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2010-06-01T05:19:09Z

1 версия

в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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== Create ObjectInputStream from FileInputStream ==



<source lang="java">
import java.io.FileInputStream;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Date;
public class ObjectReader {
public static void main(String[] arguments) {
try {
FileInputStream fi = new FileInputStream("message.obj");
ObjectInputStream oi = new ObjectInputStream(fi);
Message mess = (Message) oi.readObject();
System.out.println("Message:\n");
System.out.println("From: " + mess.from);
System.out.println("To: " + mess.to);
System.out.println("Date: " + mess.when + "\n");
for (int i = 0; i < mess.lineCount; i++)
System.out.println(mess.text[i]);
oi.close();
} catch (Exception e) {
System.out.println("Error " + e.toString());
}
}
}
class Message implements Serializable {
int lineCount;
String from, to;
Date when;
String[] text;
void writeMessage(String inFrom, String inTo, Date inWhen, String[] inText) {
text = new String[inText.length];
for (int i = 0; i < inText.length; i++)
text[i] = inText[i];
lineCount = inText.length;
to = inTo;
from = inFrom;
when = inWhen;
}
}</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>



== 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>

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Admin: 1 версия

в 17:44, 31 мая 2010