Java 无法加载BeanClassException：无法找到在 ServletContext 资源中定义的名称为“encryptionKey”的 bean 的类
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时间：2020-08-13 01:26:35 来源:igfitidea点击:
CannotLoadBeanClassException: Cannot find class for bean with name 'encryptionKey' defined in ServletContext resource
提问by Vettree
I want to get the dynamic class name based on what environment the application is running.
我想根据应用程序运行的环境获取动态类名。
Please help me out as I am totally stumped.
请帮助我，因为我完全被难住了。
In application-context.xml file, I have something like below
在 application-context.xml 文件中，我有如下内容
Application-context.xml
应用程序上下文.xml
<bean id="properyFilePlaceholderConfigurer" class="some class">
<property name="location">
<value>myxml.xml </value>
</property>
</bean>
<bean id="encryptionKey" class="${dynamic class}" />
<bean id="dataSource" class="some other class ">
<property name="targetDataSource" ref="targetDbDataSource"/>
<property name="username" value="${appdb.datasource.username}" />
<property name="password" value="${appdb.datasource.password}" />
<property name="encryptionKey" value=" encryptionKey "/>
</bean>
In myxml.xml
在 myxml.xml 中
For local
<item key="dynamic class" value="local.class " />
For Test
<item key="dynamic class" value="test.class " />
For Production
<item key="dynamic class" value="Production.class" />
It throws the error below
它抛出下面的错误
g.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [${some class }] for bean with name 'encryptionKey' defined in ServletContext resource [/WEB-INF/application-context.xml]; nested exception is java.lang.ClassNotFoundException: ${ some class }
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1160)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:581)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:206)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:493)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:348)
at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:251)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:190)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)
at com.ibm.ws.webcontainer.webapp.WebApp.notifyServletContextCreated(WebApp.java:1651)
at com.ibm.ws.webcontainer.webapp.WebAppImpl.initialize(WebAppImpl.java:410)
at com.ibm.ws.webcontainer.webapp.WebGroupImpl.addWebApplication(WebGroupImpl.java:88)
at com.ibm.ws.webcontainer.VirtualHostImpl.addWebApplication(VirtualHostImpl.java:169)
at com.ibm.ws.webcontainer.WSWebContainer.addWebApp(WSWebContainer.java:749)
at com.ibm.ws.webcontainer.WSWebContainer.addWebApplication(WSWebContainer.java:634)
at com.ibm.ws.webcontainer.component.WebContainerImpl.install(WebContainerImpl.java:422)
at com.ibm.ws.webcontainer.component.WebContainerImpl.start(WebContainerImpl.java:714)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:1154)
at com.ibm.ws.runtime.component.DeployedApplicationImpl.fireDeployedObjectStart(DeployedApplicationImpl.java:1369)
at com.ibm.ws.runtime.component.DeployedModuleImpl.start(DeployedModuleImpl.java:638)
at com.ibm.ws.runtime.component.DeployedApplicationImpl.start(DeployedApplicationImpl.java:967)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.startApplication(ApplicationMgrImpl.java:760)
at com.ibm.ws.runtime.component.ApplicationMgrImpl.start(ApplicationMgrImpl.java:2147)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:445)
at com.ibm.ws.runtime.component.CompositionUnitImpl.start(CompositionUnitImpl.java:123)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.start(CompositionUnitMgrImpl.java:388)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl.access0(CompositionUnitMgrImpl.java:116)
at com.ibm.ws.runtime.component.CompositionUnitMgrImpl$CUInitializer.run(CompositionUnitMgrImpl.java:994)
at com.ibm.wsspi.runtime.component.WsComponentImpl$_AsynchInitializer.run(WsComponentImpl.java:349)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1659)
Caused by: java.lang.ClassNotFoundException: ${ some class }
at java.net.URLClassLoader.findClass(URLClassLoader.java:434)
at com.ibm.ws.bootstrap.ExtClassLoader.findClass(ExtClassLoader.java:198)
at java.lang.ClassLoader.loadClassHelper(ClassLoader.java:665)
at java.lang.ClassLoader.loadClass(ClassLoader.java:644)
at com.ibm.ws.bootstrap.ExtClassLoader.loadClass(ExtClassLoader.java:113)
at java.lang.ClassLoader.loadClass(ClassLoader.java:627)
at com.ibm.ws.classloader.ProtectionClassLoader.loadClass(ProtectionClassLoader.java:62)
at com.ibm.ws.classloader.ProtectionClassLoader.loadClass(ProtectionClassLoader.java:58)
at com.ibm.ws.classloader.CompoundClassLoader.loadClass(CompoundClassLoader.java:565)
at java.lang.ClassLoader.loadClass(ClassLoader.java:627)
at com.ibm.ws.classloader.CompoundClassLoader.loadClass(CompoundClassLoader.java:565)
at java.lang.ClassLoader.loadClass(ClassLoader.java:627)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:230)
at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:371)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1157)
回答by Adam Arold
<bean id="properyFilePlaceholderConfigurer" class="some class">
<bean id="properyFilePlaceholderConfigurer" class="some class">
There is no some class(obviously). You need a valid class in that attribute.
没有some class（显然）。您需要该属性中的有效类。
回答by Mithun
If your not bound to use xml, I would suggest to use .properties file instead. Below code snippet works perfectly. This might be helpful for you. If you have different parameters/class names based on different environment, you can place one property file in each of the system. Spring will read the file from the system at runtime.
如果您不打算使用 xml，我建议您改用 .properties 文件。下面的代码片段完美运行。这可能对你有帮助。如果您根据不同的环境有不同的参数/类名，您可以在每个系统中放置一个属性文件。Spring 将在运行时从系统读取文件。
applicationContext.xml:
applicationContext.xml：
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd">
<bean id="propertyPlaceholderConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="location">
<value>file:C:\mybeans.properties</value>
</property>
</bean>
<bean id="mybean" class="${mybean}"></bean>
</beans>
mybean.properties:
mybean.properties：
mybean=com.main.BeanB
Testing program:
测试程序：
package com.main;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class TestApplication {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
System.out.println("Context loaded successfully");
MyBean bean = (MyBean) context.getBean("mybean");
bean.show();
((ClassPathXmlApplicationContext)context).close();
}
}
Bean classes:
豆类：
package com.main;
public abstract class MyBean {
abstract public void show();
}
package com.main;
public class BeanA extends MyBean{
public void show(){
System.out.println("I am in Bean A");
}
}
package com.main;
public class BeanB extends MyBean{
public void show(){
System.out.println("I am in Bean B");
}
}
