Question

我想根据应用程序运行的环境获取动态类名。

请帮助我，因为我完全被难倒了。

在application-context.xml文件中，我有类似下面的内容

应用程序的context.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>

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" />

它会抛出错误

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.access$500(CompositionUnitMgrImpl.java:116)
    at com.ibm.ws.runtime.component.CompositionUnitMgrImpl$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)

Answer 1

<bean id="properyFilePlaceholderConfigurer" class="some class">

没有some class（显然）。您需要该属性中的有效类。

Answer 2

如果您没有使用xml，我建议改用.properties文件。下面的代码片段完美无缺。这可能对你有所帮助。如果根据不同的环境有不同的参数/类名，则可以在每个系统中放置一个属性文件。 Spring将在运行时从系统中读取文件。

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=com.main.BeanB

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");
}
}

CannotLoadBeanClassException：无法在ServletContext资源中定义名称为“encryptionKey”的bean的类

2 个答案: