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> T getBean(Class<T> 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());
}
}