springboot 手動注冊bean實例到spring容器

手動注冊bean

此種方式注冊的bean在調用時將由spring進行創建，相當於延遲加載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;
    }


/**
     *  動態注入bean
     * @param requiredType 注入類
     * @param beanName bean名稱
     */
    public static Object registerBean(Class<?> requiredType,String beanName){

        //將applicationContext轉換為ConfigurableApplicationContext
        ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) applicationContext;

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

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

        //動態注冊bean.
        defaultListableBeanFactory.registerBeanDefinition(beanName, beanDefinitionBuilder.getBeanDefinition());

        //獲取動態注冊的bean.
        return configurableApplicationContext.getBean(requiredType);
    }
｝

 

　　

手動創建bean實例

此種方式允許手動創建單例bean實例並注冊，注意必須是單例的，在spring調用時，會將手動創建的bean直接注入到調用方。

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;
    }

    /**
     *  動態注入單例bean實例
     * @param beanName bean名稱
     * @param singletonObject 單例bean實例
     * @return 注入實例
     */
    public static Object registerSingletonBean(String beanName,Object singletonObject){

        //將applicationContext轉換為ConfigurableApplicationContext
        ConfigurableApplicationContext configurableApplicationContext = (ConfigurableApplicationContext) applicationContext;

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

        //動態注冊bean.
        defaultListableBeanFactory.registerSingleton(beanName,singletonObject);

        //獲取動態注冊的bean.
        return configurableApplicationContext.getBean(beanName);
    }
｝