使用Spring Boot以来，遇到和解决过好几次不同的项目启动问题，大多数事故起于错误的配置和依赖。因此，本文用于汇总这些问题，以及提供相应的解决方案，帮助大家更快的定位和排除故障。

1. Unregistering JMX-exposed beans on shutdown

  项目中没有添加spring-boot-starter-web模块依赖，在启动 Application 运行过程中会出现这个错误。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v1.5.11.RELEASE)

2018-05-02 18:32:49.445  INFO 33160 --- [           main] cn.mariojd.demo.DemoApplication          : Starting DemoApplication on Mario with PID 33160 (started by jd in D:\IntelliJ IDEA\projects\test)
2018-05-02 18:32:49.451  INFO 33160 --- [           main] cn.mariojd.demo.DemoApplication          : No active profile set, falling back to default profiles: default
2018-05-02 18:32:49.542  INFO 33160 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@17211155: startup date [Wed May 02 18:32:49 CST 2018]; root of context hierarchy
2018-05-02 18:32:50.115  INFO 33160 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-05-02 18:32:50.128  INFO 33160 --- [           main] cn.mariojd.demo.DemoApplication          : Started DemoApplication in 1.01 seconds (JVM running for 1.83)
... end SpringApplication.run()
2018-05-02 18:32:50.129  INFO 33160 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@17211155: startup date [Wed May 02 18:32:49 CST 2018]; root of context hierarchy
2018-05-02 18:32:50.130  INFO 33160 --- [       Thread-2] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown

  解决方案，引入spring-boot-starter-web模块

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

  网上大多数的解决方案是通过添加spring-boot-starter-tomcat依赖来解决，但实测证明此方法不可行。

2. Cannot determine embedded database driver class for database type NONE

  项目中添加了spring-boot-starter-data-jpa模块依赖，而且没有配置数据源连接信息的情况下，启动 Application 过程中会出现该错误，原因是Spring Boot在启动时会自动注入数据源和配置JPA。

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v1.5.11.RELEASE)

2018-05-02 19:49:13.640  INFO 37652 --- [           main] cn.mariojd.demo.DemoApplication          : Starting DemoApplication on Mario with PID 37652 (started by jd in D:\IntelliJ IDEA\projects\test)
2018-05-02 19:49:13.643  INFO 37652 --- [           main] cn.mariojd.demo.DemoApplication          : No active profile set, falling back to default profiles: default
2018-05-02 19:49:13.692  INFO 37652 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@62fdb4a6: startup date [Wed May 02 19:49:13 CST 2018]; root of context hierarchy
2018-05-02 19:49:15.150  INFO 37652 --- [           main] trationDelegate$BeanPostProcessorChecker : Bean 'org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration' of type [org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration$$EnhancerBySpringCGLIB$$4ad697b] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-05-02 19:49:15.433  INFO 37652 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2018-05-02 19:49:15.460  INFO 37652 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-05-02 19:49:15.461  INFO 37652 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
2018-05-02 19:49:15.564  INFO 37652 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-05-02 19:49:15.564  INFO 37652 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1876 ms
2018-05-02 19:49:15.679  INFO 37652 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2018-05-02 19:49:15.682  INFO 37652 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-05-02 19:49:15.682  INFO 37652 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-05-02 19:49:15.682  INFO 37652 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-05-02 19:49:15.683  INFO 37652 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-05-02 19:49:15.717  WARN 37652 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Tomcat.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.tomcat.jdbc.pool.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath. If you have database settings to be loaded from a particular profile you may need to active it (no profiles are currently active).
2018-05-02 19:49:15.719  INFO 37652 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2018-05-02 19:49:15.765  INFO 37652 --- [           main] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2018-05-02 19:49:15.791 ERROR 37652 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

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

Description:

Cannot determine embedded database driver class for database type NONE

Action:

If you want an embedded database please put a supported one on the classpath. If you have database settings to be loaded from a particular profile you may need to active it (no profiles are currently active).


Process finished with exit code 1

• 解决方案1，移除spring-boot-starter-data-jpa模块依赖；
• 解决方案2，将启动类注解@SpringBootApplication修改如下；

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class,DataSourceTransactionManagerAutoConfiguration.class, HibernateJpaAutoConfiguration.class})

• 解决方案3，在配置文件中添加数据库连接信息。

spring:
  datasource:
    url: xxx
    username: xxx
    password: xxx