现象

本地IDE使用redis+ehcache缓存时，读取缓存抛出如下异常。明明是用一个类型，却发生A cannot be cast to A的ClassCastException的异常，实在是令人摸不着头脑。

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java.lang.ClassCastException: com.cardinfolink.saber.marketing.model.BenefitRecord cannot be cast to com.cardinfolink.saber.marketing.model.BenefitRecord

分析

stackoverflow

This is a known limitation of Devtools. When the cache entry is deserialized, the object is not attached to the proper classloader.

There are various ways you can fix this issue:

1. Disable cache when you’re running your application in development
2. Use a different cache manager (if you’re using Spring Boot 1.3, you could force a simple cache manager using the spring.cache.type property in application-dev.properties and enable the dev profile in your IDE)
3. Configure memcached (and things that are cached) to run in the application classloader. I wouldn’t recommend that option since the two first above are much easier to implement

当使用SpringBoot的DevTools用于热加载时，首先类加载器为A,对象被序列化到缓存。修改代码导致热加载后，DevTools重新创建了类加载器B。然后出现错误的类加载器加载对象导致A cannot be cast to A的异常。

解决

最简单无脑的方式就是删除DevTools的依赖。

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<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-devtools</artifactId>
</dependency>