blocks|key|3784098|text|不，不是。实例是有状态的。因此，您需要将其存储在线程本地，或者在每次加密/解密调用时获取一个新实例，或者将其包装在synchronized(cipher)块中。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3784099|在javadoc中，线程安全通常被称为"is+thread+safe“或"is++thread+safe”。Cipher并非如此，因此您不应该假设它是线程安全的。|3784100|entityMap|0|LINK|mutability|MUTABLE|url|https://www.google.com/search?q=%2522is%2520thread%2520safe%2522%2520site:https://docs.oracle.com/en/java/javase/16/docs/api|1|https://www.google.com/search?q=%2522is%2520not%2520thread%2520safe%2522%2520site:https://docs.oracle.com/en/java/javase/16/docs/api|2|https://docs.oracle.com/en/java/javase/16/docs/api/java.base/javax/crypto/Cipher.html^0|1L|K|0|1I|6|K|E|0|11|F|1|1I|6|2|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]|$9|12|A|13|1|14]|$9|15|A|16|1|17]]|E|$]]|$1|H|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]|P|$5|K|L|M|E|$N|Q]]|R|$5|K|L|M|E|$N|S]]]]

No, it isn't. The instance is stateful. So you need to store it threadlocal, or to obtain a new instance on every encrypt/decrypt call, or to wrap it in a <code>synchronized(cipher)</code> block.
Threadsafety is usually mentioned in javadocs as &quot;<a href="https://www.google.com/search?q=%22is%20thread%20safe%22%20site:https://docs.oracle.com/en/java/javase/16/docs/api" rel="nofollow noreferrer">is thread safe</a>&quot; or &quot;<a href="https://www.google.com/search?q=%22is%20not%20thread%20safe%22%20site:https://docs.oracle.com/en/java/javase/16/docs/api" rel="nofollow noreferrer">is not thread safe</a>&quot;. This is not the case for <a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/javax/crypto/Cipher.html" rel="nofollow noreferrer"><code>Cipher</code></a>, so you should not assume it to be threadsafe.

blocks|key|3784198|text|即使Cipher是线程安全的，从多个线程同时使用它也没有什么用处。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3784199|您输入和输出的字节(通过它的update和finish方法)是一个连续的流。这意味着，在另一端，它们必须以相同的顺序传递才有意义。如果只有一个线程这样做，这是最容易实现的。|offset|length|style|CODE|3784200|如果你使用多线程，你通常会想要在两次调用之间调用reset+--而且无论如何你都需要外部同步。|3784201|entityMap^0|0|E|6|L|6|0|O|5|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]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|K|$]]

Even if a Cipher was thread-safe, it would not really be useful to use it from multiple threads concurrently.

The bytes you put into and get out of the Cipher (via its <code>update</code> and <code>finish</code> methods) are a continuous stream. This means, on the other end, they have to be passed in the same order to make any sense. This is easiest to accomplish if you have only one thread doing this.

If you are using multiple threads, you usually would want to call <code>reset</code> between the calls - and then you will need external synchronization anyways.

blocks|key|1883844|text|我不会在没有同步的情况下使用来自多个线程的Cipher对象。当您查看API时，有一些方法只能通过更改内部状态才能工作，例如init()和update()。这使得它们隐式地不是线程安全的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1883845|entityMap^0|1P|6|1W|8|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

I wouldn't use Cipher objects from multiple threads without synchronization. When you look at the API, there are methods which can only work by changing internal state, such as <code>init()</code> and <code>update()</code>. That makes them implicitly non-thread-safe.

blocks|key|174523|text|密码不是线程安全的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|174524|如果你使用多线程来提高性能，并且不想做同步，你可以使用PooledPBEByteEncryptor+(http://www.jasypt.org/general-usage.html)，它有池化的加密器:+PooledPBEStringEncryptor，Jasypt。|offset|length|174525|如果同步对您来说没问题，并且您使用了Spring。您可以使用加密器(https://docs.spring.io/spring-security/site/docs/4.2.5.RELEASE/apidocs/org/springframework/security/crypto/encrypt/Encryptors.html)。它们在内部进行同步以访问密码。|174526|entityMap|0|LINK|mutability|MUTABLE|url|http://www.jasypt.org/general-usage.html|1|https://docs.spring.io/spring-security/site/docs/4.2.5.RELEASE/apidocs/org/springframework/security/crypto/encrypt/Encryptors.html^0|0|1F|14|0|0|Y|3M|1|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@$D|T|E|U|1|V]]|A|$]]|$1|F|3|G|5|6|7|W|8|@]|9|@$D|X|E|Y|1|Z]]|A|$]]|$1|H|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|I|$J|$5|K|L|M|A|$N|O]]|P|$5|K|L|M|A|$N|Q]]]]

Cipher is not thread safe. 

If you use multithreading for performance and don't want to do synchronization, you can use Jasypt (<a href="http://www.jasypt.org/general-usage.html" rel="nofollow noreferrer">http://www.jasypt.org/general-usage.html</a>) it has pooled encryptors: PooledPBEByteEncryptor, PooledPBEStringEncryptor.

If synchronization is ok for you and you use Spring. You can use Encryptors (<a href="https://docs.spring.io/spring-security/site/docs/4.2.5.RELEASE/apidocs/org/springframework/security/crypto/encrypt/Encryptors.html" rel="nofollow noreferrer">https://docs.spring.io/spring-security/site/docs/4.2.5.RELEASE/apidocs/org/springframework/security/crypto/encrypt/Encryptors.html</a>). They do synchronization internally to access Cipher.

Quite simply, can one instance of <code>javax.crypto.Cipher</code> (e.g. <code>Cipher.getInstance("RSA")</code>) be used from multiple threads, or do I need to stick multiple of them in a <code>ThreadLocal</code> (in my case)?

Is Cipher thread-safe?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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很简单，一个javax.crypto.Cipher实例(例如Cipher.getInstance("RSA"))是否可以从多个线程使用，或者我是否需要将多个线程放在一个ThreadLocal中(在我的例子中)？

问Cipher线程安全吗？
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