Spring 引导 - 在 IOC 容器中将 Bean 创建为单例

Question

Bean 创建应该是 spring 容器中的单例，对吗？我正在将 Spring 配置文件迁移到 Spring Boot with Annotations。我有下面的代码，但它似乎每次在另一个 bean 创建中使用它时都会调用 "mySingletonBean()" 。据我了解，@Bean 注释默认情况下应该是 Singleton。我是否正确地创建了我的 Bean？

@Bean
public SomeBean mySingletonBean() {
  SomeBean mybean = new SomeBean();
  mybean.setName = "Name";
  return mybean;
}

@Bean 
public Bean1 bean1() {
  Bean1 bean1 = new Bean1();
  bean1.setBean(mySingletonBean());
  return bean1;
}

@Bean 
public Bean2 bean2() {
  Bean2 bean2 = new Bean2();
  bean2.setBean(mySingletonBean());
  return bean2;
}

Answer 1

Spring Boot 是智能框架和方法 mySingletonBean() 只会启动一次，不用担心。你可以启动调试模式并查看。

Answer 2

Spring 正在代理您的应用程序上下文 class，并负责所有与上下文相关的事情，例如 bean 的实例化、缓存等。

运行这个小测试，随意调试看看class配置class变成了什么：

package Whosebug;

import java.util.Arrays;
import java.util.Date;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.junit.Assert.assertTrue;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = Test.MyContext.class)
public class Test {

    @Autowired
    private ApplicationContext applicationContext;
    @Autowired
    @Qualifier("myStringBean")
    private String myStringBean;
    @Autowired
    private SomeBean someBean;

    @Configuration
    static class MyContext {

        @Bean
        public String myStringBean() {
            return String.valueOf(new Date().getTime());
        }

        @Bean
        public SomeBean mySomeBean() {
            return new SomeBean(myStringBean());
        }

    }

    @org.junit.Test
    public void test() {
        assertTrue(myStringBean == applicationContext.getBean("myStringBean"));
        assertTrue(myStringBean == someBean.getValue());
        System.out.println(Arrays.asList(applicationContext.getBean("myStringBean"), myStringBean, someBean.getValue()));
    }

    static class SomeBean {

        private String value;

        public SomeBean(String value) {
            this.value = value;
        }

        public String getValue() {
            return value;
        }
    }

}

Spring 引导 - 在 IOC 容器中将 Bean 创建为单例

Spring Boot - creating Bean as Singleton in IOC container

java

spring

spring-boot

ioc-container