Java网络编程：TCP/UDP通信示例

原创客官°小女子只卖身不卖艺 2024-11-06 23:48 32阅读 0赞

Java网络编程中，TCP和UDP是两种常用的通信协议。下面我将分别给出TCP和UDP通信的简单示例代码。

### TCP通信示例TCP（传输控制协议）是一种面向连接的、可靠的、基于字节流的传输层通信协议。在Java中，可以使用`ServerSocket`和`Socket`类来实现TCP通信。

**服务器端（Server）:**

```javaimport java.io.*;
import java.net.*;

public class TCPServer {
 public static void main(String[] args) {
 try {
ServerSocket serverSocket = new ServerSocket(1234); //监听1234端口 System.out.println("Server is running and waiting for client connection...");

//等待客户端连接Socket clientSocket = serverSocket.accept();
 System.out.println("Client connected.");

// 获取输入输出流 BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
 PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

//读取客户端发送的消息String inputLine;
 while ((inputLine = in.readLine()) != null) {
 System.out.println("Client says: " + inputLine);

//向客户端发送消息out.println("Server received your message: " + inputLine);
 }

// 关闭连接in.close();
out.close();
 clientSocket.close();
 serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
 }
 }
}
```**客户端（Client）:**

```javaimport java.io.*;
import java.net.*;

public class TCPClient {
 public static void main(String[] args) {
 try {
//连接服务器Socket socket = new Socket("localhost",1234);
 System.out.println("Connected to server.");

// 获取输入输出流 BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
 PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
 BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

String userInput;
 while ((userInput = stdIn.readLine()) != null) {
//向服务器发送消息out.println(userInput);

//读取服务器响应String fromServer = in.readLine();
 System.out.println("Server says: " + fromServer);
 }

// 关闭连接in.close();
out.close();
 stdIn.close();
 socket.close();
} catch (UnknownHostException e) {
 System.err.println("Don't know about host " + "localhost");
e.printStackTrace();
} catch (IOException e) {
 System.err.println("Couldn't get I/O for the connection to " + "localhost");
e.printStackTrace();
 }
 }
}
```### UDP通信示例UDP（用户数据报协议）是一种无连接的协议，它在IP主机之间提供一种简单、快速的包传输服务。

**服务器端（Server）:**

```javaimport java.net.*;

public class UDPServer {
 public static void main(String[] args) {
 try {
 DatagramSocket serverSocket = new DatagramSocket(1234);
 System.out.println("Server is running and waiting for client message...");

byte[] receiveData = new byte[1024];
byte[] sendData = new byte[1024];

while (true) {
 DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
 serverSocket.receive(receivePacket);

String sentence = new String(receivePacket.getData(),0, receivePacket.getLength());
 System.out.println("RECEIVED: " + sentence);

String capitalizedSentence = sentence.toUpperCase();
 sendData = capitalizedSentence.getBytes();

DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, receivePacket.getAddress(), receivePacket.getPort());
 serverSocket.send(sendPacket);
 }
} catch (Exception e) {
e.printStackTrace();
 }
 }
}
```**客户端（Client）:**

```javaimport java.net.*;

public class UDPClient {
 public static void main(String[] args) {
 try {
 DatagramSocket clientSocket = new DatagramSocket();
 System.out.println("Client is running and waiting for user input...");

byte[] sendData = new byte[1024];
byte[] receiveData = new byte[1024];

BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

String sentence;
 while (true) {
 sentence = stdIn.readLine();
 sendData = sentence.getBytes();

InetAddress IPAddress = InetAddress.getByName("localhost");
 DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress,1234);
 clientSocket.send(sendPacket);

DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
 clientSocket.receive(receivePacket);

String modifiedSentence = new String(receivePacket.getData(),0, receivePacket.getLength());
 System.out