Spring BeanDefinitionBuilder tutorial

last modified October 18, 2023

Spring BeanDefinitionBuilder tutorial shows how to programatically create new Spring beans using BeanDefinitionBuilder.

Spring is a popular Java application framework for creating enterprise applications.

BeanDefinitionBuilder

BeanDefinitionBuilder is used to create new Spring beans programatically. It utilizes the builder pattern.

Spring BeanDefinitionBuilder example

The application creates create a simple string bean.

pom.xml

<?xml version=“1.0” encoding=“UTF-8”?> <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>com.zetcode</groupId>
<artifactId>beanbuilderex</artifactId>
<version>1.0-SNAPSHOT</version>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>17</maven.compiler.source>
    <maven.compiler.target>17</maven.compiler.target>
    <spring-version>5.3.23</spring-version>

</properties>

<dependencies>

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.4.0</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${spring-version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>${spring-version}</version>
    </dependency>
    
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>3.1.0</version>
            <configuration>
                <mainClass>com.zetcode.Application</mainClass>
            </configuration>
        </plugin>
    </plugins>
</build>

</project>

In the pom.xml file, we have basic Spring dependencies spring-core and spring-context and logging logback-classic dependency.

The exec-maven-plugin is used for executing Spring application from the Maven on the command line.

src/main/resources/logback.xml

<?xml version=“1.0” encoding=“UTF-8”?> <configuration> <logger name=“org.springframework” level=“ERROR”/> <logger name=“com.zetcode” level=“INFO”/>

<appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
        <Pattern>%d{HH:mm:ss.SSS} [%thread] %blue(%-5level) %magenta(%logger{36}) - %msg %n
        </Pattern>
    </encoder>
</appender>

<root>
    <level value="INFO" />
    <appender-ref ref="consoleAppender" />
</root>

</configuration>

The logback.xml is a configuration file for the Logback logging library.

src/main/java/com/zetcode/Application.java

package com.zetcode;

import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.support.BeanDefinitionBuilder; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.context.annotation.AnnotationConfigApplicationContext; import org.springframework.context.annotation.ComponentScan;

@ComponentScan(basePackages = “com.zetcode”) public class Application {

private static final Logger logger = LoggerFactory.getLogger(Application.class);

public static void main(String[] args) {

    var ctx = new AnnotationConfigApplicationContext(Application.class);

    var beanFactory = (BeanDefinitionRegistry) ctx.getBeanFactory();

    beanFactory.registerBeanDefinition("myBean",
            BeanDefinitionBuilder.genericBeanDefinition(String.class)
                    .addConstructorArgValue("This is my bean")
                    .setScope("prototype")
                    .getBeanDefinition()
    );

    logger.info("{}", ctx.getBean("myBean"));

    ctx.close();
}

}

The example creates a simple bean of type String using BeanDefinitionBuilder.

var beanFactory = (BeanDefinitionRegistry) ctx.getBeanFactory();

A bean factory is retrieved from the application context with getBeanFactory.

beanFactory.registerBeanDefinition(“myBean”, BeanDefinitionBuilder.genericBeanDefinition(String.class) .addConstructorArgValue(“This is my bean”) .setScope(“prototype”) .getBeanDefinition() );

We register a new bean with registerBeanDefinition.

logger.info(”{}”, ctx.getBean(“myBean”));

We get the bean from the application context with getBean
and log it.

$ mvn -q exec:java 20:51:05.970 [com.zetcode.Application.main()] INFO com.zetcode.Application - This is my bean

We run the application.

In this article we have used the BeanDefinitionBuilder to register a new Spring bean programatically.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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