Java：序列化外部（最终）字段

Question

我有一个类PasswordEncryptor，它使用org.jasypt.util.password.StrongPasswordEncryptor作为其中一个字段，因为我试图使应用程序“可群集”所有类都需要序列化以进行会话复制，但每当PasswordEncryptor访问1}}我遇到以下异常：

Caused by: java.io.NotSerializableException: org.jasypt.util.password.StrongPasswordEncryptor
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:891)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1063)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:1019)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:885)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteFields(RiverMarshaller.java:1063)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:1019)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:885)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:680)
    at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:62)
    at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:119)
    at org.jboss.as.clustering.SimpleMarshalledValue.getBytes(SimpleMarshalledValue.java:74)
    at org.jboss.as.clustering.SimpleMarshalledValue.writeObject(SimpleMarshalledValue.java:172)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.6.0_34]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) [rt.jar:1.6.0_34]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.6.0_34]
    at java.lang.reflect.Method.invoke(Method.java:622) [rt.jar:1.6.0_34]
    at org.jboss.marshalling.reflect.SerializableClass.callWriteObject(SerializableClass.java:175)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteSerializableObject(RiverMarshaller.java:1007)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:885)
    at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:62)
    at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:119)
    at org.infinispan.marshall.MarshallUtil.marshallMap(MarshallUtil.java:60)
    at org.infinispan.marshall.exts.MapExternalizer.writeObject(MapExternalizer.java:63)
    at org.infinispan.marshall.exts.MapExternalizer.writeObject(MapExternalizer.java:47)
    at org.infinispan.marshall.jboss.ExternalizerTable$ExternalizerAdapter.writeObject(ExternalizerTable.java:406)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:145)
    at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:62)
    at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:119)
    at org.infinispan.atomic.AtomicHashMap$Externalizer.writeObject(AtomicHashMap.java:229)
    at org.infinispan.atomic.AtomicHashMap$Externalizer.writeObject(AtomicHashMap.java:226)
    at org.infinispan.marshall.jboss.ExternalizerTable$ExternalizerAdapter.writeObject(ExternalizerTable.java:406)
    at org.jboss.marshalling.river.RiverMarshaller.doWriteObject(RiverMarshaller.java:145)
    at org.jboss.marshalling.AbstractObjectOutput.writeObject(AbstractObjectOutput.java:62)
    at org.jboss.marshalling.AbstractMarshaller.writeObject(AbstractMarshaller.java:119)
    at org.infinispan.marshall.jboss.AbstractJBossMarshaller.objectToObjectStream(AbstractJBossMarshaller.java:86)
    at org.infinispan.marshall.VersionAwareMarshaller.objectToObjectStream(VersionAwareMarshaller.java:151)
    at org.infinispan.marshall.AbstractDelegatingMarshaller.objectToObjectStream(AbstractDelegatingMarshaller.java:44)
    at org.infinispan.marshall.MarshalledValue.serialize0(MarshalledValue.java:119)
    ... 117 more
Caused by: an exception which occurred:
    in field spe
    in field bean
    in object java.util.HashMap@b629b463
    in object org.jboss.as.clustering.SimpleMarshalledValue@b629b463
    in object org.infinispan.util.FastCopyHashMap@43ad73a2
    in object org.infinispan.atomic.AtomicHashMap@4fd181fe
    in object org.infinispan.marshall.MarshalledValue@4fd181fe
    in object org.infinispan.commands.write.PutKeyValueCommand@ce32d716
    in object org.infinispan.commands.tx.PrepareCommand@293098b

我已尝试将字段标记为transient，如下所示：

import java.io.Serializable;

import org.jasypt.util.password.StrongPasswordEncryptor;

public class PasswordEncryptor implements Serializable {

    private static final long serialVersionUID = 1L;

    //Need to mark transient as its not serializable
    private transient StrongPasswordEncryptor spe = new StrongPasswordEncryptor();

    public String encrypt(String password){
        return spe.encryptPassword(password);
    }

    public boolean isPasswordCorrect(String enteredPassword, String passwordHash){
        return spe.checkPassword(enteredPassword, passwordHash);
    }

}

我不能使用包装器来继承StrongPasswordEncryptor，因为它是最终的

其他任何方法吗？ （最好不引入任何其他库）

Answer 1

从Infinispan的角度来看，控制类序列化的最佳方法，特别是当类是最终的或者您无法修改类时，最好的方法是为要序列化的类提供自己的Infinispan Externalizer。 。 Infinispan的用户指南包含有关how to Plug Infinispan with User-Defined Externalizers的完整章节，解释了它的优点，包括减少有效负载，更快的序列化以及无法修改要序列化的类时的问题。除了文档中的示例之外，Infinispan source code (ASL2)包含大量的Externalizer示例，可以满足您的需求。

更具体地说，PasswordEncryptor的Externalizer不需要在writeObject和readObject中编写任何内容，只需要实例化PasswordEncryptor。

Answer 2

您需要将字段标记为transient，就像您已经完成的那样。然后，您必须手动序列化该类的单个属性。这将是这样的：

 private void writeObject(ObjectOutputStream os){
   try{
    os.defaultWriteObject();
    os.writeChars(spe.encryptPassword("your password"));
   }
  catch (Exception e){
    e.printStackTrace();
  }
}

Answer 3

由于您使用零参数构造函数创建StrongPasswordEncryptor，因此您不需要任何其他数据来创建它。它没有你需要保存的状态，所以根本不需要序列化它。在反序列化后简单地重新创建它是安全的。

标记transient是正确的做法。

但是，反序列化对象中的瞬态字段为空。

您可以按照the Serializable documentation：

中的说明提供readObject方法

private transient StrongPasswordEncryptor spe = new StrongPasswordEncryptor();

/**
 *  Automatically called when this object is deserialized.
 */
private void readObject(ObjectInputStream in)
throws IOException,
       ClassNotFoundException {
    in.defaultReadObject();
    spe = new StrongPasswordEncryptor();
}

另一个选择是使字段瞬态并懒惰地初始化它：

private transient StrongPasswordEncryptor spe;

/**
 * Returns this object's StrongPasswordEncryptor, creating it
 * if necessary.
 */
private StrongPasswordEncryptor getEncryptor() {
    if (spe == null) {
        spe = new StrongPasswordEncryptor();
    }
    return spe;
}

public String encrypt(String password){
    return getEncryptor().encryptPassword(password);
}

public boolean isPasswordCorrect(String enteredPassword, String passwordHash){
    return getEncryptor().checkPassword(enteredPassword, passwordHash);
}