springboot獲取getBean方法以及ApplicationContext空指針問題解決

     場景：在springboot多模塊中使用getBean獲取bean導致空指針異常。

     假如有個工程有common模塊和admin(啟動類模塊)模塊，獲取getBean的類在admin中，則不會報空指針，如果在common模塊中，在admin模塊中調用，則會報空指針異常，解決方法，使用@Import導入getBean方法所在的類。

@SpringBootApplication
@Import(SpringContextHolder.class)
public class AdminApplication {

    public static void main(String[] args) {
        SpringApplication.run(OathServiceApplication.class, args);
    }

}

import org.springframework.aop.framework.AopContext;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.stereotype.Component;

import java.lang.annotation.Annotation;
import java.util.Map;

/**
 * spring工具類 方便在非spring管理環境中獲取bean
 **/
@Component
public final class SpringContextHolder implements BeanFactoryPostProcessor
{
    /** Spring應用上下文環境 */
    private static ConfigurableListableBeanFactory beanFactory;

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException
    {
        SpringContextHolder.beanFactory = beanFactory;
    }

    /**
     * 獲取對象
     *
     * @param name
     * @return Object 一個以所給名字注冊的bean的實例
     * @throws org.springframework.beans.BeansException
     *
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) throws BeansException
    {
        return (T) beanFactory.getBean(name);
    }

    /**
     * 獲取類型為requiredType的對象
     *
     * @param clz
     * @return
     * @throws org.springframework.beans.BeansException
     *
     */
    public static <T> T getBean(Class<T> clz) throws BeansException
    {
        T result = (T) beanFactory.getBean(clz);
        return result;
    }

    /**
     * 如果BeanFactory包含一個與所給名稱匹配的bean定義，則返回true
     *
     * @param name
     * @return boolean
     */
    public static boolean containsBean(String name)
    {
        return beanFactory.containsBean(name);
    }

    /**
     * 判斷以給定名字注冊的bean定義是一個singleton還是一個prototype。 如果與給定名字相應的bean定義沒有被找到，將會拋出一個異常（NoSuchBeanDefinitionException）
     *
     * @param name
     * @return boolean
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException
    {
        return beanFactory.isSingleton(name);
    }

    /**
     * @param name
     * @return Class 注冊對象的類型
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static Class<?> getType(String name) throws NoSuchBeanDefinitionException
    {
        return beanFactory.getType(name);
    }

    /**
     * 如果給定的bean名字在bean定義中有別名，則返回這些別名
     *
     * @param name
     * @return
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static String[] getAliases(String name) throws NoSuchBeanDefinitionException
    {
        return beanFactory.getAliases(name);
    }


    public static Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType){
        return beanFactory.getBeansWithAnnotation(annotationType);
    }

    /**
     * 獲取aop代理對象
     *
     * @param invoker
     * @return
     */
    @SuppressWarnings("unchecked")
    public static <T> T getAopProxy(T invoker)
    {
        return (T) AopContext.currentProxy();
    }
}