在本周早些时候，我想计算可序列化类的serialVersionUID ，以便可以覆盖其toString方法而不会破坏所有内容。

我遇到了Frank Kim的博客文章 ，该文章建议使用JDK附带的serialver工具。

我创建了一个Maven小项目来在一个非常简单的类上测试该工具：

import java.io.Serializable;public class SerialiseMe implements Serializable
{}

如果我们将该类编译为一个JAR，然后运行serialver工具，则会看到以下输出：

$ serialver -classpath target/serialiser-0.0.1-SNAPSHOT.jar SerialiseMe
SerialiseMe:    static final long serialVersionUID = -6060222249255158490L;

我想快速确认我可以使用该值对这个类进行序列化和反序列化，因此我编写了以下代码来对该类进行序列化（当它没有串行版本的UID时）：

public class Serialiser
{public static void main( String[] args ) throws IOException, ClassNotFoundException{ByteArrayOutputStream bout = new ByteArrayOutputStream(  );ObjectOutputStream oout = new ObjectOutputStream( bout );Object value = new SerialiseMe();oout.writeObject( value );oout.close();byte[] bytes = bout.toByteArray();FileOutputStream fileOuputStream = new FileOutputStream("/tmp/foo.txt");fileOuputStream.write(bytes);fileOuputStream.close();}
}

完成之后，我编写了以下代码来反序列化文件：

public class Deserialiser
{public static void main( String[] args ) throws IOException, ClassNotFoundException{FileInputStream fileInputStream = new FileInputStream( new File( "/tmp/foo.txt" ) );byte[] bytes = IOUtils.toByteArray( fileInputStream );ByteArrayInputStream in = new ByteArrayInputStream( bytes, 0, bytes.length );ObjectInputStream oin = new ObjectInputStream( in );Object object = oin.readObject();}
}

我将串行版本的UID插入到该类中，并能够正确地反序列化它。 我尝试更改一个数字只是为了检查它是否会炸毁，并且确实做到了：

import java.io.Serializable;public class SerialiseMe implements Serializable
{static final long serialVersionUID = -6060222249255158491L;
}

Exception in thread "main" java.io.InvalidClassException: SerialiseMe; local class incompatible: stream classdesc serialVersionUID = -6060222249255158490, local class serialVersionUID = -6060222249255158491at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:604)at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1620)at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1515)at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1769)at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1348)at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)at Deserialiser.main(Deserialiser.java:18)at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:601)at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

serialver #ftw!

翻译自: https://www.javacodegeeks.com/2014/02/java-work-out-the-serialversionuid-of-a-class.html