序列化是通过将对象转换为字节码来保存对象的特定状态的过程。转换后的字节码用于在2个JVM之间传输对象状态，接收JVM在其中反序列化字节码以检索共享对象的状态。 序列化和反序列化是使用serialVersionUID作为相关jvm中的引用来完成的。

在Java中，使用Serialization和Externalisation接口也可以实现同样的功能

将文件返回为Object: http://www.tutorialspoint.com/java/java_serialization.htm

        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();
              }
           }
        }

    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);
        }
    }

序列化是将Java对象转换为字节数组，然后再将其转换为保留状态的对象的过程。适用于通过网络发送对象或将内容缓存到磁盘等各种事情。

请阅读这篇简短的文章，它很好地解释了编程过程的一部分，然后转到Serializable javadoc。你也可能对这个相关的问题感兴趣。

序列化是将一个对象的状态转换为比特的过程，这样它就可以存储在硬盘上。当您反序列化同一对象时，它将在以后保留其状态。它允许您重新创建对象，而无需手动保存对象的属性。

http://en.wikipedia.org/wiki/Serialization

Java对象序列化

序列化是一种将Java对象图转换为用于存储(到磁盘文件)或传输(通过网络)的字节数组的机制，然后通过使用反序列化，我们可以恢复对象图。 使用引用共享机制正确地恢复对象的图。但是在存储之前，请检查input-file/network中的serialVersionUID和.class文件中的serialVersionUID是否相同。如果不是，则抛出java.io.InvalidClassException。

每个版本化的类必须确定它能够为其写入流和从中读取流的原始类版本。例如，一个有版本控制的类必须声明: serialVersionUID的语法 // ANY-ACCESS-MODIFIER static final long serialVersionUID = (64-bit has)L; private static final long serialVersionUID = 3487495895819393L;

serialVersionUID是序列化过程所必需的。但是开发人员可以选择将其添加到java源文件中。如果没有包含serialVersionUID，序列化运行时将生成serialVersionUID并将其与类关联。序列化对象将包含这个serialVersionUID以及其他数据。

注意——强烈建议所有可序列化类显式声明serialVersionUID，因为默认的serialVersionUID计算对类细节非常敏感，这些细节可能会根据编译器实现的不同而不同，因此可能会在反序列化期间导致意外的serialVersionUID冲突，导致反序列化失败。

检查可序列化类

Java对象只能序列化。如果一个类或它的任何超类实现了java.io.Serializable接口 或其子接口java.io.Externalizable。

A class must implement java.io.Serializable interface in order to serialize its object successfully. Serializable is a marker interface and used to inform the compiler that the class implementing it has to be added serializable behavior. Here Java Virtual Machine (JVM) is responsible for its automatic serialization. transient Keyword: java.io.Serializable interface While serializing an object, if we don't want certain data members of the object to be serialized we can use the transient modifier. The transient keyword will prevent that data member from being serialized. Fields declared as transient or static are ignored by the serialization process. TRANSIENT & VOLATILE +--------------+--------+-------------------------------------+ | Flag Name | Value | Interpretation | +--------------+--------+-------------------------------------+ | ACC_VOLATILE | 0x0040 | Declared volatile; cannot be cached.| +--------------+--------+-------------------------------------+ |ACC_TRANSIENT | 0x0080 | Declared transient; not written or | | | | read by a persistent object manager.| +--------------+--------+-------------------------------------+ class Employee implements Serializable { private static final long serialVersionUID = 2L; static int id; int eno; String name; transient String password; // Using transient keyword means its not going to be Serialized. } Implementing the Externalizable interface allows the object to assume complete control over the contents and format of the object's serialized form. The methods of the Externalizable interface, writeExternal and readExternal, are called to save and restore the objects state. When implemented by a class they can write and read their own state using all of the methods of ObjectOutput and ObjectInput. It is the responsibility of the objects to handle any versioning that occurs. class Emp implements Externalizable { int eno; String name; transient String password; // No use of transient, we need to take care of write and read. @Override public void writeExternal(ObjectOutput out) throws IOException { out.writeInt(eno); out.writeUTF(name); //out.writeUTF(password); } @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException { this.eno = in.readInt(); this.name = in.readUTF(); //this.password = in.readUTF(); // java.io.EOFException } } Only objects that support the java.io.Serializable or java.io.Externalizable interface can be written to/read from streams. The class of each serializable object is encoded including the class name and signature of the class, the values of the object's fields and arrays, and the closure of any other objects referenced from the initial objects.

文件的序列化示例

public class SerializationDemo {
    static String fileName = "D:/serializable_file.ser";

    public static void main(String[] args) throws IOException, ClassNotFoundException, InstantiationException, IllegalAccessException {
        Employee emp = new Employee( );
        Employee.id = 1; // Can not Serialize Class data.
        emp.eno = 77;
        emp.name = "Yash";
        emp.password = "confidential";
        objects_WriteRead(emp, fileName);

        Emp e = new Emp( );
        e.eno = 77;
        e.name = "Yash";
        e.password = "confidential";
        objects_WriteRead_External(e, fileName);

        /*String stubHost = "127.0.0.1";
        Integer anyFreePort = 7777;
        socketRead(anyFreePort); //Thread1
        socketWrite(emp, stubHost, anyFreePort); //Thread2*/

    }
    public static void objects_WriteRead( Employee obj, String serFilename ) throws IOException{
        FileOutputStream fos = new FileOutputStream( new File( serFilename ) );
        ObjectOutputStream objectOut = new ObjectOutputStream( fos );
        objectOut.writeObject( obj );
        objectOut.close();
        fos.close();

        System.out.println("Data Stored in to a file");

        try {
            FileInputStream fis = new FileInputStream( new File( serFilename ) );
            ObjectInputStream ois = new ObjectInputStream( fis );
            Object readObject;
            readObject = ois.readObject();
            String calssName = readObject.getClass().getName();
            System.out.println("Restoring Class Name : "+ calssName); // InvalidClassException

            Employee emp = (Employee) readObject;
            System.out.format("Obj[No:%s, Name:%s, Pass:%s]", emp.eno, emp.name, emp.password);

            ois.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    public static void objects_WriteRead_External( Emp obj, String serFilename ) throws IOException {
        FileOutputStream fos = new FileOutputStream(new File( serFilename ));
        ObjectOutputStream objectOut = new ObjectOutputStream( fos );

        obj.writeExternal( objectOut );
        objectOut.flush();

        fos.close();

        System.out.println("Data Stored in to a file");

        try {
            // create a new instance and read the assign the contents from stream.
            Emp emp = new Emp();

            FileInputStream fis = new FileInputStream(new File( serFilename ));
            ObjectInputStream ois = new ObjectInputStream( fis );

            emp.readExternal(ois);

            System.out.format("Obj[No:%s, Name:%s, Pass:%s]", emp.eno, emp.name, emp.password);

            ois.close();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
}

可通过网络序列化的例子

将对象的状态分布在不同的地址空间中，或者在同一台计算机上的不同进程中，或者甚至在通过网络连接的多台计算机中，但它们通过共享数据和调用方法一起工作。

数据编组 残根和骷髅

/**
 * Creates a stream socket and connects it to the specified port number on the named host. 
 */
public static void socketWrite(Employee objectToSend, String stubHost, Integer anyFreePort) {
    try { // CLIENT - Stub[marshalling]
        Socket client = new Socket(stubHost, anyFreePort);
        ObjectOutputStream out = new ObjectOutputStream(client.getOutputStream());
        out.writeObject(objectToSend);
        out.flush();
        client.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}
// Creates a server socket, bound to the specified port. 
public static void socketRead(  Integer anyFreePort ) {
    try { // SERVER - Stub[unmarshalling ]
        ServerSocket serverSocket = new ServerSocket( anyFreePort );
        System.out.println("Server serves on port and waiting for a client to communicate");
            /*System.in.read();
            System.in.read();*/

        Socket socket = serverSocket.accept();
        System.out.println("Client request to communicate on port server accepts it.");

        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
        Employee objectReceived = (Employee) in.readObject();
        System.out.println("Server Obj : "+ objectReceived.name );

        socket.close();
        serverSocket.close();
    } catch (IOException | ClassNotFoundException e) {
        e.printStackTrace();
    }
}

@see

实现Serializable和Externalizable

序列化是通过将对象转换为字节码来保存对象的特定状态的过程。转换后的字节码用于在2个JVM之间传输对象状态，接收JVM在其中反序列化字节码以检索共享对象的状态。 序列化和反序列化是使用serialVersionUID作为相关jvm中的引用来完成的。

在Java中，使用Serialization和Externalisation接口也可以实现同样的功能