blocks|key|1522507|text|如果您不打算序列化实例，请添加一个SuppressWarning。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522508|生成的序列ID可能有点危险。它表明您有意为其指定了序列号，并将其保存以进行序列化和反序列化。在更改类的较新版本的应用程序中，很容易忘记更新序列号。如果类字段已更改，则反序列化将失败。拥有一个SuppressWarning至少可以告诉代码的读者您不打算序列化这个类。|1522509|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

If you do not plan to serialize instances, add a SuppressWarning.

A generated serial ID can be a bit dangerous. It suggests that you intentionally gave it a serial number and that it is save to serialize and deserialize. It's easy to forget to update the serial number in a newer version of your application where your class is changed. Deserialization will fail if the class fields have been changed. Having a SuppressWarning at least tells the reader of your code that you did not intend to serialize this class.

blocks|key|1522554|text|我拒绝被Eclipse吓倒，让我的代码变得杂乱！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522555|我只是将Eclipse配置为不生成关于缺少serialVersionUID的警告。|1522556|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I refuse to be terrorized by Eclipse into adding clutter to my code!

I just configure Eclipse to not generate warnings on missing serialVersionUID.

blocks|key|1737831|text|感谢@+Steve+Jessop在这个问题上的回答。只有5行代码...这几乎不是什么麻烦。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1737832|我在这个类的上方添加了@SuppressWarnings("serial")。|offset|length|style|CODE|1737833|我还添加了这个方法：|1737834|private+void+writeObject(ObjectOutputStream+oos)+throws+IOException+{
+++throw+new+IOException("This+class+is+NOT+serializable.");
}|code-block|syntax|javascript|1737835|希望这就是史蒂夫的意思:)|1737836|entityMap^0|0|B|R|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@$D|U|E|V|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|X|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Thanks @ Steve Jessop for his answer on this. It was 5 lines of code... hardly a hassle.

I added <code>@SuppressWarnings("serial")</code> just above the class in question.

I also added this method:

<pre><code>private void writeObject(ObjectOutputStream oos) throws IOException {
 throw new IOException("This class is NOT serializable.");
}
</code></pre>

Hopefully that's what Steve meant :)

blocks|key|1522640|text|即使您知道这个对象将被序列化，也不需要生成serialVersionUID，因为java将自动为您生成它，并将自动跟踪更改，因此序列化将始终正常工作。只有当您知道自己在做什么(向后序列化兼容性、手动更改跟踪等)时，才应该生成它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522641|因此，我想说，在大多数情况下，抑制警告是最好和最安全的解决方案。|1522642|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Even if you know this object will be serialized there is no need to generate serialVersionUID because java will automatically generate it for you and will automatically keep track of changes so your serialization will always work just fine. You should generate it only if you know what you are doing (backward serialization compatibility, manual change tracking etc.)

So I would say suppressing the warning is the best and safest solution in most cases.

blocks|key|1737465|text|让Eclipse生成一个ID。快速而简单。警告是不容忽视的。如果您遇到对象/必须/需要序列化的情况，还可以省去很多麻烦。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1737466|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Let Eclipse generate an ID. Quick and easy. Warnings are not to be ignored. Also saves you lots of trouble should you ever come to the point where the object /has/ to be serialized.

blocks|key|1737726|text|如果省略了serialVersionUID，java将在编译时为类生成一个(每次编译都会改变)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1737727|在对对象进行反序列化时，反序列化对象的serialVersionUID将与jvm中的类的jvm进行比较。如果它们不同，则它们被认为是不兼容的，并抛出异常。例如，在升级程序和反序列化旧类之后，可能会发生这种情况。|1737728|我总是使用1L表示serialversionUID。它不会造成伤害(与生成的默认值相比)，并且它仍然保留了稍后通过递增id来破坏兼容性的选项。|1737729|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

If you leave out a serialVersionUID java will generate one for the class at compile time (it changes with every compilation).

When deserializing objects the serialVersionUID of the deserialized object is compared to that of the class in the jvm. If they are different they are considered incompatible and an Exception is thrown. This can happen for instance after upgrading your program and deserializing old classes.

I always use 1L for serialversionUID. It doesn't hurt (compared to the default generated) and it still leaves the option of breaking compatibility later by incrementing the id.

blocks|key|1737919|text|那得看情况。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1737920|如果您使用不同的编译器多次编译源代码，则编译后的代码可能具有不同的serializationIds，从而中断序列化。然后，您需要在代码中显式地坚持使用常量serializationId。它必须是静态的和最终的，并且每个类都是(不可继承的)。|1737921|但是，如果您总是使用特定的编译器编译代码，并且总是一次性将代码部署到所有虚拟机，那么您可能需要严格的版本检查，并希望确保任何时候只有一个版本的代码在运行，在这种情况下，您应该禁止显示警告。因此，如果VM没有成功部署，并且正在运行旧版本的代码，您可能会在序列化过程中遇到异常，而不是怪异的反序列化对象。这恰好是我的情况，我们曾经有一个非常非常大的集群，我们需要严格的版本检查来发现任何部署问题。|1737922|无论如何，您可能应该尽可能避免序列化，因为默认的序列化与协议缓冲区或节俭相比非常慢，并且不支持跨语言互操作性。|1737923|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

It depends.

If you use different compilers to compile your source code multiple times, your compiled code could have different serializationIds that will break the serialization. Then you need to stick to a constant serializationId explicitly in your code. It must be static and final and per class (not inheritable). 

However, if you always compile your code with a specific compiler and always deploy your code in one shot to all of your VMs, you probably need strict version checking and want to make sure that anytime there is only one version of you code running, in that case, you should just suppress the warning. So in case a VM is not deployed successfully and is running old version of your code, you probably expect an exception during serialization rather than quirk deserialized objects. This happens to be my case, we used to have a very very large cluster and we need strict version checking to find out any deployment issue.

Anyway, probably you should avoid serialization whenever possible since the default serialization is very slow compared to protocol buffers or thrift and does not support cross-language interoperability.

blocks|key|1522788|text|请点击此链接获取详细说明：http://technologiquepanorama.wordpress.com/2009/02/13/what-is-use-of-serialversiouid/|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1522789|entityMap|0|LINK|mutability|MUTABLE|url|http://technologiquepanorama.wordpress.com/2009/02/13/what-is-use-of-serialversiouid/^0|D|2D|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Please follow this link to get detailed explanation: <a href="http://technologiquepanorama.wordpress.com/2009/02/13/what-is-use-of-serialversiouid/" rel="nofollow noreferrer">http://technologiquepanorama.wordpress.com/2009/02/13/what-is-use-of-serialversiouid/</a>

blocks|key|1522965|text|如果您知道您的应用程序从不序列化内容，则在整个应用程序范围内禁止显示该警告。这可以使用javac命令行参数来完成：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522966|javac+-Xlint+-Xlint:-serial+*******|offset|length|style|CODE|1522967|这样，您将得到除“序列”之外的所有警告。IDE和像Maven/SBT/Gradle这样的构建工具可以很好地使用这些工具。|1522968|entityMap^0|0|0|Z|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

If you know your applications never serializes things, suppress the warning application-wide. This can be done using javac command line arguments:

<code>javac -Xlint -Xlint:-serial *******</code>

This way you will have all warnings except "serial". IDE-s and build tools like Maven/SBT/Gradle work fine with that.

I want to create a class that, for example, extends HttpServlet? My compiler warns me that my class should have a serialVersionUID. If I know that this object will never be serialized, should I define it or add an annotation to suppress those warnings?

What would you do and why?

Use the serialVersionUID or suppress warnings?

虚拟机

编译器

Eclipse

我想创建一个类，例如，扩展HttpServlet？我的编译器警告我我的类应该有一个serialVersionUID。如果我知道这个对象永远不会被序列化，我应该定义它还是添加注释来抑制这些警告？你会做什么?为什么？

问使用serialVersionUID还是禁止显示警告？
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问使用serialVersionUID还是禁止显示警告？
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