Defining the same Spring bean twice with same name

Question

Is having two definition for a bean (with same name and class) valid in Spring IOC ?

I am having two bean definition files included in web.xml. See the sample below.

Answer 1

I know it is very very late to reply, But sill want to add something...

It valid as long as you are defining two bean definitions with same id of same bean on two different spring configuration files. And you are importing one configuration file into another (kind of merging), does not matter how you importing (kind of merging). The later one or the last one bean definition will be override by the first one(s).

package com.demo.bean;
public class TestBean {
    private String message;
    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
}

e.g # 1

spring-config1.xml

spring-config2.xml

<

    

e.g # 2

spring-config1.xml

spring-config1.xml

web.xml

    org.springframework.web.context.ContextLoaderListener


    contextConfigLocation
    
        /WEB-INF/spring-config1.xml,
        /WEB-INF/spring-config2.xml
    

But if you are defining the two bean definitions with same bean id of same bean in same file you will find spring application start up failed. Spring would not let you define multiple bean definitions of same bean with same name in the same spring configuration file.

e.g # 3 spring-config3.xml

Error :

ERROR ContextLoader:331 - Context initialization failed
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Bean name 'testbean' is already used in this  element
Offending resource:  resource [/spring-config3.xml]

    at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:70)
    at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:85)
    at org.springframework.beans.factory.parsing.ReaderContext.error(ReaderContext.java:80)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.error(BeanDefinitionParserDelegate.java:316)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.checkNameUniqueness(BeanDefinitionParserDelegate.java:525)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:471)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseBeanDefinitionElement(BeanDefinitionParserDelegate.java:443)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.processBeanDefinition(DefaultBeanDefinitionDocumentReader.java:314)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseDefaultElement(DefaultBeanDefinitionDocumentReader.java:205)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:184)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:141)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:110)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:508)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:391)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:335)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:303)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:180)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:216)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:187)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
    at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:540)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:454)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4716)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5178)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:152)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1403)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1393)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)