報錯情況

1月 08, 2021 6:14:16 下午 org.springframework.context.support.AbstractApplicationContext refresh
警告: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [beanPostProcessorExample] for bean with name 'helloWorld' defined in class path resource [Beans.xml]; nested exception is java.lang.ClassNotFoundException: beanPostProcessorExample
Exception in thread "main" org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [beanPostProcessorExample] for bean with name 'helloWorld' defined in class path resource [Beans.xml]; nested exception is java.lang.ClassNotFoundException: beanPostProcessorExample
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1382)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:663)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:630)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1491)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1014)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:828)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:865)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:548)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
    at beanPostProcessorExample.MainApp.main(MainApp.java:7)
Caused by: java.lang.ClassNotFoundException: beanPostProcessorExample
 

    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:606)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:275)
    at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:437)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doResolveBeanClass(AbstractBeanFactory.java:1430)
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1374)
    ... 10 more
 

工程檔案

錯誤原因

在看到報錯資訊中

java.lang.ClassNotFoundException: beanPostProcessorExample

我查看了所有用到該包的程式碼，最後發現Beans.xml中的class屬性缺失類名

於是我補充了類名

執行成功！

結論：檢視錯誤資訊內造成原因（Caused by ...），如果是缺失類，可以檢視所有用到類的程式碼，新增即可。