Question

java序列化当中重写readObject当中为什么执行时出现异常？出现异常的地方在下面有标记....谢谢

import java.io.*;
class ObjectSerialTest
{
public static void main(String[] args) throws Exception
{
Employee e1=new Employee("zhangsan",25,3000.50);
Employee e2=new Employee("lisi",24,3100.40);
Employee e3=new Employee("wangwu",26,3800.60);

FileOutputStream fos=new FileOutputStream("employee.txt");
ObjectOutputStream oos=new ObjectOutputStream(fos);
oos.writeObject(e1);
oos.writeObject(e2);
oos.writeObject(e3);
oos.close();

FileInputStream fis=new FileInputStream("employee.txt");
ObjectInputStream ois=new ObjectInputStream(fis);
Employee e;
for(int i=0;i<3;i++)
{
e=(Employee) ois.readObject();//为什么这里会抛出异常无法正常执行？
System.out.println(e.name+" "+e.age+" "+e.salary);
}
ois.close();
}
}
class Employee implements Serializable
{
String name;
int age;
double salary;
transient Thread t=new Thread();
public Employee(String name,int age,double salary)
{
this.name=name;
this.age=age;
this.salary=salary;
}
private void writeObject(java.io.ObjectOutputStream oos)throws IOException
{
oos.writeInt(age);
oos.writeUTF(name);
System.out.println("write object");
}
private void readObeject(java.io.ObjectInputStream ois) throws IOException,ClassNotFoundException
{
age=ois.readInt();
name=ois.readUTF();
System.out.println("read object");
}

}

Answer 1

因为你readObject写成了readObeject,还有你没有写入和读出对象的salary属性，我给你加上了，你看看吧，运行没问题。完整的程序如下：
import java.io.*;
class ObjectSerialTest
{
public static void main(String[] args) throws Exception
{
Employee e1=new Employee("zhangsan",25,3000.50);
Employee e2=new Employee("lisi",24,3100.40);
Employee e3=new Employee("wangwu",26,3800.60);

FileOutputStream fos=new FileOutputStream("employee.txt");
ObjectOutputStream oos=new ObjectOutputStream(fos);
oos.writeObject(e1);
oos.writeObject(e2);
oos.writeObject(e3);
oos.close();

FileInputStream fis=new FileInputStream("employee.txt");
ObjectInputStream ois=new ObjectInputStream(fis);
Employee e;
for(int i=0;i<3;i++)
{
e=(Employee) ois.readObject();//为什么这里会抛出异常无法正常执行？
System.out.println(e.name+" "+e.age+" "+e.salary);
}
ois.close();
}
}
class Employee implements Serializable
{
String name;
int age;
double salary;
transient Thread t=new Thread();
public Employee(String name,int age,double salary)
{
this.name=name;
this.age=age;
this.salary=salary;
}
private void writeObject(java.io.ObjectOutputStream oos)throws IOException
{
oos.writeInt(age);
oos.writeUTF(name);
oos.writeDouble(salary);
System.out.println("write object");
}
private void readObject(java.io.ObjectInputStream ois) throws IOException,ClassNotFoundException
{
age=ois.readInt();
name=ois.readUTF();
salary=ois.readDouble();
System.out.println("read object");
}

}
运行结果：
write object
write object
write object
read object
zhangsan 25 3000.5
read object
lisi 24 3100.4
read object
wangwu 26 3800.6

Answer 2

FileInputStream fis=new FileInputStream("employee.txt");
ObjectInputStream ois=new ObjectInputStream(fis);
Employee e;

你在这个fis读取这个流时，那个文件是空的。
所以在取得第一行的时候没有取到值。就报错了
invalid type code: 67