问题及背景表述
刚创建了一个小项目
层级大概是这样的
├─.idea
├─Bilibili-api
│ ├─src
│ │ ├─main
│ │ │ ├─java
│ │ │ │ └─com
│ │ │ │ └─xiaosheng
│ │ │ │ └─video
│ │ │ │ └─api
│ │ │ │ ├─config
│ │ │ │ ├─controller
│ │ │ │ ├─request
│ │ │ │ └─response
│ │ │ └─resources
│ │ └─test
│ │ └─java
│ └─target
│ ├─classes
│ │ └─com
│ │ └─xiaosheng
│ │ └─video
│ │ └─api
│ │ └─controller
│ └─generated-sources
│ └─annotations
├─Bilibili-dao
│ ├─src
│ │ ├─main
│ │ │ ├─java
│ │ │ │ └─com
│ │ │ │ └─xiaosheng
│ │ │ │ └─video
│ │ │ │ └─dao
│ │ │ │ ├─mapper
│ │ │ │ └─po
│ │ │ └─resources
│ │ │ └─mapping
│ │ └─test
│ │ └─java
│ └─target
│ ├─classes
│ │ ├─com
│ │ │ └─xiaosheng
│ │ │ └─video
│ │ │ └─dao
│ │ │ └─mapper
│ │ └─mapping
│ └─generated-sources
│ └─annotations
├─Bilibili-facade
│ ├─src
│ │ ├─main
│ │ │ ├─java
│ │ │ │ └─com
│ │ │ │ └─xiaosheng
│ │ │ │ └─video
│ │ │ │ └─facade
│ │ │ │ ├─bo
│ │ │ │ ├─dto
│ │ │ │ └─enums
│ │ │ └─resources
│ │ └─test
│ │ └─java
│ └─target
│ ├─classes
│ ├─maven-archiver
│ └─maven-status
│ └─maven-compiler-plugin
│ ├─compile
│ │ └─default-compile
│ └─testCompile
│ └─default-testCompile
└─Bilibili-services
├─src
│ ├─main
│ │ ├─java
│ │ │ └─com
│ │ │ └─xiaosheng
│ │ │ └─video
│ │ │ └─services
│ │ │ ├─service
│ │ │ └─util
│ │ └─resources
│ └─test
│ └─java
└─target
├─classes
│ └─com
│ └─xiaosheng
│ └─video
│ └─services
│ └─service
└─generated-sources
└─annotations
代码
启动类
@MapperScan("com.xiaosheng.video.dao.mapper")
@SpringBootApplication
public class BilibiliApplication {
public static void main(String[] args) {
ConfigurableApplicationContext run = SpringApplication.run(BilibiliApplication.class, args);
}
}
service
@Service
public class DemoService {
@Resource
private DemoMapper demoMapper;
public Map<String, Map<String, Object>> demo() {
Map<String, Object> stringObjectMap1 = demoMapper.queryallData(1);
Map<String, Object> stringObjectMap2 = demoMapper.queryallData(2);
Map<String, Object> stringObjectMap3 = demoMapper.queryallData(3);
HashMap<String, Map<String, Object>> stringMapHashMap = new HashMap<>();
stringMapHashMap.put("str", stringObjectMap1);
stringMapHashMap.put("str2", stringObjectMap2);
stringMapHashMap.put("str3", stringObjectMap3);
return stringMapHashMap;
}
}
interface
@Mapper
public interface DemoMapper {
Map<String, Object> queryallData(Integer id);
}
mapper.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xiaosheng.video.dao.mapper.DemoMapper">
<select id="queryallData" resultType="java.util.Map">
select * from jdbc_demo where id =#{id}
</select>
</mapper>
运行结果
点击运行的时候就这样了
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.5.1)
2022-09-24 14:40:08.345 INFO 24320 --- [ main] c.x.video.api.BilibiliApplication : Starting BilibiliApplication using Java 1.8.0_112 on LCYITGLB-lipy with PID 24320 (E:\proj\learn\Bilibili\Bilibili-api\target\classes started by CFDL14965 in E:\proj\learn\Bilibili)
2022-09-24 14:40:08.348 INFO 24320 --- [ main] c.x.video.api.BilibiliApplication : The following profiles are active: test
2022-09-24 14:40:09.110 INFO 24320 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8083 (http)
2022-09-24 14:40:09.118 INFO 24320 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2022-09-24 14:40:09.119 INFO 24320 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.46]
2022-09-24 14:40:09.119 INFO 24320 --- [ main] o.a.catalina.core.AprLifecycleListener : Loaded Apache Tomcat Native library [1.2.35] using APR version [1.7.0].
2022-09-24 14:40:09.120 INFO 24320 --- [ main] o.a.catalina.core.AprLifecycleListener : APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
2022-09-24 14:40:09.120 INFO 24320 --- [ main] o.a.catalina.core.AprLifecycleListener : APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true]
2022-09-24 14:40:09.122 INFO 24320 --- [ main] o.a.catalina.core.AprLifecycleListener : OpenSSL successfully initialized [OpenSSL 1.1.1q 5 Jul 2022]
2022-09-24 14:40:09.171 INFO 24320 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2022-09-24 14:40:09.171 INFO 24320 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 785 ms
2022-09-24 14:40:09.217 WARN 24320 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'demoController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.xiaosheng.video.services.service.DemoService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@javax.annotation.Resource(shareable=true, lookup=, name=, description=, authenticationType=CONTAINER, type=class java.lang.Object, mappedName=)}
2022-09-24 14:40:09.219 INFO 24320 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2022-09-24 14:40:09.233 INFO 24320 --- [ main] ConditionEvaluationReportLoggingListener :
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-09-24 14:40:09.249 ERROR 24320 --- [ main] o.s.b.d.LoggingFailureAnalysisReporter :
***************************
APPLICATION FAILED TO START
***************************
Description:
A component required a bean of type 'com.xiaosheng.video.services.service.DemoService' that could not be found.
Action:
Consider defining a bean of type 'com.xiaosheng.video.services.service.DemoService' in your configuration.
Process finished with exit code 1
求解
在网上找了很久，无非几个解法
mapper interface没写@mapper注解-
启动类没写
@MapperScan("com.xiaosheng.video.dao.mapper") -
service层没写@service,或者controller没有把service注入 -
目录层级不对
四个解决方法和我一个不搭边
解决方法
解决方法
在启动类上方添加如下注解
@ComponentScan(basePackages = {"com.xiaosheng"})
@ComponentScan(basePackages = {"com.xiaosheng"})
@MapperScan("com.xiaosheng.video.dao.mapper")
@SpringBootApplication
public class BilibiliApplication {
public static void main(String[] args) {
ConfigurableApplicationContext run = SpringApplication.run(BilibiliApplication.class, args);
}
}
原理
@ComponentScan主要就是定义扫描的路径从中找出标识了需要装配的类自动装配到spring的bean容器中
@Controller，@Service，@Repository注解，他们中有一个共同的注解@Component，没错@ComponentScan注解默认就会装配标识了@Controller，@Service，@Repository，@Component注解的类到spring容器中
通过includeFilters加入扫描路径下没有以上注解的类加入spring容器
通过excludeFilters过滤出不用加入spring容器的类
