- Cacheable Key Generator
- Spring Cacheable Keygenerator Example
- Cacheable Key Generator Example
- Spring Cacheable Key Generator Example For Kids
- Serial Key Generator
@FunctionalInterface public interface KeyGenerator Cache key generator. Used for creating a key based on the given method (used as context) and its parameters. (Object target, Method method, Object. Params) Generate a key.
From the spring documentation :
Spring cache abstraction is broken, as it doesn’t account for hash collisions, i.e. Given below signature: @Cacheable('myCache') int a(int a, String s) a(1, “FB”) will hash to the same key as a(1, “Ea”), when using the default key generator. The issue is that the cache abstraction doesn’t take advantage of equality test. This allows for customizing the strategy for cache key generation, per Spring's KeyGenerator SPI. Normally, @EnableCaching will configure Spring's SimpleKeyGenerator for this purpose, but when implementing CachingConfigurer, a key generator must be provided explicitly. Aug 23, 2018 We are also going to cover the option to create a custom key generator with Spring Cache. Spring Cache API uses a simple KeyGenerator for generating a key to store caching data. The default key generators for Spring Cache SimpleKeyGenerator.This default implementation uses the method parameters to generate the key. Here is the high-level overview for the default key generation algorithm.
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Update: Current Spring cache implementation uses all method parameters as the cache key if not specified otherwise. If you want to use selected keys, refer to Arjan’s answer which uses SpEL list
{#isbn, #includeUsed}
which is the simplest way to create unique keys.From Spring Documentation
The default key generation strategy changed with the release of Spring
4.0. Earlier versions of Spring used a key generation strategy that, for multiple key parameters, only considered the hashCode() of
parameters and not equals(); this could cause unexpected key
collisions (see SPR-10237 for background). The new
‘SimpleKeyGenerator’ uses a compound key for such scenarios.
4.0. Earlier versions of Spring used a key generation strategy that, for multiple key parameters, only considered the hashCode() of
parameters and not equals(); this could cause unexpected key
collisions (see SPR-10237 for background). The new
‘SimpleKeyGenerator’ uses a compound key for such scenarios.
Cacheable Key Generator
Before Spring 4.0
Nov 10, 2011 How to Generate A Public/Private SSH Key Linux By Damien – Posted on Nov 10, 2011 Nov 18, 2011 in Linux If you are using SSH frequently to connect to a remote host, one of the way to secure the connection is to use a public/private SSH key so no password is transmitted over the network and it can prevent against brute force attack.
Spring Cacheable Keygenerator Example
I suggest you to concat the values of the parameters in Spel expression with something like
key='#checkWarehouse.toString() + #isbn.toString()')
, I believe this should work as org.springframework.cache.interceptor.ExpressionEvaluator returns Object, which is later used as the key so you don’t have to provide an int
in your SPEL expression.As for the hash code with a high collision probability – you can’t use it as the key.
Someone in this thread has suggested to use
T(java.util.Objects).hash(#p0,#p1, #p2)
but it WILL NOT WORK and this approach is easy to break, for example I’ve used the data from SPR-9377 :Both lines print -636517714 on my environment.
P.S. Actually in the reference documentation we have
I think that this example is WRONG and misleading and should be removed from the documentation, as the keys should be unique.
It seems the hungarian translation of gnupg is in a horrible state. Key generation failed you do not have the sslmanager featured.
P.P.S. also see https://jira.springsource.org/browse/SPR-9036 for some interesting ideas regarding the default key generation.
I’d like to add for the sake of correctness and as an entertaining fact that using a secure cryptographic hash function like SHA256, due to the properties of such function IS possible for this task, but to compute it every time may be too expensive.
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After some limited testing with Spring 3.2, it seems one can use a SpEL list:
{.., .., ..}
. This can also include null
values. Spring passes the list as the key to the actual cache implementation. When using Ehcache, such will at some point invoke List#hashCode(), which takes all its items into account. (I am not sure if Ehcache only relies on the hash code.)I use this for a shared cache, in which I include the method name in the key as well, which the Spring default key generator does not include. This way I can easily wipe the (single) cache, without (too much…) risking matching keys for different methods. Like:
Of course, if many methods need this and you’re always using all parameters for your key, then one can also define a custom key generator that includes the class and method name:
…with:
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Cacheable Key Generator Example
You can use a Spring-EL expression, for eg on JDK 1.7:
Spring Cacheable Key Generator Example For Kids
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This will work
@Cacheable(value=”bookCache”, key=”#checkwarehouse.toString().append(#isbn.toString())”)
Serial Key Generator
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