Java中SerialVersionUID关键字的重要性?
SerialVersionUID
在Java中,SerialVersionUID必须声明为私有的静态最终长变量。此数字由编译器根据类的状态和类属性计算。当JVM从文件中读取对象的状态时,该数字将帮助JVM识别对象的状态
在反序列化期间可以使用SerialVersionUID来验证序列化对象的发送方和接收方是否为该对象加载了与w.r.t序列化兼容的类。如果反序列化对象与序列化不同,则它可以引发InvalidClassException。
如果未指定serialVersionUID, 则运行时将根据类的各个方面来计算该类的默认serialVersionUID值 。
示例
import java.io.*; class Employee implements Serializable { private static final long serialVersionUID = 5462223600l; int empId; String name; String location; Employee(int empId, String name, String location) { this.empId = empId; this.name = name; this.location = location; } void empData() { System.out.println("Employee Id is: "+ empId); System.out.println("Employee Name is: "+ name); System.out.println("Employee Location is: "+ location); } } public class EmployeeTest { public static void main(String[] args)throws Exception{ Employee emp = new Employee(115, "Raja", "Hyderabad"); emp.empData(); FileOutputStream fos = new FileOutputStream("E:\\Employee.txt"); ObjectOutputStream oos = new ObjectOutputStream(fos); oos.writeObject(emp); System.out.println("Object Serialized"); } }
输出结果
Employee Id is: 115 Employee Name is: Raja Employee Location is: Hyderabad Object Serialized