什么是TCP/IP和UDP 代码示例(java 架构)
和是两种常用的传输层协议,用于在网络上发送和接收数据。
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TCP/IP 和 UDP 概述
TCP/IP (Transmission Control Protocol/Internet Protocol) 和 UDP (User Datagram Protocol) 是两种常用的传输层协议,用于在网络上发送和接收数据。
TCP/IP (传输控制协议/互联网协议)
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特点:
- 面向连接:在数据传输之前需要建立连接。
- 可靠传输:通过确认机制、重传机制、流量控制和拥塞控制来确保数据的可靠传输。
- 有序传输:数据包按顺序到达接收端。
- 流量控制:防止发送方发送过快导致接收方无法处理。
- 拥塞控制:避免网络拥塞。
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应用场景:适用于需要高可靠性的应用,如文件传输、电子邮件、网页浏览等。
UDP (用户数据报协议)
-
特点:
- 无连接:不需要预先建立连接,发送数据前不需要握手。
- 不可靠传输:没有确认机制,数据包可能丢失或乱序到达。
- 低延迟:由于没有复杂的控制机制,传输速度更快。
- 简单高效:协议开销小,适合实时应用。
-
应用场景:适用于对实时性要求较高且可以容忍一定数据丢失的应用,如视频会议、在线游戏、VoIP等。
Java代码示例
TCP/IP 示例
服务器端代码
import java.io.*;
import java.net.*;
public class TCPServer {
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = new ServerSocket(8080);
System.out.println("TCP Server started on port 8080");
while (true) {
Socket clientSocket = serverSocket.accept();
System.out.println("New client connected");
// 创建新线程处理每个客户端连接
new Thread(new ClientHandler(clientSocket)).start();
}
}
static class ClientHandler implements Runnable {
private final Socket clientSocket;
public ClientHandler(Socket socket) {
this.clientSocket = socket;
}
@Override
public void run() {
try (
PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()))
) {
String inputLine;
while ((inputLine = in.readLine()) != null) {
System.out.println("Received from client: " + inputLine);
out.println("Echo: " + inputLine);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
clientSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
客户端代码
import java.io.*;
import java.net.*;
public class TCPClient {
public static void main(String[] args) throws IOException {
String host = "localhost";
int port = 8080;
Socket socket = new Socket(host, port);
System.out.println("Connected to TCP Server");
try (
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))
) {
String userInput;
while ((userInput = stdIn.readLine()) != null) {
out.println(userInput);
System.out.println("Server response: " + in.readLine());
}
} finally {
socket.close();
}
}
}
UDP 示例
服务器端代码
import java.io.*;
import java.net.*;
public class UDPServer {
public static void main(String[] args) throws IOException {
DatagramSocket serverSocket = new DatagramSocket(9090);
byte[] receiveData = new byte[1024];
System.out.println("UDP Server started on port 9090");
while (true) {
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
String receivedData = new String(receivePacket.getData(), 0, receivePacket.getLength());
System.out.println("Received from client: " + receivedData);
// 回复客户端
byte[] sendData = ("Echo: " + receivedData).getBytes();
InetAddress clientAddress = receivePacket.getAddress();
int clientPort = receivePacket.getPort();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, clientAddress, clientPort);
serverSocket.send(sendPacket);
}
}
}
客户端代码
import java.io.*;
import java.net.*;
public class UDPClient {
public static void main(String[] args) throws IOException {
String host = "localhost";
int port = 9090;
DatagramSocket clientSocket = new DatagramSocket();
InetAddress serverAddress = InetAddress.getByName(host);
System.out.println("Connected to UDP Server");
try (
BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))
) {
String userInput;
while ((userInput = stdIn.readLine()) != null) {
// 发送数据到服务器
byte[] sendData = userInput.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, serverAddress, port);
clientSocket.send(sendPacket);
// 接收服务器的回复
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clientSocket.receive(receivePacket);
String receivedData = new String(receivePacket.getData(), 0, receivePacket.getLength());
System.out.println("Server response: " + receivedData);
}
} finally {
clientSocket.close();
}
}
}
解释
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TCP/IP 示例:
- 服务器端:使用
ServerSocket
监听指定端口,接受客户端连接,并为每个连接创建一个新线程来处理请求。 - 客户端:连接到服务器,发送数据并接收服务器的回复。
- 服务器端:使用
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UDP 示例:
- 服务器端:使用
DatagramSocket
监听指定端口,接收客户端的数据包,并回复客户端。 - 客户端:发送数据包到服务器,并接收服务器的回复。
- 服务器端:使用
这两个示例分别展示了如何在Java中使用TCP/IP和UDP进行网络通信。TCP/IP适用于需要可靠传输的场景,而UDP适用于对实时性要求较高的场景。
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