java - CDI:为什么我的 transient 字段被序列化？

Question

通过 CDI (Weld)，我为不可序列化的类实现了生产者方法。如果生产者被序列化并且字段 NonSerializedObject 消失，我会重新初始化一个 NonSerializedObject:

@SessionScoped
public class NonSerializableObjectProducer implements Serializable {

/** UUID */
private static final long serialVersionUID = -436472364723647647367L;

/** my transient non serializbale object */
private transient NonSerializableObject nonSerializableObject;

@SessionScoped
@Produces
protected NonSerializableObject produceNonSerializableObject() {
    if (nonSerializableObject == null) {
       // reinitialize object and set it
       // nonSerializableObject = ...
    }
    return nonSerializableObject;
}

我注入(inject)一个 NonSerializedObject，如下所示:

@SessionScoped
public class UseSerializableObject implements Serializable {

    private static final long serialVersionUID = 62378785678643784689L;

    @Inject
    private transient NonSerializableObject nonSerializableObject;

    public void doSomething() {
        nonSerializableObject.go();
    }
}

当我的应用服务器(Tomcat 7)重新部署时出现以下异常:

Sep 22, 2014 4:41:58 PM org.apache.catalina.session.StandardSession writeObject
WARNING: Cannot serialize session attribute WELD_S#5 for session 4694BB90FF1BBD8
java.io.NotSerializableException: com.MemberOfNonSerializableObject 
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1181)

因此，我的 NonSerializedObject 的成员变量被序列化。为什么？我宣布一切都是短暂的!

Answer 1

你的方法:

@SessionScoped
@Produces
protected NonSerializableObject produceNonSerializableObject() {}

生成@SessionScoped对象，该对象不可序列化。所有 @RequestScoped、@SessionScoped 和 @ApplicationScoped bean 都必须是可序列化的。

如果您从生产者方法中删除@SessionScoped，它就会起作用。