我正在构建我的第一个 telnet 服务器。我可以连接到它，但由于某种原因，它在第一次连接时自动在菜单上失败。连接后，它会立即显示欢迎消息，然后立即指出我的第一个输入不是一个可行的选择，然后再试一次。然后它可以让我正确地做出下一个选择。
如何防止java看到任何初始输入并等到用户实际按下一个键开始接受用户的输入？
我的代码——
public class Sample_server {
private static int port=4444, maxConnections=5;
// Listen for incoming connections and handle them
public static void main(String[] args) {
int i=0;
try{
ServerSocket listener = new ServerSocket(port);
Socket server;
while((i++ < maxConnections) || (maxConnections == 0)){
doComms connection;
server = listener.accept();
doComms conn_c= new doComms(server);
Thread t = new Thread(conn_c);
t.start();
}
} catch (IOException ioe) {
System.out.println("IOException on socket listen: " + ioe);
ioe.printStackTrace();
}
}
}
class doComms implements Runnable {
private Socket server;
private String line,input;
doComms(Socket server) {
this.server=server;
}
public void run () {
//input="";
try {
// Get input from the client
DataInputStream in = new DataInputStream (server.getInputStream());
PrintStream out = new PrintStream(server.getOutputStream());
out.println("You have connected to the server.");
out.println("Welcome.");
try {
MenuSystemClass newMenu = new MenuSystemClass();
newMenu.MainMenu(in, out);
} catch (Exception e) {
System.out.println("Failed to start the menu");
}
// Now write to the client
System.out.println("Overall message is:" + input);
server.close();
} catch (IOException ioe) {
System.out.println("IOException on socket listen: " + ioe);
ioe.printStackTrace();
}
}
}
我的菜单代码
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package sample_server;
import java.io.DataInputStream;
import java.io.PrintStream;
import java.util.Scanner;
/**
* My Custom Menu Class
* @author aaron
*/
public class MenuSystemClass {
public void MainMenu(DataInputStream in, PrintStream out) {
// Set Run Boolean to true
boolean running = true;
// We switch the input to lowecase here and compare
while(running) {
out.println("A: New Char ; V: View ; W: Start Game; S: Save ; D: Delete ; Q: Quit");
// Initialize the scanner
Scanner user_input = new Scanner(in);
// Get the user input
String decision = user_input.next();
// Conver their decision to lowercase and compare to choices.
switch (decision.toLowerCase()) {
case "a":
out.println("This is not yet implemented.");
break;
case "s":
out.println("This is not yet implemented.");
break;
case "d":
out.println("This is not yet implemented.");
break;
case "v":
out.println("This is not yet implemented.");
break;
case "w":
out.println("This is not yet implemented.");
break;
case "q":
return;
default:
out.println("You did not select a viable option.");
out.println("Try again.");
break;
}
}
}
}
我这辈子都无法忽略初始通信正在发生的事情，而只是等到用户真正有目的地输入一些输入。