参考：

public void testDeserialize() throws IOException, ClassNotFoundException {        ByteArrayOutputStream baos = new ByteArrayOutputStream();        ObjectOutputStream oos = new ObjectOutputStream(baos);        BigInteger bi = new BigInteger("0");        oos.writeObject(bi);        byte[] str = baos.toByteArray();        ObjectInputStream ois = new ObjectInputStream(new BufferedInputStream(new ByteArrayInputStream(str)));        Object obj = ois.readObject();        assertNotNull(obj);        assertEquals(obj.getClass().getName(),"java.math.BigInteger");        assertEquals(((BigInteger)obj).intValue(), 0);    }

关键处理

byte[] str = baos.toByteArray();