Spring boot在普通类中使用service、dao层中的类，只需三步

在一个web项目的jsp中想要使用service中的一个类来获取数据库中的数据，但是用完之后报错说是空指针异常，上网查了之后总结了一下解决办法，只需三步。

1、写一个工具类 SpringUtil

package com.shop.util;

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

public final class SpringUtil implements ApplicationContextAware {
	private static ApplicationContext applicationContext = null;

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
		// TODO Auto-generated method stub
		if (SpringUtil.applicationContext == null) {
			SpringUtil.applicationContext = applicationContext;
			System.out.println(
					"========ApplicationContext配置成功,在普通类可以通过调用ToolSpring.getAppContext()获取applicationContext对象,applicationContext="
							+ applicationContext + "========");
		}
	}
	
	public static ApplicationContext getApplicationContext() {
		return applicationContext;
	}
	
	//通过
	public static Object getBean(String name) {
		return getApplicationContext().getBean(name);
	}
	
	//通过class获取Bean.
    public static  T getBean(Class clazz){
           return getApplicationContext().getBean(clazz);
    }
}

2、在Application启动类中将工具类导入，不然依然无法使用

3、在ApplicationTests测试类中调用

package com.shop.JZShop;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import com.shop.serviceImpl.GoodsServiceImpl;
import com.shop.util.SpringUtil;

@RunWith(SpringRunner.class)
@SpringBootTest
public class JzShopApplicationTests {
	

	@Test
	public void contextLoads() {
		//GoodsServiceImpl为我想要获取的service层中的类
		GoodsServiceImpl goodsServiceImpl = (GoodsServiceImpl)SpringUtil.getBean(GoodsServiceImpl.class);
		System.out.println(goodsServiceImpl.getGoodsByID(27).getGoodsName());
	}
}