Spring’s dependency checking in bean configuration file is used to make sure all properties of a certain types (primitive, collection or object) have been set. In most scenarios, you just need to make sure a particular property has been set, but not all properties..

For this case, you need @Required annotation, see following example :

@Required example

A Customer object, apply @Required in setPerson() method to make sure the person property has been set.

package com.mkyong.common;

import org.springframework.beans.factory.annotation.Required;

public class Customer
{
private Person person;
private int type;
private String action; public Person getPerson() {
return person;
}
@Required
public void setPerson(Person person) {
this.person = person;
}
}

Simply apply the @Required annotation will not enforce the property checking, you also need to register an RequiredAnnotationBeanPostProcessor to aware of the @Required annotation in bean configuration file.

The RequiredAnnotationBeanPostProcessor can be enabled in two ways.

1. Include <context:annotation-config />

Add Spring context and <context:annotation-config /> in bean configuration file.

<beans
...
xmlns:context="http://www.springframework.org/schema/context"
...
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd">
...
<context:annotation-config />
...
</beans>

Full example,

<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-2.5.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config /> <bean id="CustomerBean" class="com.mkyong.common.Customer">
<property name="action" value="buy" />
<property name="type" value="1" />
</bean> <bean id="PersonBean" class="com.mkyong.common.Person">
<property name="name" value="mkyong" />
<property name="address" value="address ABC" />
<property name="age" value="29" />
</bean> </beans>

2. Include RequiredAnnotationBeanPostProcessor

Include ‘RequiredAnnotationBeanPostProcessor’ directly in bean configuration file.

<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd"> <bean
class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/> <bean id="CustomerBean" class="com.mkyong.common.Customer">
<property name="action" value="buy" />
<property name="type" value="1" />
</bean> <bean id="PersonBean" class="com.mkyong.common.Person">
<property name="name" value="mkyong" />
<property name="address" value="address ABC" />
<property name="age" value="29" />
</bean> </beans>

If you run it , the following error message will be throw, because person property is unset.

org.springframework.beans.factory.BeanInitializationException:
Property 'person' is required for bean 'CustomerBean'

Conclusion

Try @Required annotation, it is more flexible than dependency checking in XML file, because it can apply to a particular property only.

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