问题
运行项目的后端代码，出现如下错误：
即：
org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘signInController’: Injection of resource dependencies failed;
nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name ‘signInService’: Bean with name ‘signInService’ has been injected into other beans [signInService] in its raw version as part of a circular reference, but has eventually been wrapped.
This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using ‘getBeanNamesOfType’ with the ‘allowEagerInit’ flag turned off, for example.
解决
可以看到“signInService”、“circular reference”，说明应该是signInService的调用出现了问题，出现了“自己调用自己”的情况。再仔细看看SignInServiceImpl，发现它调用了自己的接口层SignInService，所以出错了。
收获
遇到问题莫要慌，仔细看看问题，看看它在说啥，静下心来就能解决啦~向雅雯姐比心?( ????` )