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通过示例解释序列化和反序列化-Java

news 2025/8/20 16:34:09

序列化和反序列化是Java（以及通常的编程）中涉及将对象转换为字节流，以及反之的过程。当你需要传输或存储对象的状态时特别有用，比如将其通过网络发送或持久化到文件中。

序列化：

定义：序列化是将对象的状态（字段和数据）转换为字节流的过程。
目的：它允许保存对象的状态，以便以后可以重建它。
Java接口：SerializableJava中的接口是一个标记接口，表示一个类可以被序列化。

反序列化：

定义：反序列化是从字节流重建对象的过程。
目的：它允许从保存的状态重新创建原始对象。
Java 接口：实现的类Serializable应该被反序列化。

用途和实时应用：

网络通讯：
用例：当需要通过网络在不同应用程序或系统之间发送对象时。
示例：客户端-服务器应用程序，其中对象在客户端和服务器之间发送。

import java.io.*;
import java.net.*;public class User implements Serializable {private String username;private transient String password; // Transient fields are not serialized// Constructors, getters, setters...public static void main(String[] args) {// Serialization (Client Side)try (Socket socket = new Socket("server_address", 12345);ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream())) {User user = new User("john_doe", "password123");out.writeObject(user);System.out.println("User object sent to server");} catch (IOException e) {e.printStackTrace();}// Deserialization (Server Side)try (ServerSocket serverSocket = new ServerSocket(12345);Socket clientSocket = serverSocket.accept();ObjectInputStream in = new ObjectInputStream(clientSocket.getInputStream())) {User receivedUser = (User) in.readObject();System.out.println("Received User object: " + receivedUser);} catch (IOException | ClassNotFoundException e) {e.printStackTrace();}}
}

持久化：

用例：将对象的状态存储在文件或数据库中，以便以后检索。
示例：将用户偏好或游戏状态保存在文件中。

import java.io.*;public class UserPreferences implements Serializable {private String theme;private int fontSize;// Constructors, getters, setters...public static void main(String[] args) {// Serialization (Save Preferences)try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("user_preferences.ser"))) {UserPreferences preferences = new UserPreferences("dark", 16);out.writeObject(preferences);System.out.println("User preferences saved to file");} catch (IOException e) {e.printStackTrace();}// Deserialization (Load Preferences)try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("user_preferences.ser"))) {UserPreferences loadedPreferences = (UserPreferences) in.readObject();System.out.println("Loaded User preferences: " + loadedPreferences);} catch (IOException | ClassNotFoundException e) {e.printStackTrace();}}
}

缓存：

用例：将对象存储在缓存中，以便快速检索而无需重新创建它们。
示例：缓存频繁使用的数据库查询结果。

import java.io.*;
import java.util.HashMap;
import java.util.Map;public class CacheManager implements Serializable {private Map<String, Object> cache = new HashMap<>();// Methods to put, get, and manage the cache...public static void main(String[] args) {// Serialization (Save Cache)try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("cache.ser"))) {CacheManager cacheManager = new CacheManager();cacheManager.put("queryResult1", /* database query result */);cacheManager.put("queryResult2", /* another query result */);out.writeObject(cacheManager);System.out.println("Cache saved to file");} catch (IOException e) {e.printStackTrace();}// Deserialization (Load Cache)try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("cache.ser"))) {CacheManager loadedCacheManager = (CacheManager) in.readObject();System.out.println("Loaded Cache: " + loadedCacheManager);} catch (IOException | ClassNotFoundException e) {e.printStackTrace();}}
}

消息队列：

用例：在不同组件或微服务之间传递对象。
示例：使用消息队列在分布式系统的不同部分之间发送对象。

import java.io.*;
import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;public class MessageQueue implements Serializable {private Queue<String> messages = new ArrayBlockingQueue<>(10);// Methods to add, retrieve, and manage messages...public static void main(String[] args) {// Serialization (Save Message Queue)try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("message_queue.ser"))) {MessageQueue messageQueue = new MessageQueue();messageQueue.addMessage("Message1");messageQueue.addMessage("Message2");out.writeObject(messageQueue);System.out.println("Message Queue saved to file");} catch (IOException e) {e.printStackTrace();}// Deserialization (Load Message Queue)try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("message_queue.ser"))) {MessageQueue loadedMessageQueue = (MessageQueue) in.readObject();System.out.println("Loaded Message Queue: " + loadedMessageQueue);} catch (IOException | ClassNotFoundException e) {e.printStackTrace();}}
}

远程方法调用（RMI）：

用例：像调用本地方法一样在远程对象上调用方法。
示例：分布式应用程序中，一个机器上的对象需要调用另一个机器上对象的方法。

import java.rmi.*;
import java.rmi.registry.*;public interface RemoteCalculator extends Remote {int add(int a, int b) throws RemoteException;// Other remote methods...
}public class CalculatorImpl implements RemoteCalculator {public int add(int a, int b) throws RemoteException {return a + b;}// Other method implementations...
}public class RmiServer {public static void main(String[] args) {try {RemoteCalculator calculator = new CalculatorImpl();Registry registry = LocateRegistry.createRegistry(1099);Naming.rebind("CalculatorService", calculator);System.out.println("RMI Server is running...");} catch (Exception e) {e.printStackTrace();}}
}public class RmiClient {public static void main(String[] args) {try {RemoteCalculator calculator = (RemoteCalculator) Naming.lookup("rmi://localhost/CalculatorService");int result = calculator.add(5, 10);System.out.println("Result from RMI server: " + result);} catch (Exception e) {e.printStackTrace();}}
}