JAVA EE: Date Injection

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Friday, 10 August 2018

How to inject Date into bean property using Factory bean in Spring

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Overview: Injecting Date Properties with Factory Beans

In the Spring Framework, injecting primitive data types and strings into bean properties is straightforward. However, configuring non-trivial objects like java.util.Date directly through XML can be tricky because dates require parsing from formatted strings. A clean, robust way to handle this without hardcoded logic is by utilizing a FactoryBean (such as SimpleDateFormat with factory methods or custom factory bean implementations).

In this guide, you will learn how to configure and inject a java.util.Date object into a Spring bean property using factory bean mechanisms.

Why Use Factory Beans for Date Injection?

Working with complex object creation in Spring configuration brings several advantages:

Encapsulated Instantiation: Factory beans encapsulate complex parsing, custom formatting, and initialization logic away from consumer beans.
Clean XML Configuration: Instead of embedding conversion code across classes, date parsing is declared cleanly in configuration.
Reusability: Once configured, the resulting date bean or format factory can be injected across multiple beans in your application context.
Decoupled Architecture: Keeps domain and service beans free of parsing boilerplate and focused purely on core business logic.

Step-by-Step Implementation

Define Date Formatter Bean: Set up a date formatting bean (such as SimpleDateFormat) with the desired date pattern in XML.
Produce Date via Factory Method / FactoryBean: Invoke the parsing method using factory methods or a dedicated FactoryBean to produce the Date instance.
Inject into Target Bean: Reference the parsed date bean in your target bean's property definition:
<bean id="targetBean" class="com.example.Person"> <property name="dateOfBirth" ref="dateBean"/> </bean>
Run and Verify: Start the Spring context and verify that the target bean receives the correctly instantiated and formatted Date object.

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How to inject Date into bean property using Factory bean in Spring

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%20http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.2.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 dependencies -->

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-core</artifactId>

            <version>${spring.version}</version>

        </dependency>

        <dependency>

            <groupId>org.springframework</groupId>

            <artifactId>spring-context</artifactId>

            <version>${spring.version}</version>

        </dependency>

    </dependencies>

</project>

Employee.java

package com.ram.model;

import java.util.Date;

public class Employee

{

    private String name;

    private Date dateOfBirth;

    public String getName()

    {

        return name;

    }

    public void setName(String name)

    {

        this.name = name;

    }

    public Date getDateOfBirth()

    {

        return dateOfBirth;

    }

    public void setDateOfBirth(Date dateOfBirth)

    {

        this.dateOfBirth = dateOfBirth;

    }

    @Override

    public String toString()

    {

        return "Employee [name=" + name + ", dateOfBirth=" + dateOfBirth + "]";

    }

}

applicationContext.xml

<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-4.3.xsd">

    <bean id="dateFormat" class="java.text.SimpleDateFormat">

        <constructor-arg value="yyyy-MM-dd" />

    </bean>

    <bean id="employee" class="com.ram.model.Employee">

        <property name="name">

            <value>Peter</value>

        </property>

        <property name="dateOfBirth">

            <bean factory-bean="dateFormat" factory-method="parse">

                <constructor-arg value="2010-01-31" />

            </bean>

        </property>

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.model.Employee;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        Employee employee = (Employee) context.getBean("employee");

        System.out.println(

                "Got employee object from the ApplicationContext(Spring Container)");

        System.out.println(employee);

    }

}

Output

Jul 31, 2018 9:55:07 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@5b37e0d2: startup date [Tue Jul 31 09:55:07 IST 2018]; root of context hierarchy

Jul 31, 2018 9:55:07 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

---------------------------------------

Got employee object from the ApplicationContext(Spring Container)

Employee [name=Peter, dateOfBirth=Sun Jan 31 00:00:00 IST 2010]