在java中寫入對象和字符串的錯誤

Question

我有一個客戶端和服務器，它們之間交換消息和對象。
我的問題是當我在toString和字符串的幫助下發送對象時。如何從字符串中挑選出對象並將該對象添加到列表中; 我寫了代碼。

Server代碼：

import java.net.*; 
import java.util.ArrayList; 
import java.io.*; 

public class Server { 

public static void main(String[] args) { 
    ArrayList <PhoneBook> listPhone=new ArrayList<PhoneBook>(); 

    PhoneBook a = new PhoneBook("a","a","","",1); 
    listPhone.add(a); 
    PhoneBook pB = new PhoneBook(); 
    String ob; 
    try{ 

     ServerSocket server = new ServerSocket(5555,50); 

     System.out.println("Waiting Incoming Connection..."); 
     System.out.println("Local Address :"+server.getInetAddress()+" Port :"+server.getLocalPort()); 
     Socket sock = server.accept(); 

     ObjectOutputStream out =new ObjectOutputStream(sock.getOutputStream()); 
     ObjectInputStream in =new ObjectInputStream(sock.getInputStream()); 

     String strin =(String) in.readObject(); 

     if (strin.equals("START")){ 
     out.writeObject("WAITING"); 
     out.flush();} 
     strin =(String) in.readObject(); 
     String[] str=strin.split("\n"); 
     if(str[0].equals("REQUEST_SEARCH")){ 

       try{ 
        // in this line is error 
        pB = (PhoneBook)in.readObject(); //String cannot be cast to PhoneBook 
        out.flush(); 
     }catch(ClassNotFoundException classnot){ 
      System.err.println("Data received in unknown format");} 
       out.writeObject("RECORSDS"); 
       out.flush(); 
       String sName = pB.getsurName(); 
       for(int i=0;i<listPhone.size();i++) 
       if(listPhone.get(i).getsurName().equals(sName)){ 
       out.writeObject(pB.toString()); 
       out.flush(); 

     }else{ 
     out.writeObject("NXRECORD"); 
     out.flush(); 
     }} 
     strin =(String) in.readObject(); 
     String[] st=strin.split("\n"); 

     if(st[0].equals("REQUEST_INSERT")){ 

      listPhone.add(pB); 
      System.out.println("The contact is add"); 
      out.writeObject("OK"); 
      out.flush(); 
     } 
     out.flush(); 

     if(strin.equals("END")){ //bye = terminate the conversation 

     in.close(); 
     out.close(); 
     sock.close(); 
     System.out.println("Connection Closing...");} 
     } 
     catch (Exception ex){ 
     System.out.println("Error during I/O"); 
     ex.getMessage(); 
     ex.printStackTrace(); 
     } } } 

客戶端代碼：

 if (strin.equals("WAITING")) { 
     System.out.println("The server says: " + strin); 
     // out.writeObject("REQUEST_SEARCH\n"); 
     // out.flush(); 
     System.out.println("The server says: " + strin); 
     System.out.print("Write the contact elements "); 
     System.out.print("Write the name: "); 
     String name = input.nextLine(); 
     System.out.print("Write the surname: "); 
     String surName = input.nextLine(); 
     System.out.print("Write the job: "); 
     String job = input.nextLine(); 
     System.out.print("Write the street: "); 
     String street = input.nextLine(); 
     System.out.print("Write the phone number: "); 
     int number = input.nextInt(); 
     PhoneBook p = new PhoneBook(name, surName, job, street, number); 
     out.writeObject("REQUEST_SEARCH\n" + p.toString()); 
     out.flush(); 
    } 

錯誤：

Connection reset 
at java.net.SocketInputStream.read(Unknown Source) at 
java.net.SocketInputStream.read(Unknown Source)  at 
java.net.SocketInputStream.read(Unknown Source)  at 
java.io.ObjectInputStream$PeekInputStream.peek(Unknown Source) at 
java.io.ObjectInputStream$BlockDataInputStream.peek(Unknown Source) 
    at java.io.ObjectInputStream$BlockDataInputStream.peekByte(Unknown Source) at 
     java.io.ObjectInputStream.readObject0(Unknown Source) at 
     java.io.ObjectInputStream.readObject(Unknown Source)  at Server.main 

應用背景：

該程序與接觸PhooneBook（服務器）和客戶端首先發送一個開始，服務器把它和客戶端後，發信等待做一個對象電話簿，包括姓名，工作，街道和電話併發送它與消息REQUEST_SEARCH服務器拿消息和對象（聯繫人）和搜索數組列表姓氏如果存在聯繫人，如果存在回發對象並顯示姓名，姓氏，工作和其他與toString()和消息RECORDS然後客戶端發送確定和服務器發回END和連接正在關閉如果聯繫人不存在服務器發送混亂年齡NXRECORD客戶端發回一條消息REQUEST_INSERT服務器拿它並在arraylist中添加對象併發送OK並且客戶端發回END並關閉連接。

Answer 1

我不知道你在這條線後發送給服務器。

out.writeObject("REQUEST_SEARCH\n" + p.toString()); 

但我認爲你發送String到服務器。 而在服務器端，同時取回你使用它下面的行鑄字來代替PhoneBook的String：

pB = (PhoneBook)in.readObject(); 

這導致流mismatch..Hence的異常引起的。
此問題的解決方案如下所示：我假設您的PhoneBook類是Serializable。

在客戶端使用：

out.writeObject("REQUEST_SEARCH\n" + p.toString()); 
out.writeObject(p);//Given that PhoneBook is Serializable.