Java-反序列化包含基元类型的哈希表时出错
我使用Java-反序列化包含基元类型的哈希表时出错,java,serialization,hashtable,objectinputstream,objectoutputstream,Java,Serialization,Hashtable,Objectinputstream,Objectoutputstream,我使用ObjectOutputStream序列化了一个HashTable对象。序列化对象时,没有异常,但在反序列化时,会发生以下异常: Exception in thread "main" java.io.InvalidClassException: java.lang.Long; local class incompatible: stream classdesc serialVersionUID = 4290774032661291999, local class serialVersion
ObjectOutputStream
序列化了一个HashTable
对象。序列化对象时,没有异常,但在反序列化时,会发生以下异常:
Exception in thread "main" java.io.InvalidClassException: java.lang.Long; local class
incompatible: stream classdesc serialVersionUID = 4290774032661291999, local class
serialVersionUID = 4290774380558885855
当我删除哈希表
中具有非字符串
值的所有键时,不再出现错误(我删除的所有键/值对都有一个基元类型作为其值)
是什么导致了这个错误
更新-以下是代码
public static String serialize(Quiz quiz) throws IOException{
HashMap<String,Object> quizData = new HashMap<String,Object>();
quizData.put("version", 0); //int
quizData.put("name", quiz.getName()); //String
quizData.put("desc", quiz.getDesc()); //String
quizData.put("timelimitType", quiz.getTimelimitType()); //String
quizData.put("timelimit", quiz.getTimelimit()); //long
ArrayList<String> serializedQuestionsData = new ArrayList<String>();
for (Question question : quiz.getQuestions())
serializedQuestionsData.add(Question.serialize(question));
quizData.put("questions", serializedQuestionsData.toArray(new String[0])); //String[]
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ObjectOutputStream oos;
try { oos = new ObjectOutputStream(baos); } catch (IOException error){ throw error; }
try { oos.writeObject(quizData); } catch (IOException error){ throw error; }
return baos.toString();
}
@SuppressWarnings("unchecked")
public static Quiz deserialize(String serializedQuizData) throws IOException, ClassNotFoundException{
ByteArrayInputStream bais = new ByteArrayInputStream(serializedQuizData.getBytes());
ObjectInputStream ois;
try { ois = new ObjectInputStream(bais); } catch (IOException error){ throw error; }
HashMap<String,Object> quizData;
// Exception occurs on the following line!!
try { quizData = (HashMap<String,Object>) ois.readObject(); } catch (ClassNotFoundException error){ throw error; }
Quiz quiz;
if ((int) quizData.get("version") == 0){
quiz = new Quiz((String) quizData.get("name"),
(String) quizData.get("desc"),
(String) quizData.get("timelimitType"),
(long) quizData.get("timelimit"));
for (String serializedQuestionData : (String[]) quizData.get("questions"))
quiz.addQuestion(Question.deserialize(serializedQuestionData));
} else {
throw new UnsupportedOperationException("Unsupported version: \"" + quizData.get("version") + "\"");
}
return quiz;
}
公共静态字符串序列化(测验)引发IOException{
HashMap quizData=新的HashMap();
quizData.put(“版本”,0);//int
quizData.put(“name”,quick.getName());//字符串
quizData.put(“desc”,quick.getDesc());//字符串
quizData.put(“timelimitType”,quick.getTimelimitType());//字符串
quizData.put(“timelimit”,quick.getTimelimit());//长
ArrayList serializedQuestionsData=新ArrayList();
for(问题:quick.getQuestions())
serializedQuestionsData.add(问题.序列化(问题));
quizData.put(“questions”,serializedQuestionsData.toArray(新字符串[0]);//字符串[]
ByteArrayOutputStream bas=新的ByteArrayOutputStream();
对象输出流oos;
尝试{oos=newobjectoutputstream(baos);}catch(IOException error){throw error;}
尝试{oos.writeObject(quizData);}catch(IOException error){throw error;}
返回bas.toString();
}
@抑制警告(“未选中”)
公共静态测试反序列化(String serializedQuizData)引发IOException、ClassNotFoundException{
ByteArrayInputStream bais=新的ByteArrayInputStream(serializedQuizData.getBytes());
目的输入流ois;
尝试{ois=newobjectinputstream(bais);}catch(IOException error){throw error;}
HashMap-quizData;
//以下行出现异常!!
尝试{quizData=(HashMap)ois.readObject();}catch(ClassNotFoundException错误){throw error;}
问答游戏;
if((int)quizData.get(“版本”)==0){
测验=新测验((字符串)quizData.get(“名称”),
(字符串)quizData.get(“desc”),
(字符串)quizData.get(“timelimitType”),
(长)quizData.get(“时限”);
for(String serializedQuestionData:(String[])quizData.get(“questions”))
quick.addQuestion(Question.deserialize(serializedQuestionData));
}否则{
抛出新的UnsupportedOperationException(“不支持的版本:\”“+quizData.get(“版本”)+“\”);
}
回访测验;
}
我能想到的唯一解释是,在读写对象流之间,有东西正在破坏对象流。“本地类”(4290774380558885855)中的serialVersionID是所有尝试与Java(tm)兼容的Java实现中的标准版本。Java.lang.Long
的源代码表示,自Java 1.0.2以来,该串行版本id没有改变
如果需要进一步的帮助,则需要提供一个SSCE,该SSCE涵盖序列化对象的创建和读取。问题在于,您正在使用
toString()
将字节数组输出流转换为字符串。toString()
方法仅使用平台默认编码来转换字节(完全不表示字符,但纯粹是二进制数据)转换为字符串。因此,这是一种有损操作,因为平台默认编码并没有为每个可能的字节都指定一个有效字符
不应使用字符串保存二进制数据。字符串包含字符。如果确实需要字符串,请使用十六进制或Base64编码器对字节数组进行编码。否则,只需使用字节数组保存二进制数据:
public static byte[] serialize(Quiz quiz) throws IOException{
...
ByteArrayOutputStream baos = new ByteArrayOutputStream();
...
return baos.toByteArray();
}
@SuppressWarnings("unchecked")
public static Quiz deserialize(byte[] serializedQuizData) throws IOException, ClassNotFoundException{
ByteArrayInputStream bais = new ByteArrayInputStream(serializedQuizData);
...
return quiz;
}