在恢复一个Externalizable对象时,为什么对象的构造器不是public的访问权限就造成异常呢?
import java.io.*;class Blip1 implements Externalizable {
public Blip1() {
System.out.println("Blip1 Constructor");
}public void writeExternal(ObjectOutput out) throws IOException { System.out.println("Blip1.writeExternal"); } public void readExternal(ObjectInput in) throws IOException,ClassNotFoundException { System.out.println("Blip1.readExternal"); }
}
class Blip2 implements Externalizable {
Blip2() {
System.out.println("Blip2 Constructor");
}public void writeExternal(ObjectOutput out) throws IOException { System.out.println("Blip2.writeExternal"); } public void readExternal(ObjectInput in) throws IOException,ClassNotFoundException { System.out.println("Blip2.readExternal"); }
}
public class Blips {public static void main(String[] args) throws IOException, ClassNotFoundException{ System.out.println("Constucting objects:"); Blip1 b1=new Blip1(); Blip2 b2=new Blip2(); ObjectOutputStream o=new ObjectOutputStream(new FileOutputStream("Blips.out")); System.out.println("saving objects;"); o.writeObject(b1); o.writeObject(b2); o.close(); ObjectInputStream in=new ObjectInputStream(new FileInputStream("Blips.out")); System.out.println("Recovoring b1:"); b1=(Blip1)in.readObject(); //System.out.println("Recovoring b2:"); //b2=(Blip2)in.readObject(); }
}
被注释掉的两句话就会导致java.io.InvalidClassException异常,大家帮看看是什么原因?