SSM项目中,普通类中调用Service

柔光的暖阳◎ 2022-06-08 05:00 275阅读 0赞

一开始在普通类中调用Service,报的空指针异常.

找的的解决方法如下:

1.写一个SpringInit辅助类,代码如下:

import javax.servlet.ServletContextEvent;  
import javax.servlet.ServletContextListener;  
  
  
import org.springframework.context.ApplicationContext;  
import org.springframework.web.context.WebApplicationContext;  
import org.springframework.web.context.support.WebApplicationContextUtils;  
  
  
public class SpingInit implements ServletContextListener\{  
  
private static WebApplicationContext springContext;  
  
public SpingInit()\{  
super();  
\}  
  
@Override  
public void contextDestroyed(ServletContextEvent arg0) \{  
// TODO Auto-generated method stub  
\}  
  
  
@Override  
public void contextInitialized(ServletContextEvent event) \{  
springContext = WebApplicationContextUtils.getWebApplicationContext(event.getServletContext());   
\}  
public static ApplicationContext getApplicationContext() \{       
        return springContext;      
  
  
\}  
  
  
\}

2.把该类所在的包要被spring扫描

<context:component-scan base-package="com.test.utils" />

3.在web.xml中加入该类的监听事件

<listener>  
    <listener-class>com.test.utils.SpingInit</listener-class>  
  </listener>

4.在普通类中调用:

NotifyManagementInfoService notifyManagementInfoService =   
(NotifyManagementInfoService) SpingInit.getApplicationContext().getBean("notifyManagementInfoServiceImpl");

若不知道bean的被命名成什么,可在xml中加入

会报expected single matching bean but found 2: testService,customerServiceImpl异常,可查看bean被命名成什么....

我小白一个,在这里的时候还吃亏了...

好了,终于可以在普通类中进行操作了

notifyManagementInfoService.add(notifyManagementInfo);

参考博客:http://www.cnblogs.com/chongerlishan/p/5942033.html

\-----------------------------------------------------------2018/8/6更新-----------------------------------------------------------------------------------

偶然遇到一位神人写的SpringUtils工具类,发现比我的之前找的方法好使多了,特此更新.

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;
     
     
    public final class SpringUtils implements BeanFactoryPostProcessor {
     
     
    	private static ConfigurableListableBeanFactory beanFactory; // Spring应用上下文环境
     
     
    	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
    		SpringUtils.beanFactory = beanFactory;
    	}
     
     
    	/**
    	 * 获取对象
    	 * 
    	 * @param name
    	 * @return Object 一个以所给名字注册的bean的实例
    	 * @throws org.springframework.beans.BeansException
    	 * 
    	 */
    	@SuppressWarnings("unchecked")
    	public static <T> T getBean(String name) throws BeansException {
    		return (T) beanFactory.getBean(name);
    	}
     
     
    	/**
    	 * 获取类型为requiredType的对象
    	 * 
    	 * @param clz
    	 * @return
    	 * @throws org.springframework.beans.BeansException
    	 * 
    	 */
    	public static <T> T getBean(Class<T> clz) throws BeansException {
    		@SuppressWarnings("unchecked")
    		T result = (T) beanFactory.getBean(clz);
    		return result;
    	}
     
     
    	/**
    	 * 如果BeanFactory包含一个与所给名称匹配的bean定义，则返回true
    	 * 
    	 * @param name
    	 * @return boolean
    	 */
    	public static boolean containsBean(String name) {
    		return beanFactory.containsBean(name);
    	}
     
     
    	/**
    	 * 判断以给定名字注册的bean定义是一个singleton还是一个prototype。
    	 * 如果与给定名字相应的bean定义没有被找到，将会抛出一个异常（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 注册对象的类型
    	 * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
    	 * 
    	 */
    	public static Class<?> getType(String name) throws NoSuchBeanDefinitionException {
    		return beanFactory.getType(name);
    	}
     
     
    	/**
    	 * 如果给定的bean名字在bean定义中有别名，则返回这些别名
    	 * 
    	 * @param name
    	 * @return
    	 * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
    	 * 
    	 */
    	public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
    		return beanFactory.getAliases(name);
    	}
     
     
    }

添加到bean中：

@Bean
    	public SpringUtils springUtils() {
    		return new SpringUtils();
    	}

监听也不用了,bean的名字也不用知道了...直接如此调用:

A a=SpringUtils.getBean(A.class);

相见恨晚,告辞!

\-----------------------------------------------------------2019/11/6更新-----------------------------------------------------------------------------------

在多线程时使用@Autowired总是获取不到bean，原因是：new thread不在spring容器中，也就无法获得spring中的bean对象。

解决方法：手动获取

package com.test.configs;
     
    import org.springframework.beans.BeansException;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ApplicationContextAware;
    import org.springframework.stereotype.Component;
     
    @Component
    public class BeanContext implements ApplicationContextAware {
     
    	private static ApplicationContext applicationContext;
    	
    	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    		BeanContext.applicationContext = applicationContext;
    	}
    	
    	public static ApplicationContext getApplicationContext(){
    		return applicationContext;
    	}
    	
    	@SuppressWarnings("unchecked")
    	public static <T> T getBean(String name) throws BeansException {
    		return (T)applicationContext.getBean(name);
    	}
    	
    	public static <T> T getBean(Class<T> clz) throws BeansException {
    	    return (T)applicationContext.getBean(clz);
    	}
    }

创建thread

package com.test.handler;
     
    import com.test.configs.BeanContext;
    import com.test.service.TestService;
    import com.test.model.User;
     
    /**
     * created by huguoju on 2017/11/13.
     */
    public class TestHandler implements Runnable {
     
        private User user;
        private TestService testService;
        @Override
        public void run() {
            this.testService= BeanContext.getApplicationContext().getBean(TestService.class);
            User user=testService.queryUserById(11);
        }
     
        public User getUser() {
            return user;
        }
     
        public void setUser(User user) {
            this.user = user;
        }
    }

原文地址：[https://blog.csdn.net/u011493599/article/details/78522315][https_blog.csdn.net_u011493599_article_details_78522315]

[https_blog.csdn.net_u011493599_article_details_78522315]: https://blog.csdn.net/u011493599/article/details/78522315