套接字服务器客户端不显示输出

Question

我正在用java做一个服务器套接字项目，客户端应该向服务器发送消息，服务器读取消息，然后将其转换为大写，但我不确定为什么我没有得到输出，最终是temp，它没有被转换，它是一个套接字tcp/ip程序，这是我的客户端程序：

import java.io.*;
import java.net.*;
import java.util.Scanner;
class SocketClient {
public static void main(String argv[]) {
int port = 1234;
try {
Scanner s1=new Scanner(System.in);
Socket s=new Socket("localhost",port);
Scanner sc=new Scanner(s.getInputStream());
System.out.println("Enter a word to convert :");
String m=s1.nextLine();
PrintStream p=new PrintStream(s.getOutputStream());
p.println(m);
String temp=sc.nextLine();
System.out.println("the converted word is :"+temp.toUpperCase());

} catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}}}

我的服务器程序是：

import java.io.*;
import java.net.*;
import java.util.Scanner;
public class SocketServeur {
public static void main(String argv[]) {
int port = 1234;
try {
ServerSocket ss= new ServerSocket(port);
Socket so=ss.accept();
Scanner s1=new Scanner(so.getInputStream());
String m=s1.nextLine();
String temp=m;
PrintStream p=new PrintStream(so.getOutputStream());

p.println(temp);

} catch (Exception e) {
System.err.println("Error : " + e);
}
}

}

Answer 1

我把你的例子搞砸了一点。服务器将并且可以同时处理多个客户端。对于高级策略，您可以将服务器和客户端放在它们自己的文件中，授予高级可控性并限制对变量的访问。此外，请阅读源代码中的注释。

在客户端之前启动服务器是很重要的；否则会出现连接错误。

package stackoverflow.socketprinters;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
public class SocketServeur {
static public final int SERVER_PORT = 1234;

public static void main(final String argv[]) {
final int port = SERVER_PORT;
System.out.println("Creating socket on port " + port + "...");
try (final ServerSocket serverSocket = new ServerSocket(SERVER_PORT);) {
while (!serverSocket.isClosed()) {
System.out.println("Server waiting for connection...");
@SuppressWarnings("resource") final Socket socket = serverSocket.accept(); // will be closed in handleClient()
startClientHandler(socket); // you could also use Executors.newFixedThreadPool(amount), see https://www.baeldung.com/thread-pool-java-and-guava
}
} catch (final Exception e) {
System.err.println("Error : " + e);
}
}
private static void startClientHandler(final Socket pSocket) {
System.out.println("tStarting handler for " + pSocket.getRemoteSocketAddress() + "...");
final String threadName = "handleClient(" + pSocket.getRemoteSocketAddress() + ")";
final Thread socketThread = new Thread(() -> handleClient(pSocket), threadName);
socketThread.setDaemon(false); // Thread will die and release resources when ServerSocket gets closed.
socketThread.start();
}
private static void handleClient(final Socket pSocket) { // only using a method here, usually client handling is done in its own class
System.out.println("tHandling request for " + pSocket.getRemoteSocketAddress() + "...");
try (final Scanner socketScanner = new Scanner(pSocket.getInputStream());
final PrintStream socketPrintstream = new PrintStream(pSocket.getOutputStream());) {
final String readMessage = socketScanner.nextLine();
final String processedMessage = readMessage.toUpperCase();
socketPrintstream.println(processedMessage);
} catch (final Exception e) {
System.err.println("Error : " + e);
} finally {
try {
pSocket.close();
} catch (final Exception e2) { /* ignore */ }
System.out.println("tRequest handled for " + pSocket.getRemoteSocketAddress());
}
}
}

和

package stackoverflow.socketprinters;
import java.io.PrintStream;
import java.net.Socket;
import java.util.Scanner;
class SocketClient {
public static void main(final String argv[]) {
try (final Scanner sysinScanner = new Scanner(System.in);
final Socket socket = new Socket("localhost", SocketServeur.SERVER_PORT);
final Scanner socketScanner = new Scanner(socket.getInputStream());
final PrintStream socketPrintstream = new PrintStream(socket.getOutputStream());) {
System.out.print("Enter a word to convert: ");
final String message = sysinScanner.nextLine();
socketPrintstream.println(message);
System.out.println("Converting...");
final String receivedMessage = socketScanner.nextLine();
System.out.println("the converted word is: '" + receivedMessage + "'");
} catch (final Exception e) {
e.printStackTrace();
}
System.out.println("Client closing now...");
}
}

这将为服务器创建输出：

Creating socket on port 1234...
Server waiting for connection...  
Starting handler for /127.0.0.1:49970...  
Server waiting for connection...  
Handling request for /127.0.0.1:49970...  
Request handled for /127.0.0.1:49970  
Starting handler for /127.0.0.1:49977...  
Server waiting for connection...  
Handling request for /127.0.0.1:49977...  
Request handled for /127.0.0.1:49977  

对于客户来说：

Enter a word to convert: dasdsadas
Converting...
the converted word is: 'DASDSADAS'
Client closing now...

如果在这一点上，您的客户端仍然没有给您预期的输出，那么您就存在一些编译问题。在这种情况下，请检查编译器输出。