Spring Prototype scope bean
Spring Prototype scope bean tutorial shows how to use a Prototype scoped bean in a Spring application.
Spring Prototype scope bean
last modified October 18, 2023
Spring Prototype scoped bean tutorial shows how to use a Prototype scoped bean in a Spring application.
Spring is a popular Java application framework for creating enterprise applications.
Spring Prototype bean
Prototype beans are created every time a new request for that bean is made.
Other bean scopes are: singleton, request, session, global session, and application.
Spring Prototype bean example
The application creates two prototype scoped beans and checks if they are identical. The application is a classic Spring 5 console application.
────src ├───main │ ├───java │ │ └───com │ │ └───zetcode │ │ │ Application.java │ │ │ │ │ └───bean │ │ Message.java │ │ │ └───resources │ logback.xml │ my-beans.xml │ └───test └───java
This is the project structure.
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>prototypescopedbean</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.
resources/my-beans.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" xmlns:context=“http://www.springframework.org/schema/context" xsi:schemaLocation=“http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.zetcode"/>
</beans>
With the context:component-scan tag, we instruct Spring to look for beans in the com.zetcode package. It will find our sole Message bean, which is decorated with @Component.
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.
com/zetcode/bean/Message.java
package com.zetcode.bean;
import org.springframework.context.annotation.Scope; import org.springframework.stereotype.Component;
@Component @Scope(“prototype”) public class Message {
private String message;
public String getMessage() {
return message;
}
}
The Message is a Spring bean managed by the Spring container. It has prototype scope.
@Component @Scope(“prototype”) public class Message {
The @Scope(“prototype”) sets the scope of the bean to prototypes; the default is singleton.
com/zetcode/Application.java
package com.zetcode;
import com.zetcode.bean.Message; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.context.support.GenericXmlApplicationContext;
public class Application {
private static final Logger logger = LoggerFactory.getLogger(Application.class);
public static void main(String[] args) {
var ctx = new GenericXmlApplicationContext("my-beans.xml");
var beanA = ctx.getBean(Message.class);
var beanB = ctx.getBean(Message.class);
if (beanA.equals(beanB)) {
logger.info("The beans are identical");
} else {
logger.info("The beans are not identical");
}
ctx.close();
}
}
This is the main application class.
var ctx = new GenericXmlApplicationContext(“my-beans.xml”);
We create the Spring application context from the my-beans.xml file using GenericXmlApplicationContext.
var bean1 = ctx.getBean(Message.class); var bean2 = ctx.getBean(Message.class);
app.run(bean1, bean2);
We get two beans from the application context and pass them to the run method for comparison.
logger.info(a.getMessage());
We read the message from the bean.
if (a.equals(b)) {
logger.info("The beans are the same");
} else {
logger.info("The beans are not the same");
}
We test if the two beans are identical.
$ mvn -q exec:java 21:26:03.089 [com.zetcode.Application.main()] INFO com.zetcode.Application - The beans are not identical
We run the application. Change the spope of the Message bean to singleton and compare the results.
In this article we have worked with a prototype Spring bean.
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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