The metadata of a bean has its own properties with independent bean definitions. Some of these bean definitions are as follows:

• Class: This will be used to create a bean, and it is mandatory to mention a class name for which we are supposed to create a bean.
•  Name: If we want to define different aliases for the bean, then we use the name attribute, with the help of a separator, such as a comma (,) or semicolon (;). When we have XML-based configuration, we can use the name and/or id attribute as an identifier for a bean. A bean with an id attribute is preferred, because it is mapped with an actual XML ID element. 
• Constructor-arg: A constructor argument is used to inject dependencies by passing a parameter as an argument in a constructor, which we saw in Chapter 3, Dependency Injection with Spring. 
• Properties: We can directly pass properties with key-value pairs in a Spring bean for injecting. This is useful sometimes if we need to pass certain fixed values to a bean.
• Autowiring mode: Autowiring can be used to reduce the use of properties and constructor arguments. To enable autowiring mode, we need to use the autowire attribute in a Spring bean. Attributes can have values such as byName, byType, and constructor.
• Lazy initialization mode: By default, a Spring bean is created with a singleton scope, which initializes all the properties in eager mode. If a bean is defined with lazy mode, then an IOC container creates a bean instance the first time the request comes, rather than during the startup process.
• Initialization method: Spring initialization works after all the properties are set by an IOC container. In XML-based configuration, we can define an init method by defining an init-method attribute. The init method should be void, and without arguments. A @PostConstruct annotation can be used for initializing methods.
• Destruction method: On completion of a bean lifecycle, if we have to close resources or want to perform actions before destruction of a bean, we can use the destroy-method attribute of a bean in XML configuration. The @PreDestroy annotation is also used instead of the XML attribute.

The following configuration file contains different types of bean definition syntax and for that, the application-context.xml file could be:

<?xml version="1.0" encoding="UTF-8"?>
<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.xsd">

       
   <!-- A simple bean definition with ID and Class Name-->
   <bean id = "..." class = "...">
      <!-- Bean configuration and properties like constructor-arg -->
   </bean>
   
   <!-- Bean definition using Name attribute instead of ID attribute -->
   <bean name = "..." class = "...">
      <!-- Bean configuration and properties like constructor-arg -->
   </bean>
   
   <!-- Ban definition with constructor arguments -->
   <bean id="..." class="...">
        <constructor-arg ref="..."/>
        <constructor-arg ref="..."/>
   </bean>
   
   <!-- Ban definition for autowiring using byName mode -->
   <bean id="..." class="..." autowire="byName">
   <!-- Bean configuration and properties like constructor-arg -->
   </bean>
   
   <!-- Ban definition for defining scope -->
   <bean id="..." class="..." scope="prototype">
   <!-- Bean configuration and properties like constructor-arg -->
   </bean> 
       
   <!-- Ban definition with lazy initialization mode -->
   <bean id = "..." class = "..." lazy-init = "true">
      <!-- Bean configuration and properties like constructor-arg -->
   </bean>
 
   <!-- Bean definition which has initialization method -->
   <bean id = "..." class = "..." init-method = "init">
       <!-- Bean configuration and properties like constructor-arg -->
   </bean>
 
   <!-- Bean definition which has destruction method -->
   <bean id = "..." class = "..." destroy-method = "destroy">
       <!-- Bean configuration and properties like constructor-arg -->
   </bean>
    
</beans>