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Examples
Spring MVC Framework List of Abbreviations List of Jars in Spring 3.0 Framework What is loose coupling in spring with example Dependency injection in Spring Framework with example What is Application Context in Spring Framework How to use ClassPathXmlApplicationContext in Spring Framework with Example How to use FileSystemXmlApplicationContext in Spring Framework with Example
Examples [cont'd]
How to use XmlWebApplicationContext in Spring Framework with Example Hello world example using spring bean configuration Spring bean wiring with constructor arguments example Passing bean as constructor arguments to another bean in Spring Framework What is Singleton with factory-method in Spring Framework with Example Singleton bean scope in Spring Framework with Example Prototype bean scope in Spring Framework with Example
Examples [cont'd]
Spring MVC request scoped bean with Example Spring MVC session scoped bean Example Init and destroy method in Spring Framework with Example Initializingbean and Disposablebean in Spring Framework with Example Default init and destroy method in Spring configuration file with Example How to inject property value in Spring Framework with Example Injecting bean references in spring framework with example
Examples [cont'd]
Inner beans in Spring Framework with Example Injecting property values using Spring's p namespace with Example How to use <set> in Spring configuration with Example How to use <list> in Spring configuration with Example How to use <map> element in Spring XML configuration with Example How to use <props> element in Spring XML configuration with Example How to set null value as property value in Spring framework with Example
Examples [cont'd]
How to use SpEL (Spring Expressions) in Spring XML configuration with Example Reference bean using SpEL in Spring XML configuration with Example Accessing Static members using T() Operator in Spring configuration with Example Spring Expression (SpEL) Arithmetic Operators Example Spring Expression (SpEL) Relational Operators Example Spring Expression (SpEL) Logical Operators Example Spring Expression (SpEL) Ternary and Elvis Operator with Example
Examples [cont'd]
Spring Expression (SpEL) Regular expression matches with Example How to use Collections with Spring Expression (SpEL) Example How to load properties file from classpath in Spring Framework with Example How to access system environment variables in Spring configuration with Example How to access system properties in spring configuration with example How to autowire properties in Spring framework using 'byName' with Example How to autowire properties in Spring framework using 'byType' with Example
Examples [cont'd]
How to autowire properties in Spring framework using 'constructor' with Example How to set default autowire type in Spring configuration with Example How to wire implicit and explicit beans to properties in Spring Framework with Example How to use @Autowired Annotation in Spring framework with Example How to use @Autowired with byName injection using @Qualifier in Spring Framework with Example How to use @Autowired Annotation with Constructors in Spring with Example @Autowired required property in Spring Framework with Example
Examples [cont'd]
How to create custom qualifier using Annotations in Spring framework with Example Example to use @Inject annotation of Java Dependency Injection with Spring How to use javax.inject.Provider in Java DI with Spring Example How to use @Named annotation of Java DI with Spring Example Custom Qualifier using @Qualifier annotation of Java Dependency Injection with Spring Example Injecting literal and bean values to properties using @Value annotation in Spring with Example How to create Annotated Beans in Spring using @Component and component-scan tag?
Examples [cont'd]
How to use component-scan with include-filter and exclude-filter in Spring with Example How to use component-scan with annotation filter in Spring with Example How to use component-scan with custom annotation filter in Spring with Example How to use component-scan with assignable to specific type in Spring with Example Component-scan with regular expression(regex) matches with class names filter in Spring with Example Configuring beans by @Configuration and @Bean of Java-based configuration in Spring with Example Injecting beans to properties using Java-based annotations in Spring with Example
Examples [cont'd]
Spring framework's Aspect Oriented Programming(AOP) with Example Spring's <aop:aspect> tag with after,before,after-returning,after-throwing and pointcut Example Spring AOP's pointcut expression using args() AspectJ Designator with Example Spring AOP's pointcut expression using @args() AspectJ Designator with Example Spring AOP's pointcut expression using execution() AspectJ Designator with Example Spring AOP's pointcut expression using this() AspectJ Designator with Example Spring AOP's pointcut expression using target() AspectJ Designator with Example
Examples [cont'd]
Spring AOP's pointcut expression using @target() AspectJ Designator with Example Spring AOP's pointcut expression using within() AspectJ Designator with Example Spring AOP's pointcut expression using @within() AspectJ Designator with Example Spring AOP's pointcut expression using @annotation() AspectJ Designator with Example Spring AOP's pointcut expression using bean() AspectJ Designator with Example Spring AOP's pointcut expression with logical operators with Example How to use <aop:around> in Spring with Example
Examples [cont'd]
How to use <aop:declare-parents> element in Spring Framework with Example How to use Annotation based AspectJ using <aop:aspectj-autoproxy> in Spring with Example Spring's AOP advise with Parameters using XML with Example Spring's @Aspect, @Pointcut, @Before, @After, @AfterReturning and @AfterThrowing Annotations Example How to use @DeclareParents annotation in Spring Framework with Example How to use JNDI DataSource provided by Tomcat in Spring using jee:jndi-lookup Example How to access ApplicationContext (Bean-Factory) of Spring in Web Servlet with Example
Examples [cont'd]
How to use connection pool datasource in spring framework using Apache's BasicDataSource with example How to use DriverManagerDataSource JDBC driver based Database Access with Spring Example How to use JdbcTemplate in spring using indexed parameters with example How to use NamedParameterJdbcTemplate in spring using named parameters with example How to use JdbcDaoSupport in Spring using JdbcTemplate with Example
What is Singleton with factory-method in Spring Framework with Example
7158 Views
Singleton 
Singleton Class allows the user to get only one instance not allow to create multiple objects. Only one object can create by the Singleton Classes.

In below example even scope is prototype but factory-method (getInstance) returns same instance from the application context.
Step.1 Start a Java Project with Spring Jars 
  1. Open Eclipse
  2. Click on menu New -> Others
  3. In wizards type "Java Project" and Select "Java Project"
  4. Click Next
  5. Enter project name as "SingletonFactoryMethodExample", then click Next
  6. Goto Libraries tab, then click on Add External JARs, then select Spring's 21 Framework Jars and commons-logging-1.1.jar.
  7. Click Finish.
Step.2 Project Explorer Preview 
FinancialConstants.java
package com.knowledgewalls;

public class FinancialConstants {
    public double PI = 3.14;
    private static FinancialConstants financialConstants = new FinancialConstants();
    
    private FinancialConstants(){}
    public static FinancialConstants getInstance(){
        return financialConstants;
    }
}
bean-configuration.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="financialConstants" class="com.knowledgewalls.FinancialConstants" factory-method="getInstance" scope="prototype" />
</beans>
RunMyProblem.java
package com.knowledgewalls;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class RunMyProgram {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("bean-configuration.xml");
        FinancialConstants financialConstants = (FinancialConstants) context.getBean("financialConstants");
        FinancialConstants financialConstants2 = (FinancialConstants) context.getBean("financialConstants");
        
        System.out.println(financialConstants.getInstance().hashCode());
        System.out.println(financialConstants.getInstance().PI);
        System.out.println(financialConstants2.getInstance().hashCode());
        
    }
}
Output 
2758093
3.14
2758093
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