确保正确完成对象的序列化

Question

有没有办法确保对象的序列化正确完成？我创建了一个我用writeObject()方法序列化的applet,我没有Exception没有错误.但是当我尝试对它进行反序列化时,readObject()我得到了一个N​​ullPointerException.我的applet有点复杂,但我确保我的所有字段都是可序列化的.

异议的类具有嵌套类.

有什么可能发生的猜测吗？

下面的代码在我的servlet中创建了一个SerialTree.

` SerialTree st = new SerialTree() ;

     try{
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("/home/cof/test8"));

 out.writeUnshared(st);
 out.flush();
 out.close();

}

这是堆栈跟踪:

java.lang.NullPointerException at java.awt.Container.readObject(Container.java:3575) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.access$300(ObjectInputStream.java:205) at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2125) at java.io.ObjectInputStream.readFields(ObjectInputStream.java:536) at java.awt.Container.readObject(Container.java:3560) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.access$300(ObjectInputStream.java:205) at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2125) at java.io.ObjectInputStream.readFields(ObjectInputStream.java:536) at java.awt.Container.readObject(Container.java:3560) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.access$300(ObjectInputStream.java:205) at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2125) at java.io.ObjectInputStream.readFields(ObjectInputStream.java:536) at java.awt.Container.readObject(Container.java:3560) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.access$300(ObjectInputStream.java:205) at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2125) at java.io.ObjectInputStream.readFields(ObjectInputStream.java:536) at java.awt.Container.readObject(Container.java:3560) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.access$300(ObjectInputStream.java:205) at java.io.ObjectInputStream$GetFieldImpl.readFields(ObjectInputStream.java:2125) at java.io.ObjectInputStream.readFields(ObjectInputStream.java:536) at java.awt.Container.readObject(Container.java:3560) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:616) at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:991) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1865) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1684) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1340) at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1963) at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1887) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1770) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:368) at arbre.ArbreClient.getHttpObject(ArbreClient.java:92) at arbre.ArbreClient.init(ArbreClient.java:123) at sun.applet.AppletPanel.run(AppletPanel.java:436) at java.lang.Thread.run(Thread.java:636)

这里是applet本身的第70到106行,它试图检索一个serilaTree对象？

`try {result = new ObjectInputStream(new FileInputStream("/ home/cof/test8"));

}
 catch(NotSerializableException e){

     e.printStackTrace();
 }

 catch(InvalidClassException e){
     e.printStackTrace();
 }
 catch(StreamCorruptedException e){

     e.printStackTrace();
 }
 catch(NotActiveException e){

     e.printStackTrace();
 }
 catch(OptionalDataException  e){

     e.printStackTrace();
 }

Object obj =null;

    try{

obj = result.readObject(); 

    }
    catch(NullPointerException e){

     e.printStackTrace();
    // System.out.println("lalal");
 }
 catch(NotSerializableException e){

     e.printStackTrace();
 }
 catch(InvalidClassException e){

     e.printStackTrace();
 }
 catch(StreamCorruptedException e){

     e.printStackTrace();
 }

Answer 1

对我来说,对Applet类型进行ser/deser是没有意义的.尝试使用其他类.

更新: 我已经阅读了您的堆栈跟踪,我看到的是您在运行applet时尝试反序列化小程序.我强烈怀疑这是你问题的原因.尝试将所有变量移动到另一个类中(MySerializableApplet例如,调用它,不要使它扩展类Applet),然后仅在此类上运行序列化/反序列化.