a3mao — Thu, 09 Nov 2006 04:22:00 GMT

转自�Q?/font> http://www.j2medev.com/code/j2se/language/200602/1343.html

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class CardReader {
   public static void main ( String [] args ) {
     Card3 card = new Card3 ( 12 , Card3.SPADES ) ;
     System.out.println ( "Card to write is: " + card ) ;

     try {
       FileOutputStream out = new FileOutputStream ( "card.out" ) ;
       ObjectOutputStream oos = new ObjectOutputStream ( out ) ;
       oos.writeObject ( card ) ;
       oos.flush () ;
     } catch ( Exception e ) {
       System.out.println ( "Problem serializing: " + e ) ;
     }

     Card3 acard = null ;

     try {
       FileInputStream in = new FileInputStream ( "card.out" ) ;
       ObjectInputStream ois = new ObjectInputStream ( in ) ;
       acard = ( Card3 ) ( ois.readObject ()) ;
     } catch ( Exception e ) {
       System.out.println ( "Problem serializing: " + e ) ;
     }

     System.out.println ( "Card read is: " + acard ) ;

   }
}

class Card3 implements Serializable {
   private int suit = UNASSIGNED;

   private int number = UNASSIGNED;

   public final static int UNASSIGNED = - 1 ;

   public final static int DIAMONDS = 1 ;

   public final static int CLUBS = 2 ;

   public final static int HEARTS = 3 ;

   public final static int SPADES = 4 ;

   public final static int ACE = 1 ;

   public final static int KING = 13 ;

   public Card3 ( int number, int suit ) {
     if ( isValidNumber ( number )) {
       this .number = number;
     } else {
       //Error
     }

     if ( isValidSuit ( suit )) {
       this .suit = suit;
     } else {
       //Error
     }
   }

   public int getSuit () {
     return suit;
   }

   public int getNumber () {
     return number;
   }

   public static boolean isValidNumber ( int number ) {
     if ( number >= ACE && number <= KING ) {
       return true ;
     } else {
       return false ;
     }
   }

   public static boolean isValidSuit ( int suit ) {
     if ( suit >= DIAMONDS && suit <= SPADES ) {
       return true ;
     } else {
       return false ;
     }
   }

   public boolean equals ( Object obj ) {
     if ( obj instanceof Card3 ) {
       Card3 card = ( Card3 ) obj;
       if ( card.getNumber () == this .number && card.getSuit () == this .suit ) {
         return true ;
       } else {
         return false ;
       }
     } else {
       return false ;
     }
   }

   public int hashCode () {
     return number * suit;
   }

   public String toString () {
     return numberToString ( this .number ) + " of " + suitToString ( this .suit ) ;
   }

   public static String numberToString ( int number ) {
     String result = "" ;
     switch ( number ) {
     case ACE:
       result = "Ace" ;
       break ;
     case 2 :
       result = "Two" ;
       break ;
     case 3 :
       result = "Three" ;
       break ;
     case 4 :
       result = "Four" ;
       break ;
     case 5 :
       result = "Five" ;
       break ;
     case 6 :
       result = "Six" ;
       break ;
     case 7 :
       result = "Seven" ;
       break ;
     case 8 :
       result = "Eight" ;
       break ;
     case 9 :
       result = "Nine" ;
       break ;
     case 10 :
       result = "Ten" ;
       break ;
     case 11 :
       result = "Jack" ;
       break ;
     case 12 :
       result = "Queen" ;
       break ;
     case KING:
       result = "King" ;
       break ;
     case UNASSIGNED:
       result = "Invalid Number" ;
       break ;
     }
     return result;
   }

   public static String suitToString ( int suit ) {
     String result = "" ;
     switch ( suit ) {
     case DIAMONDS:
       result = "Diamonds" ;
       break ;
     case CLUBS:
       result = "Clubs" ;
       break ;
     case HEARTS:
       result = "Hearts" ;
       break ;
     case SPADES:
       result = "Spades" ;
       break ;
     case UNASSIGNED:
       result = "Invalid Suit" ;
       break ;
     }
     return result;
   }
}

a3mao 2006-11-09 12:22 发表评论

Serializable

a3mao — Thu, 09 Nov 2006 04:12:00 GMT

接口 java.io.Serializable

public interface Serializable

实现 java.io.Serializable 接口的类是可序列化的。没有实现此接口的类��不能��它们的�Q一状态被序列化或逆序列化。序列化�cȝ��所有子�c�L��w�都是可序列化的。这个序列化接口没有��M��Ҏ(gu��)��和域�Q�仅用于标识序列化的语意�?

允许非序列化�cȝ��子类型序列化�Q�子�c�d��可以假定负责保存和恢复父�c�d��的公有的、保护的�?如果可访�?包的域的状态。只要该�c?扩展)有一个无参构造子�Q�可初始化它的状态，那么子类型就可承担上�q�职责。在�q�种情况下申明一个可序列化的�c�L��一个错误。此错误��在�q�行时被��(g��)��?

在逆序列化期间�Q�将使用非序列化�cȝ��公用的或保护的无参构造子对它的域�q�行初始化。可序列化子�c�d��能讉K��父类的无参构造子。它的所有域��从相应��中被恢复�?

当遍历一个图象时�Q�很可能遇到一个不支持序列化接口的对象。此时将抛出 NotSerializableException 异常�Q�且标识该非序列化对象类�?

在序列化处理�q�程中需要特定句柄的�c�，必须使用如下�q�些恰当的标记实现特定的�Ҏ(gu��)��Q?

 private void writeObject(java.io.ObjectOutputStream out)
     throws IOException
 private void readObject(java.io.ObjectInputStream in)
     throws IOException, ClassNotFoundException;

writeObject �Ҏ(gu��)��负责写特定类的对象的状态，以至相应�?readObject �Ҏ(gu��)��能恢复它�?通过调用 out.defaultWriteObject 可激�z�M��存对象域的缺省机制。此�Ҏ(gu��)��不必兛_��(j��)状态是属于它的父类�q�是子类�?使用 writeObject �Ҏ(gu��)��或基本类型支持的 DataOutput �Ҏ(gu��)��每个域的状态保存到 ObjectOutputStream 中�?

readObject �Ҏ(gu��)��负责从此��中��d��q�恢复类的域。它可能调用 in.defaultReadObject �Ҏ(gu��)��来调用该对象的非�?r��n)态和非暂时的域的�~�省恢复机制�?defaultReadObject �Ҏ(gu��)��使用该流中的信息�Q�用当前对象中的已命名域分配保存在流中该对象的相应域。当�c�d��改进增加�?ji��n)新域时�Q�这个接口也做相应处理。此�Ҏ(gu��)��不必兛_��(j��)状态是属于它的父类�q�是子类�?使用 writeObject �Ҏ(gu��)��或基本类型支持的 DataOutput �Ҏ(gu��)��每个域的状态保存到 ObjectOutputStream 中�?/p>

a3mao 2006-11-09 12:12 发表评论

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Serializable

接口 java.io.Serializable