springboot启动常见错误

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'checkItemServiceImpl': Unsatisfied dependency expressed through field 'baseMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.ifjanuary.mapper.CheckItemMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

解决办法：在启动类上添加上包扫描

@MapperScan("com.xxx.mapper")

=============================================================================================================================================================

***************************
APPLICATION FAILED TO START
***************************

Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

Reason: Failed to determine a suitable driver class


Action:

Consider the following:
    If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
    If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).

这是消费端，应该是不需要提供数据库连接的

首先排查下消费端的pom文件中的依赖，把有关数据库连接的依赖删掉，一定要记得刷新maven仓库，我就是搞了很久一直是这个错，但是一刷新maven仓库就好了；

如果是分为消费端和提供端的，可以把消费端的controller类放到提供端试试，看看在提供端能不能跑起来；

之后再排查每个类所在的包和层级关系，我错把service接口放在了pojo包下，最后是解决了，所以在搬砖时一定要认真

=============================================================================================================================================================

java.lang.IllegalStateException: Serialized class com.ifjanuary.pojo.CheckItem must implement java.io.Serializable

在实体类中实现接口

Serializable

====================================================================================================================================================================================

javax.servlet.ServletException: Circular view path [selectSetmealRate]: would dispatch back to the current handler URL [/xxxxxx] again. Check your ViewResolver setup! (Hint: This may be the result of an unspecified view, due to default view name generation.)

因为返回前端需要json格式的数据，可以直接在controller层加上注解：

//@Controller
@RestController  不用@Controller
也可以
在方法上加注解@responsebody  选其一就好