为什么在java中使用“transient”关键字?(复制)-Whyusethe`transient`keywordinjava?[duplicate]

29  

transient variables are never serialized in java.

暂态变量在java中从不序列化。

It marks a member variable not to be serialized when it is persisted to streams of bytes. When an object is transferred through the network, the object needs to be 'serialized'. Serialization converts the object state to serial bytes. Those bytes are sent over the network and the object is recreated from those bytes. Member variables marked by the java transient keyword are not transferred, they are lost intentionally.

当成员变量被持久化到字节流时，它标记为不被序列化。当一个对象通过网络传输时，该对象需要被“序列化”。序列化将对象状态转换为串行字节。这些字节通过网络发送，对象从这些字节中重新创建。由java临时关键字标记的成员变量没有被转移，它们是故意丢失的。

please have a look at what serialization is.? and also refer this

请看看序列化是什么。也请参考这

Example

例子

public class Foo implements Serializable
{
  private String saveMe;
  private transient String dontSaveMe;
  private transient String password;
  //...
}

In above example dontSaveMe & password are never get serialize as they are declare as a transient variables.

在上面的例子中，dontSaveMe和password永远不会被序列化，因为它们是作为瞬态变量声明的。

15  

And a short use - case:
Imagine exposing a User - Object via a public available webservice. You sure would like to expose things as nickname, online - state, maybe email or location. You definitly would not want to expose the password the user uses to login. Whilst this password could be a property of your User- object, it should not be serialized e.g. when serializing the object to a JSON - String for the webservice mentioned.

一个简短的用例:想象通过公共的web服务公开一个用户对象。你肯定会想公开一些东西，比如昵称、在线状态、电子邮件或位置。您肯定不想公开用户登录时使用的密码。虽然这个密码可能是您的用户对象的属性，但是它不应该被序列化，例如，当您为上面提到的webservice将对象序列化为JSON - String时。

6  

transient keyword suggests that the object should not be serialized, nor persisted. You can use it if you don't want to serialize heavy objects (such as Wrappers, for example, which can contain a lot of business logic).

瞬态关键字建议对象不应该被序列化，也不应该被持久化。如果不希望序列化重要对象(例如包装器，它可以包含很多业务逻辑)，可以使用它。

@Transient annotation suggests that the object should not be persisted (if you've been playing with Hibernate, for example), but it can be serialized.

@Transient注释建议对象不应该被持久化(例如，如果您正在运行Hibernate)，但是它可以被序列化。

I've included the annotation explanation, because I remember being confused by the two. :-)

我已经包含了注释解释，因为我记得我被这两个弄糊涂了。:-)

5  

• Transient keyword can only be applied to member variables.
  Applying it to method or local variable is compilation error.

  瞬态关键字只能应用于成员变量。将它应用于方法或局部变量是编译错误。

• The keyword transient in Java used to indicate that the variable
  should not be serialized. By default all the variables in the object are converted to persistent state. In some cases, you may want to
  avoid persisting some variables because you don’t have the necessity to transfer across the network. So, you can declare those variables
  as transient.

  Java中用于指示不应该序列化变量的关键字transient。默认情况下，对象中的所有变量都被转换为持久状态。在某些情况下，您可能希望避免持久化一些变量，因为您没有必要跨网络传输。你可以把这些变量声明为瞬态。

3  

transient is used to specify which properties of an object will not be saved or serialised. For example, when saving an object to a file, transient specifies which properties or attributes will not be saved to that file when that object is saved to a file.

瞬变用于指定一个对象的哪些属性不会被保存或序列化。例如，在将对象保存到文件中时，transient会指定在将对象保存到文件中时，不会将哪些属性或属性保存到该文件中。

When the object is re-created from the file, the value of that transient attribute (or private property) will not be re-created as it was never saved, or serialised to that file. In some cases, you may want to avoid persisting some of these private instance variables or attributes of an object, transient allows you to do that.

当对象从文件中重新创建时，该临时属性(或私有属性)的值将不会被重新创建，因为它从未被保存或序列化到该文件中。在某些情况下，您可能希望避免持久化这些私有实例变量或对象的属性，瞬态允许您这样做。