Spring中如何获取JavaBean呢?

书欣 Spring 2022-09-16 22:04:21 4482 1
下文笔者讲述Spring中获取Bean的方法分享,如下所示
我们都知道,Spring中可使用@Resource/@Autowired
即可获取Spring对象,但是有些特殊的场景,我们只能通过另外的方式获取bean
下文笔者将一一道来,如下所示
例:
SpringBoot获取Bean的方法

方式1:SpringBoot 获取ApplicationContext

    @Autowired  
    ApplicationContext context; 
 

方式2:继承ApplicationContextAware 来获取Bean

创建一个类继承ApplicationContextAware
package com.java265;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
public class ApplicationContextUtil implements ApplicationContextAware {
    private static ApplicationContext applicationContext;
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException{
        this.applicationContext = applicationContext;
    }
    public static ApplicationContext getContext() {
        return applicationContext;
    }
    public static <T> T getBean(String name) {
        if (applicationContext == null) {
            return null;
        }
        return (T) applicationContext.getBean(name);
    }
}
将ApplicationContextAware 配置进application-context.xml
<bean id="applicationContextUtil" class="com.java265.ApplicationContextUtil"/>

方式3:获取bean的使用场景

TestBean testBean = ApplicationContextUtil.getBean("bean名称");
 

方式4:使用ContextLoader 获取bean

ApplicationContext app = ContextLoader.getCurrentWebApplicationContext();
TestBean testBean = app.getBean("testBean", TestBean.class);

方式5:继承 BeanFactoryAware 获取bean

创建一个类继承BeanFactoryAware
package com.java265;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
 
public class SpringBeanFactory implements BeanFactoryAware {
    private static BeanFactory beanFactory;
    @Override
    public void setBeanFactory(BeanFactory factory) throws BeansException {
        this.beanFactory = factory;
    }
 
    /**
     * 根据beanName名字取得bean
     * @param name
     * @param <T>
     * @return
     */
    public static <T> T getBean(String name) {
        if (beanFactory == null) {
            return null;
        }
        return (T) beanFactory.getBean(name);
    }
}

SpringBeanFactory 配置进application-context.xml

<bean id="springBeanFactory" class="com.java265.SpringBeanFactory"/>
在需要的地方获取bean

TestBean testBean = SpringBeanFactory.getBean("bean名称");
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