java - java从socket读取数据

Question

所以，我正在尝试从套接字读取数据。我已经建立了一个连接并向正在监听的另一个套接字发送了一条消息，但它似乎没有收到任何内容。客户端代码:

import java.net.*;
import java.io.*;
import java.util.*;
public class TCPClient {
 /*Conecting to server.
 */
 public static void Client(String[] args){
  int port = 47361;
  Scanner in = new Scanner(System.in);
  System.err.print("Starting up...");
  Socket CS1 = null; //Declaring CS1 as a socket
  DataOutputStream DOS1 = null; //Declaring an outputput data stream "DOS1"
  DataInputStream DIS1 = null; //Setting the values to null
  System.err.println("All created.");
  System.out.println("---------");
  System.out.println(" OPTIONS");
  System.out.println("---------");
  System.out.println("0. Connect.");
  System.out.println("1. Change port.");
  System.out.println("2. Cancel start-up.");
  System.out.println("");
  System.out.println("Choose an option.");
  try {
   short ans = in.nextShort();
   if (ans == 2){
    System.err.println("System.exit(0)");
    System.exit(0);
   }
   if (ans == 1){
     System.out.print("Enter the new port: ");
     port = in.nextInt();
     ans = 0;
   }
   if (ans == 0){
    System.out.print("Enter the IP: ");
    CS1 = new Socket(in.next(), port); //Creating an instane of the "CS1" socket
    System.err.print("Request sent on port " + port + ".");
    DOS1 = new DataOutputStream(CS1.getOutputStream());
    DIS1 = new DataInputStream(CS1.getInputStream()); //creating output and input streams
    System.err.println("Instances created!");
    if (DIS1 != null){
     System.err.println("DIS1 is connected!");
    }
    else {
     System.err.println("DIS1 is null!");
    }
    if (DOS1 != null) {
     System.err.println("DOS1 is connected!");
     System.out.print("Enter input: ");
     String FirstMessage = in.nextLine();
     DOS1.writeBytes(FirstMessage);
     String SecondMessage = DIS1.readLine();
     System.out.println(SecondMessage);
     if (SecondMessage.equals(FirstMessage)) {
     }
     else {
      System.out.println("Please check the code, FirstMessage != SecondMessage");
      }
    }
    else {
     System.err.println("DOS1 is null!");
    }
    if (CS1 != null) {
     System.err.println("CS1 is connected!");
    }
    else {
     System.err.println("CS1 is null!");
    }
    DIS1.close();
    DOS1.close();
    CS1.close(); //closing everything
   }
  }
  catch (IOException e){
   System.err.println("IOException: " + e.getMessage());
  }
 }
}

服务器代码:

import java.net.*;
import java.io.*;
import java.util.*;
public class TCPServer {
 /*Connecting to client
  */
 public static void Server (String[] args) {
  System.err.print("Starting up...");
  ServerSocket SS1 = null;
  DataOutputStream DOS1 = null;
  DataInputStream DIS1 = null;//Setting the values to null
  System.err.println("All created.");
  Scanner in = new Scanner(System.in);
  try {
   SS1 = new ServerSocket(47361); //setting the socket SS1 to port 5000 and creating an instance
   System.err.print("Listening on port 47361...");
   Socket CS1 = SS1.accept(); //accepting the connection request
   DOS1 = new DataOutputStream(CS1.getOutputStream());
   DIS1 = new DataInputStream(CS1.getInputStream());//creating output and input streams
   System.err.println("Instances created!");
   if (DIS1 != null){
    System.err.println("DIS1 is connected!");
    System.err.println(DIS1);
   }
   else {
    System.err.println("DIS1 is null!");
   }
   if (DOS1 != null) {
    System.err.println("DOS1 is connected!");
    System.err.println(DOS1);
   }
   else {
    System.err.println("DOS1 is null!");
   }
   if (SS1 != null) {
    System.err.println("SS1 is connected!");
    System.err.println(SS1);
   }
   else {
    System.err.println("SS1 is null!");
   }
   String FirstMessage = null;
   FirstMessage = DIS1.readLine();
   System.out.println(FirstMessage);
   String SecondMessage = FirstMessage;
   DOS1.writeBytes(SecondMessage);
   DIS1.close();
   DOS1.close();
   SS1.close(); //closing everything
  }
  catch (IOException error){
   System.err.println("IOException " + error.getMessage());
  }
catch (java.util.InputMismatchException error2){
   System.err.println("IOException " + error2.getMessage());
  }
 }
}

到目前为止，它几乎是一个 EchoServer，没有 Buffered。我查看了调试器，它卡在服务器中的 FirstMessage = DIS1.readLine(); 行和服务器中的 String SecondMessage = DIS1.readLine(); 上客户。此外，即使我输入了任何可能的输入，服务器和客户端都在等待输入。为什么会发生这种情况？我怎样才能做到这一点？

旁注:我知道 i/o 流或套接字永远不会等于 null。另外，编译器警告我类 java.io.DataInputStream 已被弃用。您建议使用哪些其他类？

另一个旁注:我是 IO 新手，请不要为此杀了我哈哈:)

谢谢!

Answer 1

常见问题。你在读台词，但你没有在写台词。写入时在消息中添加行终止符。