Cara menggunakan serialization in php javatpoint

Serialisasi object adalah sebuah proses mengubah object menjadi byte stream yang di representasikan dalam sebuah string. Proses serialisasi object digunakan untuk menyimpan suatu object kedalam file atau memori dalam komputer atau untuk keperluan transmisi object. Kebalikan dari proses serialisasi adalah proses deserialisasi.

Untuk melakukan proses serialisasi dalam PHP digunakan fungsi serialize() dan untuk melakukan proses deserialisasi digunakan fungsi unserialize(). Fungsi serialize mengembalikan nilai string yang berisi representasi dari nilai sebuah object yang dapat disimpan dalam PHP. Sedangkan fungsi unserialize() digunakan untuk membuat ulang object dari string yang dibuat oleh fungsi serialize().

Fungsi serialize() hanya menyimpan object beserta nilai dari variabel object saat dijalankan. Fungsi serialize() tidak menyimpan method hanya nama class.

Berikut ini contoh program menggunakan serialize() dan unserialize()

1. Buat sebuah sebuah class dengan nama A berikut ini, lalu simpan dalam file “classa.inc”

 <?php  
  class A {  
    public $text;  
     
    public function tampilkan() {  
      echo $this->text;  
    }  
      
    public function __construct ($x) {  
                $this->text = $x;  
       }   
  }  
 ?>  

Pada class A terdapat sebuah properti $text dan sebuah method tampilkan() serta sebuah constructor untuk menentuan nilai properti $text saat instantisasi class kedalam object.

2. Buat sebuah program untuk men-serialisasi object lalu simpan dengan nama page1.php

 <?php  
 if (isset($_POST['Enter']))  
 {  
  if(!empty($_POST['text']))  
  {  
       include("classa.inc");  
         
       $a = new A($_POST['text']);  
       $s = serialize($a);  

       // menyimpan variabel $s disuatu tempat yang bisa ditemukan oleh page2.php  
       if(file_put_contents('store', $s))  
       {  
            echo "Proses Serialisasi Berhasil, Silahkan buka <a href='page2.php'>Page 2</a> Untuk melihatnya";  
       }  
  }  
  else echo "Teks belum diisi, proses serialisasi dibatalkan!.<br/><a href='page1.php'>Reload page</a>";  
 }  
 else  
 echo '  
  <h1>Masukkan text untuk menguji proses serialisasi</h1>  
  <form action="" method="POST">  
  <input type="text" name="text"><br/>  
  <input type="submit" name ="Enter" value="Enter">&nbsp;<i>Klik Untuk Serialize Object dari Class A</i>  
  </form>  
 ';  
 ?>  
 

Pada program diatas kita membuat sebuah form dengan input text untuk memasukkan nilai dan sebuah tombol submit unruk mengeksekusi proses serialisasi object.

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Ada tiga tampilan pada program ini, yaitu saat kondisi awal akan tampil form input lalu saat dijalankan form akan disembunyikan dan sebagai gantinya akan tampil pesan bahwa proses serialisasi berhasil. Yang ketiga jika teks kosong pesan akan berubah menjadi peringatan bahwa teks kosong dan proses serialisasi dibatalkan.

JIka proses serialisasi berhasil kita bisa membuka file page2.php melalui link untuk melihat hasil serialisasi melalui proses unserialize.

3. Buat sebuah program untuk men-unserialize lalu simpan dengan nama page2.php

 <?php  
  // dibutuhkan untuk proses deserialisasi object  
  include("classa.inc");  
   
  $s = file_get_contents('store');  
  $a = unserialize($s);  
   
  // menampilkan data dengan method tampilkan()   
  echo "Data yang disimpan pada proses serialisasi dari Page 1 adalah :<br/>";  
  echo "<h1> ";  
  echo $a->tampilkan();  
  echo "</h1><br/>";  
  echo "<a href='page1.php'>Kembali ke Page 1</a>";  
   
 ?>  

pada program diatas kita mengambil hasil proses serialisasi dari file page1.php dengan fungsi unserialize() lalu menginstantisasi menjadi object dan menampilkan nilainya dengan method tampilkan().

Java provides a mechanism, called object serialization where an object can be represented as a sequence of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object.

After a serialized object has been written into a file, it can be read from the file and deserialized that is, the type information and bytes that represent the object and its data can be used to recreate the object in memory.

Most impressive is that the entire process is JVM independent, meaning an object can be serialized on one platform and deserialized on an entirely different platform.

Classes ObjectInputStream and ObjectOutputStream are high-level streams that contain the methods for serializing and deserializing an object.

The ObjectOutputStream class contains many write methods for writing various data types, but one method in particular stands out −

public final void writeObject(Object x) throws IOException

The above method serializes an Object and sends it to the output stream. Similarly, the ObjectInputStream class contains the following method for deserializing an object −

public final Object readObject() throws IOException, ClassNotFoundException

This method retrieves the next Object out of the stream and deserializes it. The return value is Object, so you will need to cast it to its appropriate data type.

To demonstrate how serialization works in Java, I am going to use the Employee class that we discussed early on in the book. Suppose that we have the following Employee class, which implements the Serializable interface −

Example

public class Employee implements java.io.Serializable {
   public String name;
   public String address;
   public transient int SSN;
   public int number;
   
   public void mailCheck() {
      System.out.println("Mailing a check to " + name + " " + address);
   }
}

Notice that for a class to be serialized successfully, two conditions must be met −

• The class must implement the java.io.Serializable interface.

• All of the fields in the class must be serializable. If a field is not serializable, it must be marked transient.

If you are curious to know if a Java Standard Class is serializable or not, check the documentation for the class. The test is simple: If the class implements java.io.Serializable, then it is serializable; otherwise, it's not.

Serializing an Object

The ObjectOutputStream class is used to serialize an Object. The following SerializeDemo program instantiates an Employee object and serializes it to a file.

When the program is done executing, a file named employee.ser is created. The program does not generate any output, but study the code and try to determine what the program is doing.

Note − When serializing an object to a file, the standard convention in Java is to give the file a .ser extension.

Example

import java.io.*;
public class SerializeDemo {

   public static void main(String [] args) {
      Employee e = new Employee();
      e.name = "Reyan Ali";
      e.address = "Phokka Kuan, Ambehta Peer";
      e.SSN = 11122333;
      e.number = 101;
      
      try {
         FileOutputStream fileOut =
         new FileOutputStream("/tmp/employee.ser");
         ObjectOutputStream out = new ObjectOutputStream(fileOut);
         out.writeObject(e);
         out.close();
         fileOut.close();
         System.out.printf("Serialized data is saved in /tmp/employee.ser");
      } catch (IOException i) {
         i.printStackTrace();
      }
   }
}

Deserializing an Object

The following DeserializeDemo program deserializes the Employee object created in the SerializeDemo program. Study the program and try to determine its output −

Example

import java.io.*;
public class DeserializeDemo {

   public static void main(String [] args) {
      Employee e = null;
      try {
         FileInputStream fileIn = new FileInputStream("/tmp/employee.ser");
         ObjectInputStream in = new ObjectInputStream(fileIn);
         e = (Employee) in.readObject();
         in.close();
         fileIn.close();
      } catch (IOException i) {
         i.printStackTrace();
         return;
      } catch (ClassNotFoundException c) {
         System.out.println("Employee class not found");
         c.printStackTrace();
         return;
      }
      
      System.out.println("Deserialized Employee...");
      System.out.println("Name: " + e.name);
      System.out.println("Address: " + e.address);
      System.out.println("SSN: " + e.SSN);
      System.out.println("Number: " + e.number);
   }
}

This will produce the following result −

Output

Deserialized Employee...
Name: Reyan Ali
Address:Phokka Kuan, Ambehta Peer
SSN: 0
Number:101

Here are following important points to be noted −

• The try/catch block tries to catch a ClassNotFoundException, which is declared by the readObject() method. For a JVM to be able to deserialize an object, it must be able to find the bytecode for the class. If the JVM can't find a class during the deserialization of an object, it throws a ClassNotFoundException.

• Notice that the return value of readObject() is cast to an Employee reference.

• The value of the SSN field was 11122333 when the object was serialized, but because the field is transient, this value was not sent to the output stream. The SSN field of the deserialized Employee object is 0.