Java/File Input Output/ObjectInputStream
Содержание
- 1 Create ObjectInputStream out of FileInputStream
- 2 new ObjectInputStream(new BufferedInputStream(new FileInputStream(StringFileName)));
- 3 ObjectInputStream, ObjectOutputStream and java.io.Serializable
- 4 Object serialization with Serializable interface, ObjectOutputStream and ObjectInputStream.
- 5 Read different data types from ObjectInputStream
- 6 Reading objects from file using ObjectInputStream
- 7 Store objects in file
- 8 Use ObjectOutputStream and ObjectInputStream to write and read Hashtable
Create ObjectInputStream out of FileInputStream
/*
* 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;
}
}
new ObjectInputStream(new BufferedInputStream(new FileInputStream(StringFileName)));
/*
* 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();
}
}
}
ObjectInputStream, ObjectOutputStream and java.io.Serializable
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());
}
}
Object serialization with Serializable interface, ObjectOutputStream and ObjectInputStream.
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();
}
}
Read different data types from ObjectInputStream
/*
* 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();
}
}
}
Reading objects from file using ObjectInputStream
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();
}
}
Store objects in file
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 + "]";
}
}
Use ObjectOutputStream and ObjectInputStream to write and read Hashtable
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( ));
}
}
