java 序列化 51cto-CFANZ编程社区

Java序列化教程

1. 简介

在Java编程中，序列化是指将对象转换为字节流的过程，以便在网络上传输或将其保存到磁盘上。反序列化则是将字节流转换回对象的过程。本文将教会你如何在Java中进行序列化。

2. 序列化的流程

下面是Java序列化的整个流程，通过表格展示了每个步骤所需的代码和注释。

步骤	代码	注释
1. 创建要序列化的类	`java public class Employee implements Serializable { private String name; private String address; private transient int age; }`	创建一个包含需要序列化的属性的类。注意，需要实现`Serializable`接口。对于不希望被序列化的属性，可以使用`transient`关键字修饰
2. 序列化对象	`java try { FileOutputStream fileOut = new FileOutputStream("employee.ser"); ObjectOutputStream out = new ObjectOutputStream(fileOut); out.writeObject(employee); out.close(); fileOut.close(); } catch (IOException i) { i.printStackTrace(); }`	创建`FileOutputStream`和`ObjectOutputStream`对象，将对象写入文件。`employee`是需要序列化的对象
3. 反序列化对象	`java try { FileInputStream fileIn = new FileInputStream("employee.ser"); ObjectInputStream in = new ObjectInputStream(fileIn); Employee employee = (Employee) in.readObject(); in.close(); fileIn.close(); } catch (IOException i) { i.printStackTrace(); } catch (ClassNotFoundException c) { System.out.println("Employee class not found"); c.printStackTrace(); }`	创建`FileInputStream`和`ObjectInputStream`对象，从文件中读取对象。需要使用`readObject()`方法将对象转换回原始类型
4. 使用序列化后的对象	`java System.out.println("Name: " + employee.getName()); System.out.println("Address: " + employee.getAddress()); System.out.println("Age: " + employee.getAge());`	使用反序列化后的对象，访问其属性和方法

3. 类图

下面是使用mermaid语法绘制的类图，显示了Employee类的属性和方法：

classDiagram
    class Employee {
        - name: String
        - address: String
        - age: int
        + getName(): String
        + getAddress(): String
        + getAge(): int
    }

4. 状态图

下面是使用mermaid语法绘制的状态图，展示了Employee对象的状态变化：

stateDiagram
    [*] --> Uninitialized
    Uninitialized --> Serialized: Serialization
    Serialized --> Deserialized: Deserialization
    Deserialized --> [*]

5. 完整示例代码

下面是完整的示例代码，包括了定义Employee类、序列化和反序列化对象以及使用对象的代码：

import java.io.*;

public class SerializationExample {
    public static void main(String[] args) {
        // Step 1: Create an Employee object
        Employee employee = new Employee();
        employee.setName("John Doe");
        employee.setAddress("123 Main St");
        employee.setAge(30);

        // Step 2: Serialize the object
        try {
            FileOutputStream fileOut = new FileOutputStream("employee.ser");
            ObjectOutputStream out = new ObjectOutputStream(fileOut);
            out.writeObject(employee);
            out.close();
            fileOut.close();
            System.out.println("Serialized data is saved in employee.ser");
        } catch (IOException i) {
            i.printStackTrace();
        }

        // Step 3: Deserialize the object
        try {
            FileInputStream fileIn = new FileInputStream("employee.ser");
            ObjectInputStream in = new ObjectInputStream(fileIn);
            Employee deserializedEmployee = (Employee) in.readObject();
            in.close();
            fileIn.close();
            System.out.println("Deserialized data:");
            System.out.println("Name: " + deserializedEmployee.getName());
            System.out.println("Address: " + deserializedEmployee.getAddress());
            System.out.println("Age: " + deserializedEmployee.getAge());
        } catch (IOException i) {
            i.printStackTrace();
        } catch (ClassNotFoundException c) {
            System.out.println("Employee class not found");
            c.printStackTrace();
        }
    }
}

class Employee implements Serializable {
    private String name;
    private String address;
    private transient int age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getAge() {
        return age;