记一次 新建 springboot 项目 ，启动失败的经历

我用idea （spring initializr）新建了一个springboot项目，项目中用到了（勾选了） web 、mybatis  mysql ，实际上项目中还没有配置连接数据库 ，在启动时报以下错误：

"C:\Program Files\Java\jdk1.8.0_101\bin\java" -Didea.launcher.port=7536 "-Didea.launcher.bin.path=D:\softinstall\IntelliJ IDEA 15.0.1\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.8.0_101\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_101\jre\lib\rt.jar;D:\java_project\06\target\classes;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter-web\2.1.5.RELEASE\spring-boot-starter-web-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter\2.1.5.RELEASE\spring-boot-starter-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot\2.1.5.RELEASE\spring-boot-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-autoconfigure\2.1.5.RELEASE\spring-boot-autoconfigure-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter-logging\2.1.5.RELEASE\spring-boot-starter-logging-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\ch\qos\logback\logback-classic\1.2.3\logback-classic-1.2.3.jar;D:\Software\apache-maven-3.3.9\repo\ch\qos\logback\logback-core\1.2.3\logback-core-1.2.3.jar;D:\Software\apache-maven-3.3.9\repo\org\apache\logging\log4j\log4j-to-slf4j\2.11.2\log4j-to-slf4j-2.11.2.jar;D:\Software\apache-maven-3.3.9\repo\org\apache\logging\log4j\log4j-api\2.11.2\log4j-api-2.11.2.jar;D:\Software\apache-maven-3.3.9\repo\org\slf4j\jul-to-slf4j\1.7.26\jul-to-slf4j-1.7.26.jar;D:\Software\apache-maven-3.3.9\repo\javax\annotation\javax.annotation-api\1.3.2\javax.annotation-api-1.3.2.jar;D:\Software\apache-maven-3.3.9\repo\org\yaml\snakeyaml\1.23\snakeyaml-1.23.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter-json\2.1.5.RELEASE\spring-boot-starter-json-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\core\jackson-databind\2.9.8\jackson-databind-2.9.8.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\core\jackson-annotations\2.9.0\jackson-annotations-2.9.0.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\core\jackson-core\2.9.8\jackson-core-2.9.8.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.9.8\jackson-datatype-jdk8-2.9.8.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.9.8\jackson-datatype-jsr310-2.9.8.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\jackson\module\jackson-module-parameter-names\2.9.8\jackson-module-parameter-names-2.9.8.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter-tomcat\2.1.5.RELEASE\spring-boot-starter-tomcat-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\apache\tomcat\embed\tomcat-embed-core\9.0.19\tomcat-embed-core-9.0.19.jar;D:\Software\apache-maven-3.3.9\repo\org\apache\tomcat\embed\tomcat-embed-el\9.0.19\tomcat-embed-el-9.0.19.jar;D:\Software\apache-maven-3.3.9\repo\org\apache\tomcat\embed\tomcat-embed-websocket\9.0.19\tomcat-embed-websocket-9.0.19.jar;D:\Software\apache-maven-3.3.9\repo\org\hibernate\validator\hibernate-validator\6.0.16.Final\hibernate-validator-6.0.16.Final.jar;D:\Software\apache-maven-3.3.9\repo\javax\validation\validation-api\2.0.1.Final\validation-api-2.0.1.Final.jar;D:\Software\apache-maven-3.3.9\repo\org\jboss\logging\jboss-logging\3.3.2.Final\jboss-logging-3.3.2.Final.jar;D:\Software\apache-maven-3.3.9\repo\com\fasterxml\classmate\1.4.0\classmate-1.4.0.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-web\5.1.7.RELEASE\spring-web-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-beans\5.1.7.RELEASE\spring-beans-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-webmvc\5.1.7.RELEASE\spring-webmvc-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-aop\5.1.7.RELEASE\spring-aop-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-context\5.1.7.RELEASE\spring-context-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-expression\5.1.7.RELEASE\spring-expression-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\mybatis\spring\boot\mybatis-spring-boot-starter\2.0.1\mybatis-spring-boot-starter-2.0.1.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\boot\spring-boot-starter-jdbc\2.1.5.RELEASE\spring-boot-starter-jdbc-2.1.5.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\com\zaxxer\HikariCP\3.2.0\HikariCP-3.2.0.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-jdbc\5.1.7.RELEASE\spring-jdbc-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-tx\5.1.7.RELEASE\spring-tx-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\mybatis\spring\boot\mybatis-spring-boot-autoconfigure\2.0.1\mybatis-spring-boot-autoconfigure-2.0.1.jar;D:\Software\apache-maven-3.3.9\repo\org\mybatis\mybatis\3.5.1\mybatis-3.5.1.jar;D:\Software\apache-maven-3.3.9\repo\org\mybatis\mybatis-spring\2.0.1\mybatis-spring-2.0.1.jar;D:\Software\apache-maven-3.3.9\repo\mysql\mysql-connector-java\8.0.16\mysql-connector-java-8.0.16.jar;D:\Software\apache-maven-3.3.9\repo\org\slf4j\slf4j-api\1.7.26\slf4j-api-1.7.26.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-core\5.1.7.RELEASE\spring-core-5.1.7.RELEASE.jar;D:\Software\apache-maven-3.3.9\repo\org\springframework\spring-jcl\5.1.7.RELEASE\spring-jcl-5.1.7.RELEASE.jar;D:\softinstall\IntelliJ IDEA 15.0.1\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain com.example.demo0531.DemoApplication --spring.output.ansi.enabled=always

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.5.RELEASE)

2019-05-31 14:24:31.814  INFO 14152 --- [           main] com.example.demo0531.DemoApplication     : Starting DemoApplication on zhangs378 with PID 14152 (D:\java_project\06\target\classes started by zhangs378 in D:\java_project\06)
2019-05-31 14:24:31.818  INFO 14152 --- [           main] com.example.demo0531.DemoApplication     : No active profile set, falling back to default profiles: default
2019-05-31 14:24:32.456  WARN 14152 --- [           main] o.m.s.mapper.ClassPathMapperScanner      : No MyBatis mapper was found in '[com.example.demo0531]' package. Please check your configuration.
2019-05-31 14:24:33.378  INFO 14152 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2019-05-31 14:24:33.406  INFO 14152 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2019-05-31 14:24:33.406  INFO 14152 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.19]
2019-05-31 14:24:33.535  INFO 14152 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2019-05-31 14:24:33.535  INFO 14152 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1670 ms
2019-05-31 14:24:33.778  INFO 14152 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2019-05-31 14:24:33.898  WARN 14152 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Failed to determine a suitable driver class
2019-05-31 14:24:33.898  INFO 14152 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
2019-05-31 14:24:33.900  INFO 14152 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2019-05-31 14:24:33.915  INFO 14152 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2019-05-31 14:24:33.916 ERROR 14152 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
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).

Process finished with exit code 1
 

然后，我在网上搜了解决办法是：在启动类上添加注解 @EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class}) 。解决了。

他说是因为：

spring boot 会默认加载

1	org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration 这个类

DataSourceAutoConfiguration类使用了@Configuration注解向spring注入了dataSource bean。因为工程中没有关于dataSource相关的配置信息，当spring创建dataSource bean因缺少相关的信息就会报错。

但是，对于这个解释，我现在还不是太明白，加油啊！~