解决：SpringBoot中注入StringRedisTemplate异常

在写一个商城项目中使用了StringRedisTemplate，结果测试启动时报错了：

BeanCreationException: Error creating bean with name 'userController': Injection of resource dependencies failed，

BeanNotOfRequiredTypeException: Bean named 'redisTemplate' is expected to be of type 'org.springframework.data.redis.core.StringRedisTemplate' but was actually of type 'org.springframework.data.redis.core.RedisTemplate'

翻译如下：

BeanCreationException：没有找到对应的bean，注入依赖资源项失败

BeanNotOfRequiredTypeException：名为“redisTemplate”的Bean应为“org.springframework.data.redis.core.StringRedisTemplate”类型，但实际为“org.springframework.data.redis.core.redisTemplate”类型。这个就很奇怪，我并没有用到redisTemplate的依赖，也不可能注入出错

详细错误日志

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'userController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'redisTemplate' is expected to be of type 'org.springframework.data.redis.core.StringRedisTemplate' but was actually of type 'org.springframework.data.redis.core.RedisTemplate'
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:324) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1411) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:592) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:849) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at com.czxy.CGWebServiceApplication.main(CGWebServiceApplication.java:16) [classes/:na]
Caused by: org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'redisTemplate' is expected to be of type 'org.springframework.data.redis.core.StringRedisTemplate' but was actually of type 'org.springframework.data.redis.core.RedisTemplate'
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:392) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:452) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:526) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:496) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:636) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:180) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:90) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]

后来我发现是这个Bean的名称问题，是因为名称问题导入注入失败？注入类型错误？

改成stringRedisTemplate，好了，原因@Resource是默认取字段名进行按照名称注入，下面有具体介绍

关于@Autowired和@Resource注解

更多关于自动装配的问题，这篇面试题里面有（二）Spring面试题

两个注解都可以完成依赖注入功能。
1.@Autowired：
  @Autowired ：默认是以byType按类型自动注入。
  @Autowired + @Qualifier(""名称"")：将按照名称自动注入
  
2.@Resource：
  @Resource() 如果没有指定name属性，当注解写在字段上时，默认取字段名进行按照名称注入，
  如果注解写在setter方法上默认取属性名进行注入。 
  当找不到与名称匹配的bean时才按照类型进行装配。但是需要注意的是，如果name属性一旦指定，就只会按照名称进行装配。
  @Resource(name="""")  将按照名称自动注入

我之前一直觉得面试题就是为了应付面试的，其实很多地方都有用到，不过是你没发现而已。