在 MyBatis 3/Java 上从缓存反序列化对象时出现问题

发布于 2024-10-16 02:53:14 字数 1649 浏览 6 评论 0原文

所以我正在使用 MySQL/MyBatis3/Tomcat 进行一个业余项目。我目前正在致力于在 MyBatis 中打开缓存。当我第一次尝试打开缓存时，由于我的对象没有实现可序列化，所以出现了异常。因此，在使用我尝试缓存的对象实现 Serialized 之后；它看起来缓存得很好。

但;当我在同样的情况下第二次访问我的 servlet 时，对象映射器尝试从缓存中反序列化我的对象，我得到以下堆栈跟踪：

### Error querying database.  Cause: org.apache.ibatis.cache.CacheException: Error deserializing object.  Cause: java.lang.ClassNotFoundException: my.package.MyClass
### Cause: org.apache.ibatis.cache.CacheException: Error deserializing object.  Cause: java.lang.ClassNotFoundException: my.package.MyClass
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:8)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:77)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:69)
at org.apache.ibatis.binding.MapperMethod.executeForList(MapperMethod.java:85)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:65)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:38)
at $Proxy5.selectAllArgs(Unknown Source)

我不明白的另一件事是：

Serializable result;
try {
  ByteArrayInputStream bis = new ByteArrayInputStream((byte[]) value);
  ObjectInputStream ois = new ObjectInputStream(bis);

  // LINE THROWING EXCEPTION IN org.apache.ibatis.cache.decorators.SerializedCache
  result = (Serializable) ois.readObject();
  // -- -----------------------------------

  ois.close();
} catch (Exception e) {
  throw new CacheException("Error deserializing object.  Cause: " + e, e);
}
return result;

为什么它甚至试图首先加载类？它只需要转换为可序列化即可。值得注意的是，当我没有打开缓存时；一切都按预期进行。

原文

So I'm working on a side project using MySQL/MyBatis3/Tomcat. I'm currently working on turning on caching in MyBatis. When I first tried to turn on caching, I got exceptions due to the fact that my object didn't implement Serializable. So, after implementing Serializable with the object I was trying to cache; it appeared to cache fine.

But; when I hit my servlet a second time with the same situation, and the object mapper attempts to deserialize my object from the cache, I get the following stack trace:

### Error querying database.  Cause: org.apache.ibatis.cache.CacheException: Error deserializing object.  Cause: java.lang.ClassNotFoundException: my.package.MyClass
### Cause: org.apache.ibatis.cache.CacheException: Error deserializing object.  Cause: java.lang.ClassNotFoundException: my.package.MyClass
at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:8)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:77)
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:69)
at org.apache.ibatis.binding.MapperMethod.executeForList(MapperMethod.java:85)
at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:65)
at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:38)
at $Proxy5.selectAllArgs(Unknown Source)

The other thing I don't understand is this:

Serializable result;
try {
  ByteArrayInputStream bis = new ByteArrayInputStream((byte[]) value);
  ObjectInputStream ois = new ObjectInputStream(bis);

  // LINE THROWING EXCEPTION IN org.apache.ibatis.cache.decorators.SerializedCache
  result = (Serializable) ois.readObject();
  // -- -----------------------------------

  ois.close();
} catch (Exception e) {
  throw new CacheException("Error deserializing object.  Cause: " + e, e);
}
return result;

Why is it even trying to load the class to begin with? It just needs to cast to Serializable. Its worth noting that when I don't have caching turned on; everything works as expected.

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樱娆 2024-10-23 02:53:14

基本上，发生这种情况的原因是因为我在 Eclipse 中的项目设置不正确，这导致我的服务器启动时某些类不可用。基本上，我所做的就是将构建输出目录从“workspace/project/build”更改为“workspace/project/WebContent/WEB-INF/build”。我现在要阅读有关正确 servlet 部署的更多信息......

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