将对象转换为字节数组引发NotSerializableException

Question

下面的代码抛出java.io.NotSerializableException。为什么？谢谢!

private void test3() {
   Element3 element3=new Element3();
   ObjectToBytes3(element3);
}

private class Element3 implements Serializable{
  int code=0;
}

//-----------------------------------
private void ObjectToBytes3(Element3 elem){
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream out = null;
    try {
        out = new ObjectOutputStream(bos);
        out.writeObject(elem);
        byte[] myBytes = bos.toByteArray();
    }
    catch (Exception e) {myPrint("exception",e.toString());}
    finally {
        try{
            out.flush();
            out.close();
            bos.close();
        }
        catch (Exception e) {}
    }
}

输出和堆栈如下: 2674,25 ObjToBytes: 2674,32例外: java.io.NotSerializableException: java.util.concurrent.ThreadPoolExecutor stack= java.io.NotSerializableException: java.util.concurrent.ThreadPoolExecutor at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400) at java.io.ObjectOutputStream.writeObject0( java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330) )

很有趣，但下面的代码工作正常

================================
class My implements Serializable{
    byte a=1;
    int b=88;
    String s="ggg";
    private My(byte a1, int b1,String s1) {
        a=a1;
        b=b1;
        s=s1;
    }
}

private void test() {
    My my=new My((byte)5,10,"jjj");
    ObjectToBytesTest(my);
}

//-----------------------------------
private void ObjectToBytesTest(My my){
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    ObjectOutputStream out = null;
    try {
        out = new ObjectOutputStream(bos);
        out.writeObject(element);
        byte[] myBytes = bos.toByteArray();
    }
    catch (Exception e) {print("exception",e.toString());}
    finally {
        try{
            out.flush();
            out.close();
            bos.close();
        }
        catch (Exception e) {}
    }
}

Answer 1

这是因为Element3实例elem有一个对outter对象的隐式引用。

当序列化Element3使用可序列化接口的默认操作时，它将序列化outter对象，而outter对象尚未实现可序列化接口，因此它将抛出java.io.NotSerializableException。

异常将引用未实现可序列化接口的outter对象类。

在我的代码中，它是：java.io.NotSerializableException: serializable.ObjectToBytesTest

要解决这个问题，您应该将Element3类移出outter类，如下所示：

    public class ObjectToBytesTest {
      private void ObjectToBytes3() { ... }
    }

    class Element3 implements Serializable {
        int code=0;
    }

或者就像您的解决方案一样(我的类实现了可序列化接口)，但是我认为这个解决方案是不推荐的。