最近在学习使用spring boot。使用maven创建好工程，只引用需要用到的spring boot相关的jar包,除此之外没有任何的配置。

写了一个最简单的例子，如下所示:

 package com.torlight;

 import org.springframework.boot.SpringApplication;

 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

 import org.springframework.boot.autoconfigure.SpringBootApplication;

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

 import org.springframework.context.ApplicationContext;

 import org.springframework.context.ConfigurableApplicationContext;

 /**

  * @since 2017.05.06

  * @author acer

  *

  */

 @SpringBootApplication

 public class Application {

     public static void main(String[] args) {

         ApplicationContext appctx= SpringApplication.run(Application.class,args);

         System.out.println("appctx.getBeanDefinitionCount="+appctx.getBeanDefinitionCount());

         try {

             ((ConfigurableApplicationContext)appctx).close();

         } catch (Exception e) { /*ignore*/ }

     }

 }

运行程序后，控制台输出错误日志：

017-05-06 22:44:18.868 WARN 41648 --- [ restartedMain] ationConfigEmbeddedWebApplicationContext : 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$Tomcat.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.apache.tomcat.jdbc.pool.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$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).
2017-05-06 22:44:18.871 INFO 41648 --- [ restartedMain] o.apache.catalina.core.StandardService : Stopping service Tomcat
2017-05-06 22:44:18.902 INFO 41648 --- [ restartedMain] utoConfigurationReportLoggingInitializer :

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-05-06 22:44:18.907 ERROR 41648 --- [ restartedMain] 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).

这是因为spring boot默认会加载org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration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。

因为我仅仅只是使用spring boot来写一些很简单的例子来学习它，在Application类上增加@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})

阻止spring boot自动注入dataSource bean

 package com.torlight;

 import org.springframework.boot.SpringApplication;

 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;

 import org.springframework.boot.autoconfigure.SpringBootApplication;

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

 import org.springframework.context.ApplicationContext;

 import org.springframework.context.ConfigurableApplicationContext;

 /**

  * @since 2017.05.06

  * @author acer

  *

  */

 @SpringBootApplication
@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})
 public class Application {

     public static void main(String[] args) {

         ApplicationContext appctx= SpringApplication.run(Application.class,args);

         System.out.println("appctx.getBeanDefinitionCount="+appctx.getBeanDefinitionCount());

         try {

             ((ConfigurableApplicationContext)appctx).close();

         } catch (Exception e) { /*ignore*/ }

     }

 }