SpringBoot使用ApplicationContext.getBean启动报空指针处理记录

问题：项目启动报空指针

定位：新增filter中init方法使用getbean控制

解决：在新增filter上加注解

@DependsOn({"applicationContextUtils"})

@Component
@DependsOn({"applicationContextUtils"})//此处解决空指针问题
public class XssFilter implements Filter{@Autowiredprivate MultipartResolver multipartResolver=null;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {//注入beanmultipartResolver=(MultipartResolver) ApplicationContextUtils.getApplicationContext().getBean("multipartResolver",MultipartResolver.class);}
}

package com.bonc.ds.web.utils;import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Configuration;import java.util.Locale;//对Spring容器进行各种上下文操作的工具类
@Configuration
public class ApplicationContextUtils implements ApplicationContextAware {private static ApplicationContext context;@Overridepublic void setApplicationContext(ApplicationContext context) throws BeansException {ApplicationContextUtils.context = context;}public static ApplicationContext getApplicationContext(){return context;}//根据Bean名称获取Bean对象public static Object getBean(String beanName){return context.getBean(beanName);}public static Object getMassage(String key){return context.getMessage(key, null, Locale.getDefault());}
}

分析:

ApplicationContextUtils是否在Configuration的Bean初始化之前初始化是未知的。

用到的@DependsOn注解，先把SpringContextUtils注册到Spring容器里面

注解含义就是组件A要依赖于另一个组件B，也就是说被依赖的组件B会比组件A先注册到Spring容器中