报错信息如下

.   ____          _            __ _ _
/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/  ___)| |_)| | | | | || (_| |  ) ) ) )
'  |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot ::        (v2.0.1.RELEASE)

2019-05-17 11:59:15.026  INFO 7792 --- [           main] com.bdqn.Start                           : Starting Start on PC-20180826RQMV with PID 7792 (E:\IDEA\springboot1\target\classes started by Administrator in E:\IDEA\springboot1)
2019-05-17 11:59:15.031  INFO 7792 --- [           main] com.bdqn.Start                           : The following profiles are active: dev
2019-05-17 11:59:15.115  INFO 7792 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4f6ee6e4: startup date [Fri May 17 11:59:15 CST 2019]; root of context hierarchy
2019-05-17 11:59:16.638  INFO 7792 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8888 (http)
2019-05-17 11:59:16.663  INFO 7792 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-05-17 11:59:16.663  INFO 7792 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
2019-05-17 11:59:16.667  INFO 7792 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : Loaded APR based Apache Tomcat Native library [1.2.18] using APR version [1.6.5].
2019-05-17 11:59:16.668  INFO 7792 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].
2019-05-17 11:59:16.668  INFO 7792 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true]
2019-05-17 11:59:16.671  INFO 7792 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1  11 Sep 2018]
2019-05-17 11:59:16.864  INFO 7792 --- [ost-startStop-1] org.apache.jasper.servlet.TldScanner     : At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time.
2019-05-17 11:59:16.867  INFO 7792 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-05-17 11:59:16.868  INFO 7792 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1759 ms
2019-05-17 11:59:16.998  INFO 7792 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
2019-05-17 11:59:17.002  INFO 7792 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2019-05-17 11:59:17.002  INFO 7792 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2019-05-17 11:59:17.002  INFO 7792 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2019-05-17 11:59:17.002  INFO 7792 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2019-05-17 11:59:17.041  WARN 7792 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'testController': Unsatisfied dependency expressed through field 'testService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'testServices': Unsatisfied dependency expressed through field 'testDao'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.bdqn.dao.TestDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2019-05-17 11:59:17.044  INFO 7792 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2019-05-17 11:59:17.052  WARN 7792 --- [ost-startStop-1] o.a.c.loader.WebappClassLoaderBase       : The web application [ROOT] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.lang.Object.wait(Native Method)
java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:144)
com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:43)
2019-05-17 11:59:17.061  INFO 7792 --- [           main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-05-17 11:59:17.194 ERROR 7792 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   :

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

Description:

Field testDao in com.bdqn.service.TestServices required a bean of type 'com.bdqn.dao.TestDao' that could not be found.

Action:

Consider defining a bean of type 'com.bdqn.dao.TestDao' in your configuration.

Process finished with exit code 1

这种报错情况有两种：

第一种：启动类注解上有@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)

            解决办法  去掉(exclude = DataSourceAutoConfiguration.class)

第二种：dao的接口使用注解 @Repository

            解决办法：将 @Repository修改为@Mapper

情况一：

启动类：

package com.bdqn;

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

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

Dao层

package com.bdqn.dao;

import com.bdqn.pojo.Test;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.List;

@Mapper
public interface TestDao {

@Select("select * from user")
List<Test> getAll();
}

解决办法：将启动类后面的(exclude = DataSourceAutoConfiguration.class)去掉

package com.bdqn;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
@SpringBootApplication
public class Start {
public static void main(String[] args) {
SpringApplication.run(Start.class,args);
}
}

情况二：

    启动类

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

    dao层

package com.bdqn.dao;

import com.bdqn.pojo.Test;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface TestDao {

@Select("select * from user")
List<Test> getAll();
}

解决办法：将@Repository修改为@Mapper