通過實現Serializable接口，可以讓一個類的擁有序列化和反序列化的能力。可序列化類的所有子類，都可以序列化。這個接口沒有任何的方法定義，它僅僅只是標記某個類能被序列化和反序列化。
想讓一個非序列化類的子類擁有序列化能力，這個子類在反序列化的時候，需要恢復父類的public、protected以及其它可以訪問的字段，子類通過調用父類的無參構造方法，在反序列化的時候，恢復父類（可訪問）字段。如果不是這樣，子類將無法實現序列化（這種錯誤將會在運行時階段被jvm發現）。子類自己的字段，則通過存儲在序列化流中的數據來恢復值。
類在序列化和反序列化過程中，如果需要做一些特殊處理，則需要實現下列的方法：
private void writeObject(java.io.ObjectOutputStream out) throws IOException
private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException;
private void readObjectNoData() throws ObjectStreamException;
writeObject方法負責將對象的字段的值寫入序列化流中，而對應readObject方法則負責恢復對象字段的值。可以通過調用out.defaultWriteObject方法來使用默認的序列化機制。這個方法不需要關注父類或子類的字段。writeObject方法將字段的值寫入到ObjectOutputStream流中，來達到保存的目的。對於原始數據類型的字段，則通過DataOutput提供的方法來實現保存。
readObject方法負責從流中讀取數據，然後按照字段名稱恢復對象的字段值。可以通過調用in.defaultReadObject方法來啓用默認的反序列化機制：恢復非static和非transient字段。readObject方法不需要關注父類或子類的字段。
當出現反序列化與序列化類的版本不一致的情況時，readObjectNoData方法負責初始化對象的字段值。這種情況可能發生在：反序列化時，接收方使用了發送方對象的類的不同版本，或者接收方繼承的類的版本與發送方繼承的類的版本不一致。另外，當序列化流被篡改了，也會發生這種情況。因此，當出現類不一致或者反序列化流不完全的情況時，readObjectNoData初始化反序列化對象的字段就非常有用。
在將對象寫入序列化流時，如果替換成另一個對象寫入流，則需要重寫如下方法：
ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException;
1
如果writeReplace方法存在，而且它能夠被對象的其它成員方法訪問，則它會被序列化機制調用。因此，這個方法可以是private, protected和package-private。
反序列化時，如果需要替換成另一個對象，則需要重寫如下方法：
ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException;
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readResolve的調用方式及可訪問特性與writeReplace一樣。
序列化機制會給每個能被序列化的類關聯一個數字類型的版本號，版本號的名字是：serialVersionUID，這個版本號，用於在反序列化時，檢測發送方和接收方所使用的對象的類是否一致。如果接收方加載的類與發送方加載的類的serialVersionUID不一致，則反序列化時會拋出InvalidClassException異常。一個可序列化類可以通過明確的定義一個long類型的，使用static和final修飾的”serialVersionUID”字段，來指定它的版本號。如下所示：
ANY-ACCESS-MODIFIER static final long serialVersionUID = 42L;
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如果一個可序列化類沒有明確的定義一個serialVersionUID字段，則序列化運行時會爲類計算出一個默認的serialVersionUID值。但是強烈建議爲每個可序列化的類明確的定義serialVersionUID，因爲默認的serialVersionUID值過多依賴類的細節和編譯環境，很容易導致反序列化過程中拋出InvalidClassException異常。因此，想要讓序列化和反序列化兼容各種不同的編譯環境，就需要爲類定義一個serialVersionUID字段。由於serialVersionUID只是標記當前類本身的版本，不適用於繼承機制，因此，強烈建議將serialVersionUID字段定義成private的。無法爲數組對象（如int[], Integer[], Object[]等）定義serialVersionUID，因此它們使用默認的版本號，但是數組對象反序列化過程中對比serialVersionUID的機制已經被廢棄了。
Serializable源碼如下：
/*
* %W% %E%
*
* Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.io;
/**
* Serializability of a class is enabled by the class implementing the
* java.io.Serializable interface. Classes that do not implement this
* interface will not have any of their state serialized or
* deserialized. All subtypes of a serializable class are themselves
* serializable. The serialization interface has no methods or fields
* and serves only to identify the semantics of being serializable. <p>
*
* To allow subtypes of non-serializable classes to be serialized, the
* subtype may assume responsibility for saving and restoring the
* state of the supertype's public, protected, and (if accessible)
* package fields. The subtype may assume this responsibility only if
* the class it extends has an accessible no-arg constructor to
* initialize the class's state. It is an error to declare a class
* Serializable if this is not the case. The error will be detected at
* runtime. <p>
*
* During deserialization, the fields of non-serializable classes will
* be initialized using the public or protected no-arg constructor of
* the class. A no-arg constructor must be accessible to the subclass
* that is serializable. The fields of serializable subclasses will
* be restored from the stream. <p>
*
* When traversing a graph, an object may be encountered that does not
* support the Serializable interface. In this case the
* NotSerializableException will be thrown and will identify the class
* of the non-serializable object. <p>
*
* Classes that require special handling during the serialization and
* deserialization process must implement special methods with these exact
* signatures: <p>
*
* <PRE>
* private void writeObject(java.io.ObjectOutputStream out)
* throws IOException
* private void readObject(java.io.ObjectInputStream in)
* throws IOException, ClassNotFoundException;
* private void readObjectNoData()
* throws ObjectStreamException;
* </PRE>
*
* <p>The writeObject method is responsible for writing the state of the
* object for its particular class so that the corresponding
* readObject method can restore it. The default mechanism for saving
* the Object's fields can be invoked by calling
* out.defaultWriteObject. The method does not need to concern
* itself with the state belonging to its superclasses or subclasses.
* State is saved by writing the individual fields to the
* ObjectOutputStream using the writeObject method or by using the
* methods for primitive data types supported by DataOutput.
*
* <p>The readObject method is responsible for reading from the stream and
* restoring the classes fields. It may call in.defaultReadObject to invoke
* the default mechanism for restoring the object's non-static and
* non-transient fields. The defaultReadObject method uses information in
* the stream to assign the fields of the object saved in the stream with the
* correspondingly named fields in the current object. This handles the case
* when the class has evolved to add new fields. The method does not need to
* concern itself with the state belonging to its superclasses or subclasses.
* State is saved by writing the individual fields to the
* ObjectOutputStream using the writeObject method or by using the
* methods for primitive data types supported by DataOutput.
*
* <p>The readObjectNoData method is responsible for initializing the state of
* the object for its particular class in the event that the serialization
* stream does not list the given class as a superclass of the object being
* deserialized. This may occur in cases where the receiving party uses a
* different version of the deserialized instance's class than the sending
* party, and the receiver's version extends classes that are not extended by
* the sender's version. This may also occur if the serialization stream has
* been tampered; hence, readObjectNoData is useful for initializing
* deserialized objects properly despite a "hostile" or incomplete source
* stream.
*
* <p>Serializable classes that need to designate an alternative object to be
* used when writing an object to the stream should implement this
* special method with the exact signature: <p>
*
* <PRE>
* ANY-ACCESS-MODIFIER Object writeReplace() throws ObjectStreamException;
* </PRE><p>
*
* This writeReplace method is invoked by serialization if the method
* exists and it would be accessible from a method defined within the
* class of the object being serialized. Thus, the method can have private,
* protected and package-private access. Subclass access to this method
* follows java accessibility rules. <p>
*
* Classes that need to designate a replacement when an instance of it
* is read from the stream should implement this special method with the
* exact signature.<p>
*
* <PRE>
* ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException;
* </PRE><p>
*
* This readResolve method follows the same invocation rules and
* accessibility rules as writeReplace.<p>
*
* The serialization runtime associates with each serializable class a version
* number, called a serialVersionUID, which is used during deserialization to
* verify that the sender and receiver of a serialized object have loaded
* classes for that object that are compatible with respect to serialization.
* If the receiver has loaded a class for the object that has a different
* serialVersionUID than that of the corresponding sender's class, then
* deserialization will result in an {@link InvalidClassException}. A
* serializable class can declare its own serialVersionUID explicitly by
* declaring a field named <code>"serialVersionUID"</code> that must be static,
* final, and of type <code>long</code>:<p>
*
* <PRE>
* ANY-ACCESS-MODIFIER static final long serialVersionUID = 42L;
* </PRE>
*
* If a serializable class does not explicitly declare a serialVersionUID, then
* the serialization runtime will calculate a default serialVersionUID value
* for that class based on various aspects of the class, as described in the
* Java(TM) Object Serialization Specification. However, it is <em>strongly
* recommended</em> that all serializable classes explicitly declare
* serialVersionUID values, since the default serialVersionUID computation is
* highly sensitive to class details that may vary depending on compiler
* implementations, and can thus result in unexpected
* <code>InvalidClassException</code>s during deserialization. Therefore, to
* guarantee a consistent serialVersionUID value across different java compiler
* implementations, a serializable class must declare an explicit
* serialVersionUID value. It is also strongly advised that explicit
* serialVersionUID declarations use the <code>private</code> modifier where
* possible, since such declarations apply only to the immediately declaring
* class--serialVersionUID fields are not useful as inherited members. Array
* classes cannot declare an explicit serialVersionUID, so they always have
* the default computed value, but the requirement for matching
* serialVersionUID values is waived for array classes.
*
* @author unascribed
* @version %I%, %G%
* @see java.io.ObjectOutputStream
* @see java.io.ObjectInputStream
* @see java.io.ObjectOutput
* @see java.io.ObjectInput
* @see java.io.Externalizable
* @since JDK1.1
*/
public interface Serializable {
}