So, let’s see Spring Bean Post Processors.<\/p>\n
![\"Spring](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2018\/07\/Spring-Bean-Post-Processors-01-1024x536.jpg\")
<\/a>Spring BeanPostProcessors – Latest Tutorial 2018<\/p><\/div>\n
2. Spring Bean Post Processors<\/h2>\n
The interface called BeanPostProcessors in Spring Framework is used for defining the callback methods which you can implement. So as to provide your own instantiation logic, dependencies resolution etc. Also, you are can implement some other custom logic after the initialization, configuration etc. of the Spring Beans by plugging more than Bean Post Processor implementations.<\/p>\n
Do you know Why Spring Framework is Popular<\/a><\/strong><\/p>\n You are allowed to configure more than one BeanPostProcessors interface and can control the order of execution of the BeanPostProcessors interface. This can be done by setting the order property given with the implementation of an Ordered interface by BeanPostProcessors.<\/p>\n The interface BeanPostProcessors operates on the instances of Bean. That is the Spring IoC container<\/strong> <\/a>instantiates bean instance after which the BeanPostProcessors interfaces do their work. The following is the example application with the steps using Eclipse IDE in which a class is created which implements BeanPostProcessors interface along with the two methods of it:<\/p>\n Read about Spring Batch Tutorial in detail<\/a><\/strong><\/p>\n The code for HelloWorld.java is as follow:<\/p>\n The example is a basic implementation of BeanPostProcessors which will print a Bean name before and after the initialization of the Bean. You have the free hand of writing any code before and after the initialization of the bean as you have the access on the object inside both the post processor methods.<\/p>\n The following is the MainApp.java file which has registerShutHook() declared on class AbstractApplicationContext:<\/p>\n Let’s discuss the Spring Bean Autowiring with Modes<\/strong><\/a><\/p>\n If you are done with the creation of the code and configuration files. After everything is working fine run the application you will see the following message as output:<\/p>\n BeforeInitialization: HelloWorld<\/strong><\/p>\n Bean is going through init.<\/strong><\/p>\n AfterInitialization: HelloWorld<\/strong><\/p>\n Your Message: Hello World!<\/strong><\/p>\n Bean will destroy now.<\/strong><\/p>\n So, this was all about Spring BeanPostProcessors. Hope you like our explanation.<\/p>\n Hence, in this session, we have learned Bean Post Processor in Spring Framework. This article had the implementation of the interface BeanPostProcessor and its two methods. Along with that, you had the working example using the Eclipse IDE. In our next tutorial, we will discuss\u00a0Spring-Bean Definition Inheritance<\/strong><\/a> in detail. Furthermore, if you have any query, feel free to ask in the comment section.<\/p>\n
\nThe methods you studied in Bean lifecycle init() and destroy() are different than the Spring BeanPostProcessors. The BeanPostProcessor in Spring Framework is common to all of the beans.<\/p>\n3. Spring BeanPostProcessors Example Using\u00a0 Eclipse IDE<\/h2>\n
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package com.example;\u00a0\r\npublic class HelloWorld {\r\n\u00a0\u00a0 private String message;\r\n\u00a0\u00a0 public void setMessage(String message){\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 this.message\u00a0 = message;\r\n\u00a0\u00a0 }\r\n\u00a0\u00a0 public void getMessage(){\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(\"Your Message : \" + message);\r\n\u00a0\u00a0 }\r\n\u00a0\u00a0 public void init(){\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(\"Bean is going through init.\");\r\n\u00a0\u00a0 }\r\n\u00a0\u00a0 public void destroy(){\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(\"Bean will destroy now.\");\r\n\u00a0\u00a0 }\r\n}<\/pre>\na. Following is the InitHelloWorld.java<\/strong><\/h4>\n
package com.example;\u00a0\r\nimport org.springframework.beans.factory.config.BeanPostProcessor;\r\nimport org.springframework.beans.BeansException;\r\npublic class InitHelloWorld implements BeanPostProcessor {\r\n\u00a0\u00a0 public Object postProcessBeforeInitialization(Object bean, String beanName)\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 throws BeansException {\u00a0\u00a0\u00a0\u00a0\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(\"BeforeInitialization : \" + beanName);\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 return bean;\u00a0 \/\/ you can return any other object as well\r\n\u00a0\u00a0 }\r\n\u00a0\u00a0 public Object postProcessAfterInitialization(Object bean, String beanName)\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 throws BeansException {\u00a0\u00a0\u00a0\u00a0\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 System.out.println(\"AfterInitialization : \" + beanName);\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 return bean;\u00a0 \/\/ you can return any other object as well\r\n\u00a0\u00a0 }\r\n}<\/pre>\npackage com.example;\u00a0\r\nimport org.springframework.context.support.AbstractApplicationContext;\r\nimport org.springframework.context.support.ClassPathXmlApplicationContext;\r\npublic class MainApp {\r\n\u00a0\u00a0 public static void main(String[] args) {\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 AbstractApplicationContext context = new ClassPathXmlApplicationContext(\"Beans.xml\");\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 HelloWorld obj = (HelloWorld) context.getBean(\"helloWorld\");\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 obj.getMessage();\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 context.registerShutdownHook();\r\n\u00a0\u00a0 }\r\n}<\/pre>\nb.\u00a0The configuration file for Beans.xml is as defined<\/h4>\n
<?xml version = \"1.0\" encoding = \"UTF-8\"?>\u00a0\r\n<beans xmlns = \"http:\/\/www.springframework.org\/schema\/beans\"\r\n \u00a0 xmlns:xsi = \"http:\/\/www.w3.org\/2001\/XMLSchema-instance\"\r\n\u00a0\u00a0 xsi:schemaLocation = \"http:\/\/www.springframework.org\/schema\/beans\r\n\u00a0\u00a0 http:\/\/www.springframework.org\/schema\/beans\/spring-beans-3.0.xsd\">\u00a0\r\n\u00a0\u00a0 <bean id = \"helloWorld\" class = \"com.example.HelloWorld\"\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 init-method = \"init\" destroy-method = \"destroy\">\r\n\u00a0\u00a0\u00a0\u00a0\u00a0 <property name = \"message\" value = \"Hello World!\"\/>\r\n\u00a0\u00a0 <\/bean>\u00a0\r\n\u00a0\u00a0 <bean class = \"com.example.InitHelloWorld\" \/>\u00a0\r\n<\/beans><\/pre>\n
4. Conclusion<\/h2>\n