Spring源码学习--从Springboot的ApplicationContext获取Bean

某些类A无法注入的情况下,需要用到其他被Spring注入的对象B,此时在A类如果想使用B,可以采取下面的方式

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;

/**
 * Description:获取bean工具
 * 
 * @author DemoTransfer
 * @date 2018年5月19日 下午1:42:56
 */
public class SpringBeanUtil {

    private static ApplicationContext applicationContext;
    static final private Object lock = new Object();

    /**
     * 设置上下文
     * 
     * @param applicationContext
     * @throws BeansException
     */
    public static void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        synchronized (lock) {
            if (SpringBeanUtil.applicationContext == null) {
                SpringBeanUtil.applicationContext = applicationContext;
            }
        }
    }

    /**
     * 获取applicationContext
     * 
     * @return
     */
    public static ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * 通过name获取 Bean
     * 
     * @param name
     * @return
     */
    public static Object getBean(String name) {
        return getApplicationContext().getBean(name);
    }

    /**
     * 通过class获取Bean
     * 
     * @param clazz
     * @return
     */
    public static  T getBean(Class clazz) {
        return getApplicationContext().getBean(clazz);
    }

    /**
     * 通过name,以及Clazz返回指定的Bean
     * 
     * @param name
     * @param clazz
     * @return
     */
    public static  T getBean(String name, Class clazz) {
        return getApplicationContext().getBean(name, clazz);
    }
}

设置ApplicationContext地方

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
public class WebApplication {

    private static ApplicationContext applicationContext;

    public static void main(String[] args) {
        applicationContext = SpringApplication.run(WebApplication.class, args);
        SpringBeanUtil.setApplicationContext(applicationContext);
    }

}

使用场景

UnInstallServiceImpl unInstallServiceImpl = (UnInstallServiceImpl) SpringBeanUtil.getBean("unInstallService");