Java/File Input Output/ObjectInputStream

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Create ObjectInputStream out of FileInputStream

   <source lang="java">

/* 

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
*   - Neither the name of Sun Microsystems nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

import java.io.FileInputStream; import java.io.ObjectInputStream; import java.io.Serializable; public class CardReader { 

 public static void main(String[] args) {
   Card3 card = null;
   try {
     FileInputStream in = new FileInputStream("card.out");
     ObjectInputStream ois = new ObjectInputStream(in);
     card = (Card3) (ois.readObject());
   } catch (Exception e) {
     System.out.println("Problem serializing: " + e);
   }
   System.out.println("Card read is: " + card);
 }

} /* 

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved.
* 
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*  - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*  - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*  - Neither the name of Sun Microsystems nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
* 
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

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;
 }

} 

 </source>



new ObjectInputStream(new BufferedInputStream(new FileInputStream(StringFileName)));

   <source lang="java">

/* 

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
*   - Neither the name of Sun Microsystems nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.EOFException; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.math.BigDecimal; import java.util.Calendar; public class ObjectStreams { 

 static final String dataFile = "invoicedata";
 static final BigDecimal[] prices = { new BigDecimal("19.99"),
     new BigDecimal("9.99"), new BigDecimal("15.99"), new BigDecimal("3.99"),
     new BigDecimal("4.99") };
 static final int[] units = { 12, 8, 13, 29, 50 };
 static final String[] descs = { "Java T-shirt", "Java Mug",
     "Duke Juggling Dolls", "Java Pin", "Java Key Chain" };
 public static void main(String[] args) throws IOException,
     ClassNotFoundException {
   ObjectOutputStream out = null;
   try {
     out = new ObjectOutputStream(new BufferedOutputStream(
         new FileOutputStream(dataFile)));
     out.writeObject(Calendar.getInstance());
     for (int i = 0; i < prices.length; i++) {
       out.writeObject(prices[i]);
       out.writeInt(units[i]);
       out.writeUTF(descs[i]);
     }
   } finally {
     out.close();
   }
   ObjectInputStream in = null;
   try {
     in = new ObjectInputStream(new BufferedInputStream(new FileInputStream(
         dataFile)));
     Calendar date = null;
     BigDecimal price;
     int unit;
     String desc;
     BigDecimal total = new BigDecimal(0);
     date = (Calendar) in.readObject();
     System.out.format("On %tA, %<tB %<te, %<tY:%n", date);
     try {
       while (true) {
         price = (BigDecimal) in.readObject();
         unit = in.readInt();
         desc = in.readUTF();
         System.out.format("You ordered %d units of %s at $%.2f%n", unit,
             desc, price);
         total = total.add(price.multiply(new BigDecimal(unit)));
       }
     } catch (EOFException e) {
     }
     System.out.format("For a TOTAL of: $%.2f%n", total);
   } finally {
     in.close();
   }
 }

} 

 </source>



ObjectInputStream, ObjectOutputStream and java.io.Serializable

   <source lang="java">

import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; class Engine implements Serializable { 

 private int numCylinders;
 Engine(int numCylinders) {
   this.numCylinders = numCylinders;
 }
 int getNumCylinders() {
   return numCylinders;
 }

} class Car implements Serializable { 

 private int numTires;
 private Engine e;
 private String name;
 Car(String name, int numTires, Engine e) {
   this.name = name;
   this.numTires = numTires;
   this.e = e;
 }
 int getNumTires() {
   return numTires;
 }
 Engine getEngine() {
   return e;
 }
 String getName() {
   return name;
 }

} class Main { 

 public static void main(String[] args) throws Exception {
   Car c1 = new Car("Some car", 4, new Engine(6));
   ObjectOutputStream oos = null;
   FileOutputStream fos = new FileOutputStream("car.ser");
   oos = new ObjectOutputStream(fos);
   oos.writeObject(c1);
   ObjectInputStream ois = null;
   FileInputStream fis = new FileInputStream("car.ser");
   ois = new ObjectInputStream(fis);
   Car c2 = (Car) ois.readObject();
   System.out.println("Number of tires = " + c2.getNumTires());
   System.out.println("Number of cylinders = " + c2.getEngine().getNumCylinders());
   System.out.println("Name = " + c2.getName());
 }

} 

 </source>



Object serialization with Serializable interface, ObjectOutputStream and ObjectInputStream.

   <source lang="java">

import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; class MyClass implements Serializable { 

 String str;
 double[] vals;
 File fn;
 public MyClass(String s, double[] nums, String fname) {
   str = s;
   vals = nums;
   fn = new File(fname);
 }
 public String toString() {
   String data = "  str: " + str + "\n  vals: ";
   for (double d : vals)
     data += d + " ";
   data += "\n  fn: " + fn.getName();
   return data;
 }

} public class Main { 

 public static void main(String[] argv) throws Exception {
   double v[] = { 1.1, 2.2, 3.3 };
   double v2[] = { 9.0, 8.0, 7.7 };
   MyClass obj1 = new MyClass("This is a test", v, "Test.txt");
   MyClass obj2 = new MyClass("Alpha Beta Gamma", v2, "Sample.dat");
   ObjectOutputStream fout = new ObjectOutputStream(new FileOutputStream("obj.dat"));
   System.out.println("obj1:\n" + obj1);
   fout.writeObject(obj1);
   System.out.println("obj2:\n" + obj2);
   fout.writeObject(obj2);
   fout.close();
   ObjectInputStream fin = new ObjectInputStream(new FileInputStream("obj.dat"));
   MyClass inputObj;
   inputObj = (MyClass) fin.readObject();
   System.out.println("First object:\n" + inputObj);
   inputObj = (MyClass) fin.readObject();
   System.out.println("Second object:\n" + inputObj);
   fin.close();
 }

} 

 </source>



Read different data types from ObjectInputStream

   <source lang="java">

/* 

* Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
*   - Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*
*   - Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*
*   - Neither the name of Sun Microsystems nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.EOFException; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.math.BigDecimal; import java.util.Calendar; public class ObjectStreams { 

 static final String dataFile = "invoicedata";
 static final BigDecimal[] prices = { new BigDecimal("19.99"),
     new BigDecimal("9.99"), new BigDecimal("15.99"), new BigDecimal("3.99"),
     new BigDecimal("4.99") };
 static final int[] units = { 12, 8, 13, 29, 50 };
 static final String[] descs = { "Java T-shirt", "Java Mug",
     "Duke Juggling Dolls", "Java Pin", "Java Key Chain" };
 public static void main(String[] args) throws IOException,
     ClassNotFoundException {
   ObjectOutputStream out = null;
   try {
     out = new ObjectOutputStream(new BufferedOutputStream(
         new FileOutputStream(dataFile)));
     out.writeObject(Calendar.getInstance());
     for (int i = 0; i < prices.length; i++) {
       out.writeObject(prices[i]);
       out.writeInt(units[i]);
       out.writeUTF(descs[i]);
     }
   } finally {
     out.close();
   }
   ObjectInputStream in = null;
   try {
     in = new ObjectInputStream(new BufferedInputStream(new FileInputStream(
         dataFile)));
     Calendar date = null;
     BigDecimal price;
     int unit;
     String desc;
     BigDecimal total = new BigDecimal(0);
     date = (Calendar) in.readObject();
     System.out.format("On %tA, %<tB %<te, %<tY:%n", date);
     try {
       while (true) {
         price = (BigDecimal) in.readObject();
         unit = in.readInt();
         desc = in.readUTF();
         System.out.format("You ordered %d units of %s at $%.2f%n", unit,
             desc, price);
         total = total.add(price.multiply(new BigDecimal(unit)));
       }
     } catch (EOFException e) {
     }
     System.out.format("For a TOTAL of: $%.2f%n", total);
   } finally {
     in.close();
   }
 }

} 

 </source>



Reading objects from file using ObjectInputStream

   <source lang="java">

import java.io.FileInputStream; import java.io.ObjectInputStream; import java.io.Serializable; public class Main { 

 public static void main(String[] args) throws Exception {
   ObjectInputStream inputStream = new ObjectInputStream(new FileInputStream("yourFile.dat"));
   Object obj = null;
   while ((obj = inputStream.readObject()) != null) {
     if (obj instanceof Person) {
       System.out.println(((Person) obj).toString());
     }
   }
   inputStream.close();
 }

} class Person implements Serializable { 

 private String firstName;
 private String lastName;
 private int age;
 public Person() {
 }
 public String getFirstName() {
   return firstName;
 }
 public void setFirstName(String firstName) {
   this.firstName = firstName;
 }
 public String getLastName() {
   return lastName;
 }
 public void setLastName(String lastName) {
   this.lastName = lastName;
 }
 public int getAge() {
   return age;
 }
 public void setAge(int age) {
   this.age = age;
 }
 public String toString() {
   StringBuffer buffer = new StringBuffer();
   buffer.append(firstName);
   buffer.append("\n");
   buffer.append(lastName);
   buffer.append("\n");
   buffer.append(age);
   buffer.append("\n");
   return buffer.toString();
 }

} 

 </source>



Store objects in file

   <source lang="java">

import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; import java.io.Serializable; public class Main { 

 public static void main(String[] args) throws Exception {
   FileOutputStream fos = new FileOutputStream("books.dat");
   ObjectOutputStream oos = new ObjectOutputStream(fos);
   Book book = new Book("1", "Java", "A");
   oos.writeObject(book);
   oos.flush();
   oos.close();
   FileInputStream fis = new FileInputStream("books.dat");
   ObjectInputStream ois = new ObjectInputStream(fis);
   book = (Book) ois.readObject();
   System.out.println(book.toString());
   ois.close();
 }

} class Book implements Serializable { 

 private String isbn;
 private String title;
 private String author;
 public Book(String isbn, String title, String author) {
   this.isbn = isbn;
   this.title = title;
   this.author = author;
 }
 public String toString() {
   return "[Book: " + isbn + ", " + title + ", " + author + "]";
 }

} 

 </source>



Use ObjectOutputStream and ObjectInputStream to write and read Hashtable

   <source lang="java">

import java.io.FileOutputStream; import java.io.ObjectOutputStream; import java.util.Hashtable; public class Main { 

 public static void main(String[] args) throws Exception {
   Hashtable h = new Hashtable();
   h.put("string", "AAA");
   h.put("int", new Integer(26));
   h.put("double", new Double(Math.PI));
   FileOutputStream fileOut = new FileOutputStream("hashtable.ser");
   ObjectOutputStream out = new ObjectOutputStream(fileOut);
   out.writeObject(h);
     
   FileInputStream fileIn = new FileInputStream("h.ser");
   ObjectInputStream in = new ObjectInputStream(fileIn);
   Hashtable h = (Hashtable)in.readObject(  );
   System.out.println(h.toString(  ));      
 }

} 

 </source>
Источник — «http://www.jexp.ru/index.php?title=Java/File_Input_Output/ObjectInputStream&oldid=6115»