SpringBoot启动的时候报错： Error creating bean with name 'XXXX'

完整报错如下：

 Exception encountered during context initialization - cancelling refresh attempt: 
 org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 
 'testHelloController': Unsatisfied dependency expressed through field 'testHelloService'; nested exception is 
 org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 
 'com.jun.service.test.TestHelloService' available: expected at least 1 bean which qualifies as autowire 
 candidate. Dependency annotations: 
 {@org.springframework.beans.factory.annotation.Autowired(required=true)}

原因分析：

因为是初学SpringBoot，只是想先让项目跑起来看看效果如果，费尽半天时间终于把项目结构搭建完整，一启动，就报这样的错，原因人家已经说得很清晰了，也就是在启动的时候找不到TestHelloService这个对象模板进行注入，又看了看service层已经打好注解@Service的，灵机一动，是不是SpringBoot启动的时候没有扫描得到Service层去，后面一看资料，果然如此，在SpringBoot的启动类Application中直接打一个注解@ComponentScan即可解决此问题：
如下：
报错前的代码：

package com.jun.web.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

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

解决报错后的代码：

package com.jun.web.test;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

**@ComponentScan(basePackages = {"com.jun.core.*","com.jun.service.*","com.jun.web.*"})**
@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}