springboot 手动注册bean实例到spring容器

手动注册bean

此种方式注册的bean在调用时将由spring进行创建，相当于延迟加载bean

 

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;

@Component
public class ApplicationContextUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
        applicationContext=context;
    }


/**
     *  动态注入bean
     * @param requiredType 注入类
     * @param beanName bean名称
     */
    public static Object registerBean(Class<?> requiredType,String beanName){

        //将applicationContext转换为ConfigurableApplicationContext
        ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) applicationContext;

        //获取BeanFactory
        DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) configurableApplicationContext.getAutowireCapableBeanFactory();

        //创建bean信息.
        BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(requiredType);

        //动态注册bean.
        defaultListableBeanFactory.registerBeanDefinition(beanName, beanDefinitionBuilder.getBeanDefinition());

        //获取动态注册的bean.
        return configurableApplicationContext.getBean(requiredType);
    }
｝

 

　　

手动创建bean实例

此种方式允许手动创建单例bean实例并注册，注意必须是单例的，在spring调用时，会将手动创建的bean直接注入到调用方。

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;

@Component
public class ApplicationContextUtil implements ApplicationContextAware {

    private static ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
        applicationContext=context;
    }

    /**
     *  动态注入单例bean实例
     * @param beanName bean名称
     * @param singletonObject 单例bean实例
     * @return 注入实例
     */
    public static Object registerSingletonBean(String beanName,Object singletonObject){

        //将applicationContext转换为ConfigurableApplicationContext
        ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) applicationContext;

        //获取BeanFactory
        DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) configurableApplicationContext.getAutowireCapableBeanFactory();

        //动态注册bean.
        defaultListableBeanFactory.registerSingleton(beanName,singletonObject);

        //获取动态注册的bean.
        return configurableApplicationContext.getBean(beanName);
    }
｝