Java 实现端口监听及处理网络请求

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class PortListener {
public static void main(String[] args) throws IOException {
int port = 12345; // 监听的端口号

try (ServerSocket serverSocket = new ServerSocket(port)) {
System.out.println("Listening on port " + port);

while(true) {
Socket clientSocket = serverSocket.accept();

Thread t = new ClientHandler(clientSocket);
t.start();
}
} catch(IOException e){
System.err.println(e.getMessage());
}
}

private static class ClientHandler extends Thread{
private final Socket socket;

public ClientHandler(Socket socket) {
this.socket = socket;
}

@Override
public void run() {
try (
InputStream inputstream = socket.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(inputstream))
) {

String line;
while ((line = reader.readLine()) != null) {
processRequest(line); // 处理从客户端发送过来的每行数据
}

socket.close();

} catch (IOException ex) {
System.out.println("Error handling client request");
}
}

private void processRequest(String messageFromClient) {
// 在这里对接收的消息内容做出响应或者进一步解析后操作数据库等...
System.out.printf("[Received]: %s%n", messageFromClient);

// 假设我们只是简单地返回同样的消息给客户端：
sendMessageBack(messageFromClient);
}

private void sendMessageBack(String responseMessage) {
OutputStream outputStream = null;
PrintWriter writer = null;

try {
if(socket.isConnected()){
outputStream = socket.getOutputStream();
writer = new PrintWriter(outputStream, true);

writer.write(responseMessage);
writer.flush();
}

}catch(Exception e){
throw new RuntimeException("Failed to send back the response.", e);
} finally {
closeResource(writer);
closeResource(outputStream);
}
}

private void closeResource(Closeable resource) {
if(resource!=null){
try{resource.close();}
catch(IOException ignore){}
}
}
}
}