????????网络编程是现代软件开发中不可或缺的一部分，它使得我们能够通过网络连接和交互，实现数据传输和通信。Java作为一种广泛应用于网络编程的编程语言，提供了丰富的库和工具，使得开发者能够轻松地构建强大的网络应用程序。本文将详细介绍Java网络编程的基础知识，包括套接字、TCP和UDP协议、客户端和服务器端编程等，并提供相关示例代码，帮助读者快速上手。
????????在Java网络编程中，套接字(Socket)是实现网络通信的基本构建块。套接字提供了一种机制，使得不同主机上的进程能够通过网络进行通信。Java提供了java.net包，其中的Socket类和ServerSocket类分别用于客户端和服务器端的套接字编程。
示例代码：
// 客户端代码
import java.io.*;
import java.net.*;
public class Client {
public static void main(String[] args) {
try {
Socket socket = new Socket("服务器IP地址", 12345);
// 发送数据
OutputStream outputStream = socket.getOutputStream();
PrintWriter writer = new PrintWriter(outputStream);
writer.println("Hello, Server!");
writer.flush();
// 接收数据
InputStream inputStream = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String response = reader.readLine();
System.out.println("Server response: " + response);
// 关闭连接
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
// 服务器端代码
import java.io.*;
import java.net.*;
public class Server {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(12345);
System.out.println("Server started, waiting for client...");
Socket socket = serverSocket.accept();
System.out.println("Client connected.");
// 接收数据
InputStream inputStream = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String request = reader.readLine();
System.out.println("Client request: " + request);
// 发送数据
OutputStream outputStream = socket.getOutputStream();
PrintWriter writer = new PrintWriter(outputStream);
writer.println("Hello, Client!");
writer.flush();
// 关闭连接
socket.close();
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
????????在网络编程中，TCP和UDP是两种常用的传输协议。TCP协议提供可靠的、面向连接的数据传输，而UDP协议则提供不可靠的、无连接的数据传输。Java网络编程中可以使用Socket和ServerSocket类来实现TCP协议的通信，使用DatagramSocket和DatagramPacket类来实现UDP协议的通信。
TCP通信示例代码：
// TCP客户端代码
import java.io.*;
import java.net.*;
public class TCPClient {
public static void main(String[] args) {
try {
Socket socket = new Socket("服务器IP地址", 12345);
// 发送数据
OutputStream outputStream = socket.getOutputStream();
PrintWriter writer = new PrintWriter(outputStream);
writer.println("Hello, Server!");
writer.flush();
// 接收数据
InputStream inputStream = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String response = reader.readLine();
System.out.println("Server response: " + response);
// 关闭连接
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
// TCP服务器端代码
import java.io.*;
import java.net.*;
public class TCPServer {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(12345);
System.out.println("Server started, waiting for client...");
Socket socket = serverSocket.accept();
System.out.println("Client connected.");
// 接收数据
InputStream inputStream = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
String request = reader.readLine();
System.out.println("Client request: " + request);
// 发送数据
OutputStream outputStream = socket.getOutputStream();
PrintWriter writer = new PrintWriter(outputStream);
writer.println("Hello, Client!");
writer.flush();
// 关闭连接
socket.close();
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
UDP通信示例代码：
// UDP客户端代码
import java.io.*;
import java.net.*;
public class UDPClient {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket();
// 发送数据
String message = "Hello, Server!";
byte[] sendData = message.getBytes();
InetAddress serverAddress = InetAddress.getByName("服务器IP地址");
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, serverAddress, 12345);
socket.send(sendPacket);
// 接收数据
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
socket.receive(receivePacket);
String response = new String(receivePacket.getData(), 0, receivePacket.getLength());
System.out.println("Server response: " + response);
// 关闭连接
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
// UDP服务器端代码
import java.io.*;
import java.net.*;
public class UDPServer {
public static void main(String[] args) {
try {
DatagramSocket socket = new DatagramSocket(12345);
System.out.println("Server started, waiting for client...");
// 接收数据
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
socket.receive(receivePacket);
String request = new String(receivePacket.getData(), 0, receivePacket.getLength());
System.out.println("Client request: " + request);
// 发送数据
String message = "Hello, Client!";
byte[] sendData = message.getBytes();
InetAddress clientAddress = receivePacket.getAddress();
int clientPort = receivePacket.getPort();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, clientAddress, clientPort);
socket.send(sendPacket);
// 关闭连接
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}