java常见面试题：如何使用Java进行网络编程？

Java中进行网络编程主要涉及到使用Java的Socket和ServerSocket类。以下是一个简单的TCP客户端和服务器的例子：

TCP服务器

java复制代码

	import java.io.*;
	import java.net.*;
	public class TCPServer {
	public static void main(String[] args) throws IOException {
	int port = 8000;
	try (
	ServerSocket serverSocket = new ServerSocket(port);
	Socket clientSocket = serverSocket.accept(); // accept the client connection
	PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);
	BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
	) {
	String inputLine;
	while ((inputLine = in.readLine()) != null) { // read from the client
	out.println(inputLine); // send back the data to the client
	}
	} catch (IOException e) {
	e.printStackTrace();
	}
	}
	}

TCP客户端

java复制代码

	import java.io.*;
	import java.net.*;
	public class TCPClient {
	public static void main(String[] args) throws IOException {
	String hostName = "localhost"; // or 127.0.0.1 for IPv4 loopback address
	int port = 8000;
	try (
	Socket echoSocket = new Socket(hostName, port);
	PrintWriter out = new PrintWriter(echoSocket.getOutputStream(), true);
	BufferedReader in = new BufferedReader(new InputStreamReader(echoSocket.getInputStream()));
	BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))
	) {
	String userInput;
	while ((userInput = stdIn.readLine()) != null) { // read from stdin and send to the server
	out.println(userInput); // send the data to the server
	System.out.println("Echo from the server: " + in.readLine()); // read from the server and display on console
	}
	} catch (UnknownHostException e) {
	System.err.println("Don't know about host " + hostName);
	System.exit(1);
	} catch (IOException e) {
	System.err.println("Couldn't get I/O for the connection to " + hostName);
	System.exit(1);
	}
	}
	}

以上是一个简单的回声服务器和客户端的例子，服务器接收客户端发送的消息，然后将其原样返回。这只是网络编程的冰山一角，实际应用中可能需要处理更复杂的情况，例如并发连接、错误处理、数据加密等。