Some
times we need to perform some operatons while a bean is being created and
destroyed. Spring frame work provides support for call back methods to perform
these activities.
We can
achieve call back feature in two ways.
1. By implementing interfaces
InitializingBean, DisposableBean
2. By configuring in xml
In this
post, i am going to explain how to do call back functionality by configuring
xml file.
Step 1
: Create new
maven project “spring_tuorial”. Project structure looks like below.
Step 2
: Update
“pom.xml” file for maven dependencies.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>spring_tutorial</groupId> <artifactId>spring_tutorial</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <name>spring_tutorial</name> <description>spring_tutorial</description> <properties> <org.springframework-version>4.1.5.RELEASE</org.springframework-version> </properties> <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${org.springframework-version}</version> </dependency> </dependencies> </project>
Step
3: Create new
package “com.springtutorial.model” under “src/main/java”.
Step
4: Create
“Address” class under the package “com.springtutorial.model”.
package com.springtutorial.model; public class Address{ private String street; private String city; private String state; private String country; private String pin; public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } public String getCity() { return city; } public void setCity(String city) { this.city = city; } public String getState() { return state; } public void setState(String state) { this.state = state; } public String getCountry() { return country; } public void setCountry(String country) { this.country = country; } public String getPin() { return pin; } public void setPin(String pin) { this.pin = pin; } @Override public String toString() { StringBuilder builder = new StringBuilder(); builder.append("Address [street=").append(street).append(", city=").append(city) .append(", state=").append(state).append(", country=").append(country).append(", pin=") .append(pin).append("]"); return builder.toString(); } public void myDestroy() { System.out.println("Destroying Bean"); } public void myInit() { System.out.println("Properties set for bean"); } }
Step
5: Create
“Employee” class under the package “com.springtutorial.model”.
package com.springtutorial.model; public class Employee { private String firstName; private String lastName; private int id; private Address address; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public int getId() { return id; } public void setId(int id) { this.id = id; } public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } @Override public String toString() { StringBuilder builder = new StringBuilder(); builder.append("Employee [firstName=").append(firstName).append(", lastName=").append(lastName) .append(", id=").append(id).append(", address=").append(address).append("]"); return builder.toString(); } }
Step
6: Create
“spring.xml” file in “src/main/resources”.
spring.xml
<?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-3.0.xsd"> <bean id="employee1" class="com.springtutorial.model.Employee"> <property name="firstName" value="Hari Krishna" /> <property name="lastName" value="Gurram" /> <property name="id" value="553" /> <property name="address" ref="address"/> </bean> <bean id="address" class="com.springtutorial.model.Address" init-method="myInit" destroy-method="myDestroy"> <property name="street" value="Chowdeswari temple" /> <property name="city" value="Bangalore" /> <property name="state" value="Karnataka" /> <property name="country" value="India" /> <property name="pin" value="560037" /> </bean> </beans>
"spring.xml"
is used to assign unique IDs to different beans, to control the creation of
objects with different values. You have to make sure that “spring.xml” file is available
in CLASSPATH and use the same name in main application while creating
application context as shown in Main.java file.
init-method="myInit",
for the initialization callback, and destroy-method="myDestroy", for
the destroy callback. "myInit" and "myDestroy" are names of
instance methods in the Address class.
Step 7
: Create package
“com.springtutorial.main” under “src/main/java”.
Step 8
: Create Main
class under package “com.springtutorial.main”.
package com.springtutorial.main; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.springtutorial.model.Employee; public class Main { public static void main(String args[]) { ApplicationContext context = new ClassPathXmlApplicationContext("spring.xml"); Employee emp1 = (Employee) context.getBean("employee1"); System.out.println(emp1); ((ClassPathXmlApplicationContext) context).close(); } }
Step 9
: Run
Main.java,you will get output like below.
Mar 25, 2015 11:09:50 PM org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@1873a6: startup date [Wed Mar 25 23:09:50 IST 2015]; root of context hierarchy Mar 25, 2015 11:09:50 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions INFO: Loading XML bean definitions from class path resource [spring.xml] Properties set for bean Employee [firstName=Hari Krishna, lastName=Gurram, id=553, address=Address [street=Chowdeswari temple, city=Bangalore, state=Karnataka, country=India, pin=560037]] Mar 25, 2015 11:09:50 PM org.springframework.context.support.ClassPathXmlApplicationContext doClose INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@1873a6: startup date [Wed Mar 25 23:09:50 IST 2015]; root of context hierarchy Destroying Bean
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