The @Required
annotation is used to make sure a particular property has been set. If you are migrate your existing project to Spring framework or have your own @Required
-style annotation for whatever reasons, Spring is allow you to define your custom @Required-style annotation, which is equivalent to @Required annotation.
In this example, you will create a custom @Required-style annotation named @Mandatory, which is equivalent to@Required annotation.
1. Create the @Mandatory interface
package com.mkyong.common;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public
@interface Mandatory {}
2. Apply it to a property
package com.mkyong.common;
public class Customer {
private Person person;
private int type;
private String action;
@Mandatory
public void setPerson(Person person) {
this.person = person;
}
//getter and setter methods
}
3. Register it
Include your new @Mandatory
annotation in ‘RequiredAnnotationBeanPostProcessor
’ class.
<?xml version="1.0"?>`
<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">
<property name="requiredAnnotationType" value="com.mkyong.common.Mandatory" />
</bean>
<bean id="CustomerBean" class="com.mkyong.common.Customer">
<property name="action" value="buy" />
<property name="type" value="1" />
</bean>
</beans>
4. Done
Done, you just created a new custom @Required-style
annotation named @Mandatory
, which is equivalent to `@Required`` annotation.