关于ObjectInputStream的问题

[dingjikun]

import java.io.*;

public class TestObjectIO {
public static void main(String args[]) throws Exception {
/*T t = new T("kkkkkkk");
t.k = 8;
FileOutputStream fos = new FileOutputStream("f:/testobjectio.txt", true);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(t);
oos.flush();
oos.close();*/注释

FileInputStream fis = new FileInputStream("f:/testobjectio.txt");
ObjectInputStream ois = new ObjectInputStream(fis);
T tReaded = (T)ois.readObject();
T tReaded1 = (T)ois.readObject();
T tReaded2 = (T)ois.readObject();
System.out.println(tReaded.s + " " + tReaded.s + " " + tReaded.s + " " + tReaded.d);

}
}

class T
implements Serializable
{
T(String s)
{
this.s = s;
}
String s = null;
int i = 10;
int j = 9;
double d = 2.3;
transient int k = 15;
}
我用注释里的代码写了一个保存类的文件 里面保存了4个T类 将其注释掉后在下面想读出 可出现了如下错误
Exception in thread "main" java.io.StreamCorruptedException: invalid type code: AC
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at TestObjectIO.main(TestObjectIO.java:16)
请高手指导下~另对于ObjectInputStream封装的文件里的指针不太清楚 麻烦帮解释下 如何控制读取文件中类的顺序

[dingjikun]

请大家帮帮忙啊~~~~~~~~~~~~·

[treeroot]

感觉没啥问题，看不出保存了多少个对象，存在三个对象吗

[dingjikun]

恩 是在文件中事先存了3个对象 存了3次 想一次读出 找到问题了 是writeStreamHeader（）的问题 可到了重写header的时候又出现问题了，下面是改进的
import java.io.*;

public class TestObjectIO {
public static void main(String args[]) throws Exception {
File f = new File("f:/dance.txt");
int flag = 0;
T t = new T();
t.k = 8;
FileOutputStream fos = new FileOutputStream(f, true);
if (f.length() == 0)
{
flag = 1;
}
FileObjectOutputStream oos = new FileObjectOutputStream(fos,flag);
oos.writeObject(t);
oos.flush();
oos.close();

FileInputStream fis = new FileInputStream(f);
ObjectInputStream ois = new ObjectInputStream(fis);
T tReaded = (T)ois.readObject();
System.out.println(tReaded.i + " " + tReaded.j + " " + tReaded.d + " " + tReaded.k);

}
}

class T
implements Serializable
{
int i = 10;
int j = 9;
double d = 2.3;
transient int k = 15;
}

class FileObjectOutputStream extends ObjectOutputStream
{
private int flag = 0;
FileObjectOutputStream(OutputStream os, int i) throws Exception
{
super(os);
flag = i;
}
protected void writeStreamHeader()
throws IOException{
if (flag == 0)
{
super.reset();
}
else
{
super.writeStreamHeader();
}
}
}
可好像还不对~~~ 对reset（）的使用不太了解 能讲下它的使用和作用吗？？？

[yuanrong303]

T t=new T("kkkkkkk"); 
t.k=8; 
FileOutputStream fos=new FileOutputStream("f:/testobjectio.txt",true); 
ObjectOutputStream oos=new ObjectOutputStream(fos); 
oos.writeObject(t); 
oos.flush(); 
oos.close();*/

上面代码每次写入对象的时候把以前写的覆盖了，所以你保存的文件里面是没有四个T对象的。
这样你再次读入的时候，后面两个readObject（）读不到的，里面文件指针已经读入为null!

[rain_night]

在T类中重写String toString方法，解决问题

public String toString(){
		return this.s+this.d+this.i+this.j+this.k;
	}

[xiaoyu_air]

次数问题.

import java.io.*;

public class TestObjectIO {
public static void main(String args[]) throws Exception {
T t = new T("kkkkkkk");
t.k = 8;
FileOutputStream fos = new FileOutputStream("d:/testobjectio.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(t);
oos.flush();
oos.writeObject(t);
oos.flush();
oos.writeObject(t);
oos.flush();
oos.close();

FileInputStream fis = new FileInputStream("d:/testobjectio.txt");
ObjectInputStream ois = new ObjectInputStream(fis);
T tReaded = (T) ois.readObject();
T tReaded1 = (T) ois.readObject();
T tReaded2 = (T) ois.readObject();
System.out.println(tReaded.s + " " + tReaded.s + " " + tReaded.s
+ " " + tReaded.d);
System.out.println(tReaded1.s + " " + tReaded1.s + " " + tReaded1.s
+ " " + tReaded1.d);
System.out.println(tReaded2.s + " " + tReaded2.s + " " + tReaded2.s
+ " " + tReaded2.d);

}
}

class T implements Serializable {
T(String s) {
this.s = s;
}

String s = null;
int i = 10;
int j = 9;
double d = 2.3;
transient int k = 15;
}