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ObjectInputStream用法

热度:2136   发布时间:2013-02-25 00:00:00.0
求助ObjectInputStream用法
第一次用这个字节流 如下

Java code
import java.io.*;class Student implements Serializable{    private String name;    public Student(String name){        this.name=name;    }    public String getName(){        return this.name;    }    public String toString(){        return "姓名:"+this.name;    }}public class MyDemo{     public static void main(String[] args) throws IOException, ClassNotFoundException{        FileOutputStream fos=new FileOutputStream("m.dat");        ObjectOutputStream oos=new ObjectOutputStream(fos);        oos.writeObject(new Student("ahah"));        oos.writeObject(new Student("papa"));        System.out.println("ok!");        oos.close();        fos.close();    //            FileInputStream fis=new FileInputStream("m.dat");        ObjectInputStream ois=new ObjectInputStream(fis);        while(ois.readObject()!=null){//这一行错了,是为什么?            Student stu1=(Student)ois.readObject();            System.out.println(stu1);        }        ois.close();        fis.close();        }}

为什么结果只显示了第二个对象?
Java code
ok!姓名:papaException in thread "main" java.io.EOFException    at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2571)    at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1315)    at java.io.ObjectInputStream.readObject(ObjectInputStream.java:369)    at MyDemo.main(MyDemo.java:27)


------解决方案--------------------------------------------------------
while(ois.readObject()!=null){//这一行错了,是为什么? 第一次读取了ahah
Student stu1=(Student)ois.readObject();//这次读取了papa
System.out.println(stu1);
}然后再去执行循环 while(ois.readObject //第三次读取报错。
你仔细看看这句话,里面只有两个对象,你读取了两次。第三次去读取的时候当然到达文件末端了)end of file )EOFExcepiton了。
------解决方案--------------------------------------------------------
改一下可以了.
Java code
public class MyDemo{     public static void main(String[] args) throws IOException, ClassNotFoundException{        FileOutputStream fos=new FileOutputStream("m.dat");        ObjectOutputStream oos=new ObjectOutputStream(fos);        oos.writeObject(new Student("ahah"));        oos.writeObject(new Student("papa"));        System.out.println("ok!");        oos.close();        fos.close();    //            FileInputStream fis=new FileInputStream("m.dat");        ObjectInputStream ois=new ObjectInputStream(fis);    Student s;                    //定义Student类变量.        while((fis.available()>0)&&(s=            //判断是否到文件尾。                (Student)ois.readObject())!=null){            //Student stu1=(Student)ois.readObject();    //再运行就读了下一个了。            System.out.println(s);        }        ois.close();        fis.close();        }}