端口通信是指通过指定的端口建立连接并进行数据交换的过程。在Java中可以通过Socket类和ServerSocket类来实现端口通信。

//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("localhost", 8888); //指定端口号
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
out.println("hello");
out.flush();
String response = in.readLine();
System.out.println("response:" + response);
in.close();
out.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
//服务端代码
import java.io.*;
import java.net.*;
public class Server {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(8888); //指定端口号
while (true) {
Socket socket = serverSocket.accept(); //等待连接
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
String request = in.readLine();
System.out.println("request:" + request);
out.println("world");
out.flush();
in.close();
out.close();
socket.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}

URL通信是指通过URL地址访问网络资源的过程。在Java中可以通过URLConnection类来实现URL通信。

import java.io.*;
import java.net.*;
public class URLConnectionDemo {
public static void main(String[] args) {
try {
URL url = new URL("http://www.baidu.com");
URLConnection connection = url.openConnection();
connection.connect();
InputStream inputStream = connection.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = in.readLine()) != null) {
System.out.println(line);
}
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}