。
数据传输方式：
- TCP： 提供可靠的、面向流的服务，数据被分割成小的数据块，并以字节流的形式发送。
- UDP： 无连接的，数据被分割成小的数据包，每个数据包独立发送。
可靠性：
- TCP： 提供可靠的传输，通过确认机制和重传机制来确保数据的可靠性。
- UDP： 不提供可靠性，数据包可能会丢失或无序。
效率：
- TCP： 由于提供可靠性，数据传输会有一定的开销，适用于对数据传输要求较高的场景。
- UDP： 无连接，传输效率高，适用于对实时性要求较高、可以容忍少量数据丢失的场景。

代码示例：

以下是Java中使用TCP和UDP进行简单通信的示例。

TCP 示例：

// 服务器端
import java.io.*;
import java.net.*;public class TCPServer {public static void main(String[] args) {try {ServerSocket serverSocket = new ServerSocket(12345);System.out.println("Waiting for client...");Socket clientSocket = serverSocket.accept();System.out.println("Client connected.");BufferedReader reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));String message = reader.readLine();System.out.println("Received from client: " + message);PrintWriter writer = new PrintWriter(clientSocket.getOutputStream(), true);writer.println("Hello from server!");reader.close();writer.close();clientSocket.close();serverSocket.close();} catch (IOException e) {e.printStackTrace();}}
}

// 客户端
import java.io.*;
import java.net.*;public class TCPClient {public static void main(String[] args) {try {Socket socket = new Socket("localhost", 12345);PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);writer.println("Hello from client!");BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));String response = reader.readLine();System.out.println("Received from server: " + response);writer.close();reader.close();socket.close();} catch (IOException e) {e.printStackTrace();}}
}

UDP 示例：

// 服务器端
import java.io.*;
import java.net.*;public class UDPServer {public static void main(String[] args) {try {DatagramSocket serverSocket = new DatagramSocket(9876);System.out.println("Waiting for client...");byte[] receiveData = new byte[1024];DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);serverSocket.receive(receivePacket);String message = new String(receivePacket.getData(), 0, receivePacket.getLength());System.out.println("Received from client: " + message);InetAddress clientAddress = receivePacket.getAddress();int clientPort = receivePacket.getPort();byte[] sendData = "Hello from server!".getBytes();DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, clientAddress, clientPort);serverSocket.send(sendPacket);serverSocket.close();} catch (IOException e) {e.printStackTrace();}}
}

// 客户端
import java.io.*;
import java.net.*;public class UDPClient {public static void main(String[] args) {try {DatagramSocket clientSocket = new DatagramSocket();InetAddress serverAddress = InetAddress.getByName("localhost");int serverPort = 9876;String message = "Hello from client!";byte[] sendData = message.getBytes();DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, serverAddress, serverPort);clientSocket.send(sendPacket);byte[] receiveData = new byte[1024];DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);clientSocket.receive(receivePacket);String response = new String(receivePacket.getData(), 0, receivePacket.getLength());System.out.println("Received from server: " + response);clientSocket.close();} catch (IOException e) {e.printStackTrace();}}
}