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Spring - Injecting Prototype Bean Using Java 8 Functions

[Last Updated: Jul 24, 2022]

This example shows how to use Java 8 functions to solve shorter-lived bean injection problem.

We are going to inject java.util.function.Function into a singleton bean. Whenever Function#apply() method is called, it will return a new instance of a prototype bean.

Example

Prototype bean

package com.logicbig.example;

public class MyPrototypeBean {
  private String message;

  public MyPrototypeBean(String message) {
      this.message = message;
  }

  public String getMessage() {
      return message;
  }
}

Singleton bean

package com.logicbig.example;

import org.springframework.beans.factory.annotation.Autowired;
import java.util.function.Function;

public class MySingletonBean {

  @Autowired
  private Function<String, MyPrototypeBean> myPrototypeBeanFunction;

  public void showMessage() {
      MyPrototypeBean bean = myPrototypeBeanFunction.apply("Hi there!");
      System.out.printf("message: %s - instance: %s%n", bean.getMessage(), System.identityHashCode(bean));
  }
}

Defining beans and running main method

package com.logicbig.example;

import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Scope;
import java.util.function.Function;

@Configuration
public class AppConfig {

  @Bean
  @Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
  public MyPrototypeBean prototypeBean(String name) {
      return new MyPrototypeBean(name);
  }

  @Bean
  public Function<String, MyPrototypeBean> prototypeBeanFunction() {
      return name -> prototypeBean(name);
  }

  @Bean
  public MySingletonBean singletonBean() {
      return new MySingletonBean();
  }

  public static void main(String[] args) {
      AnnotationConfigApplicationContext context =
              new AnnotationConfigApplicationContext(AppConfig.class);
      MySingletonBean bean = context.getBean(MySingletonBean.class);
      bean.showMessage();
      // one more time
      bean = context.getBean(MySingletonBean.class);
      bean.showMessage();
  }
}

Output

message: Hi there! - instance: 1071410267
message: Hi there! - instance: 1563125357

Example Project

Dependencies and Technologies Used:

  • spring-context 5.3.22 (Spring Context)
     Version Compatibility: 4.1.3.RELEASE - 5.3.22 Version List
    ×

    Version compatibilities of spring-context with this example:

    • 4.1.3.RELEASE
    • 4.1.4.RELEASE
    • 4.1.5.RELEASE
    • 4.1.6.RELEASE
    • 4.1.7.RELEASE
    • 4.1.8.RELEASE
    • 4.1.9.RELEASE
    • 4.2.0.RELEASE
    • 4.2.1.RELEASE
    • 4.2.2.RELEASE
    • 4.2.3.RELEASE
    • 4.2.4.RELEASE
    • 4.2.5.RELEASE
    • 4.2.6.RELEASE
    • 4.2.7.RELEASE
    • 4.2.8.RELEASE
    • 4.2.9.RELEASE
    • 4.3.0.RELEASE
    • 4.3.1.RELEASE
    • 4.3.2.RELEASE
    • 4.3.3.RELEASE
    • 4.3.4.RELEASE
    • 4.3.5.RELEASE
    • 4.3.6.RELEASE
    • 4.3.7.RELEASE
    • 4.3.8.RELEASE
    • 4.3.9.RELEASE
    • 4.3.10.RELEASE
    • 4.3.11.RELEASE
    • 4.3.12.RELEASE
    • 4.3.13.RELEASE
    • 4.3.14.RELEASE
    • 4.3.15.RELEASE
    • 4.3.16.RELEASE
    • 4.3.17.RELEASE
    • 4.3.18.RELEASE
    • 4.3.19.RELEASE
    • 4.3.20.RELEASE
    • 4.3.21.RELEASE
    • 4.3.22.RELEASE
    • 4.3.23.RELEASE
    • 4.3.24.RELEASE
    • 4.3.25.RELEASE
    • 4.3.26.RELEASE
    • 4.3.27.RELEASE
    • 4.3.28.RELEASE
    • 4.3.29.RELEASE
    • 4.3.30.RELEASE
    • 5.0.0.RELEASE
    • 5.0.1.RELEASE
    • 5.0.2.RELEASE
    • 5.0.3.RELEASE
    • 5.0.4.RELEASE
    • 5.0.5.RELEASE
    • 5.0.6.RELEASE
    • 5.0.7.RELEASE
    • 5.0.8.RELEASE
    • 5.0.9.RELEASE
    • 5.0.10.RELEASE
    • 5.0.11.RELEASE
    • 5.0.12.RELEASE
    • 5.0.13.RELEASE
    • 5.0.14.RELEASE
    • 5.0.15.RELEASE
    • 5.0.16.RELEASE
    • 5.0.17.RELEASE
    • 5.0.18.RELEASE
    • 5.0.19.RELEASE
    • 5.0.20.RELEASE
    • 5.1.0.RELEASE
    • 5.1.1.RELEASE
    • 5.1.2.RELEASE
    • 5.1.3.RELEASE
    • 5.1.4.RELEASE
    • 5.1.5.RELEASE
    • 5.1.6.RELEASE
    • 5.1.7.RELEASE
    • 5.1.8.RELEASE
    • 5.1.9.RELEASE
    • 5.1.10.RELEASE
    • 5.1.11.RELEASE
    • 5.1.12.RELEASE
    • 5.1.13.RELEASE
    • 5.1.14.RELEASE
    • 5.1.15.RELEASE
    • 5.1.16.RELEASE
    • 5.1.17.RELEASE
    • 5.1.18.RELEASE
    • 5.1.19.RELEASE
    • 5.1.20.RELEASE
    • 5.2.0.RELEASE
    • 5.2.1.RELEASE
    • 5.2.2.RELEASE
    • 5.2.3.RELEASE
    • 5.2.4.RELEASE
    • 5.2.5.RELEASE
    • 5.2.6.RELEASE
    • 5.2.7.RELEASE
    • 5.2.8.RELEASE
    • 5.2.9.RELEASE
    • 5.2.10.RELEASE
    • 5.2.11.RELEASE
    • 5.2.12.RELEASE
    • 5.2.13.RELEASE
    • 5.2.14.RELEASE
    • 5.2.15.RELEASE
    • 5.2.16.RELEASE
    • 5.2.17.RELEASE
    • 5.2.18.RELEASE
    • 5.2.19.RELEASE
    • 5.2.20.RELEASE
    • 5.2.21.RELEASE
    • 5.2.22.RELEASE
    • 5.3.0
    • 5.3.1
    • 5.3.2
    • 5.3.3
    • 5.3.4
    • 5.3.5
    • 5.3.6
    • 5.3.7
    • 5.3.8
    • 5.3.9
    • 5.3.10
    • 5.3.11
    • 5.3.12
    • 5.3.13
    • 5.3.14
    • 5.3.15
    • 5.3.16
    • 5.3.17
    • 5.3.18
    • 5.3.19
    • 5.3.20
    • 5.3.21
    • 5.3.22

    Versions in green have been tested.

  • JDK 8
  • Maven 3.8.1

Using Java 8 Functions to solve Incompatible Bean Scopes problem Select All Download
  • spring-injecting-prototype-bean-using-java-8-functions
    • src
      • main
        • java
          • com
            • logicbig
              • example
                • MySingletonBean.java

    See Also