异常：java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType解决方案

1.先来看看异常日志 (java.lang.Class不能被转换为java.lang.reflect.ParameterizedType)

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘baseTestImpl’ defined in file [D:\workspace\jc-demo\gateway\target\classes\com\jc\gateway\test\base\BaseTestImpl.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.jc.gateway.test.base.BaseTestImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1303) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1197) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:845) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.boot.web.reactive.context.ReactiveWebServerApplicationContext.refresh(ReactiveWebServerApplicationContext.java:66) ~[spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:742) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:389) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:311) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1213) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1202) [spring-boot-2.1.6.RELEASE.jar:2.1.6.RELEASE]
at com.jc.gateway.GatewayApplication.main(GatewayApplication.java:17) [classes/:na]
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.jc.gateway.test.base.BaseTestImpl]: Constructor threw exception; nested exception is java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:184) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1295) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
… 17 common frames omitted
Caused by: java.lang.ClassCastException: java.lang.Class cannot be cast to java.lang.reflect.ParameterizedType
at com.jc.gateway.test.base.BaseTestImpl.(BaseTestImpl.java:24) ~[classes/:na]
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_301]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_301]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_301]
at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_301]
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:172) ~[spring-beans-5.1.8.RELEASE.jar:5.1.8.RELEASE]
… 19 common frames omitted

2.很明显错误指向BaseTestImpl.java:24，打断点检查

我用的是springboot+springcloud框架，启动main方法时BaseTestImpl构造器中反射类型转型失败异常，导致无法创建BaseTestImpl bean

3.解决方案如下（加入if条件构造器运行时）

    Class<V> vClass;

    public BaseTestImpl() {
        //获取泛型的class类型
        Type genericSuperclass = this.getClass().getGenericSuperclass();
        if(genericSuperclass instanceof ParameterizedType){
            Type[] actualTypeArguments = ((ParameterizedType) genericSuperclass).getActualTypeArguments();
            this.vClass = (Class<V>) actualTypeArguments[0];
        }
    }