这个问题要从“
java.io.IOException: Server returned HTTP response code: 403 for URL: http://start.spring.io
”错误说起，eclipse 创建 spring boot 项目 遇到错误：java.io.IOException: Server returned HTTP response code: 403 for URL: http://start.spring.io然后就在网页上创建项目下载，新建Maven工程，修改Pom.xml 文件……
完整错误信息如下：
2017-12-29 17:28:51.149 INFO 4429 --- [ main] com.wanyu.fams.App : Starting App on avenMac.local with PID 4429 (/Users/aven/Documents/workspace/fams/fams/target/classes started by aven in /Users/aven/Documents/workspace/fams/fams)
2017-12-29 17:28:51.153 INFO 4429 --- [ main] com.wanyu.fams.App : No active profile set, falling back to default profiles: default
2017-12-29 17:28:51.228 INFO 4429 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4e7912d8: startup date [Fri Dec 29 17:28:51 CST 2017]; root of context hierarchy
2017-12-29 17:28:52.062 WARN 4429 --- [ main] o.m.s.mapper.ClassPathMapperScanner : No MyBatis mapper was found in '[com.wanyu.fams]' package. Please check your configuration.
2017-12-29 17:28:53.358 INFO 4429 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-12-29 17:28:53.384 INFO 4429 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2017-12-29 17:28:53.386 INFO 4429 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.23
2017-12-29 17:28:53.564 INFO 4429 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2017-12-29 17:28:53.564 INFO 4429 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2341 ms
2017-12-29 17:28:53.904 INFO 4429 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2017-12-29 17:28:53.913 INFO 4429 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-12-29 17:28:53.914 INFO 4429 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-12-29 17:28:53.915 INFO 4429 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-12-29 17:28:53.915 INFO 4429 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2017-12-29 17:28:54.580 INFO 4429 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4e7912d8: startup date [Fri Dec 29 17:28:51 CST 2017]; root of context hierarchy
2017-12-29 17:28:54.725 INFO 4429 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2017-12-29 17:28:54.727 INFO 4429 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2017-12-29 17:28:54.805 INFO 4429 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-12-29 17:28:54.805 INFO 4429 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-12-29 17:28:54.929 INFO 4429 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-12-29 17:28:55.030 WARN 4429 --- [ main] 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).
2017-12-29 17:28:55.034 INFO 4429 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2017-12-29 17:28:55.064 INFO 4429 --- [ main] utoConfigurationReportLoggingInitializer :
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2017-12-29 17:28:55.072 ERROR 4429 --- [ 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).分析原因：
这是因为spring boot 会默认加载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。
解决方案一：
在类定义上增加@EnableAutoConfiguration(exclude={DataSourceAutoConfiguration.class})的注解。
解决方案二：
在 application.properties 文件中添加数据库配置，例如：
#spring.datasource.type=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://your DataBase Server IP:3306/DatabaseName?useUnicode=true&zeroDateTimeBehavior=convertToNull&autoReconnect=truespring.datasource.username=username
spring.datasource.password=password注意，如果使用：
spring.datasource.type=com.mysql.jdbc.Driver还需要在 pom.xml 中添加依赖：
<!-- 导入Mysql数据库链接jar包 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.41</version>
</dependency>spring.datasource.type 需要指定的是 dataSource 实现类，不是 Driver。
Driver 是这样写的：
spring.datasource.driver-class-name=com.mysql.jdbc.Driver那么这个怎么填写呢？
1、不写！Spring Boot 默认的数据源是 org.apache.tomcat.jdbc.pool.DataSource
2、在实际开发中我们可能需要使用我们比较熟悉的数据源或者性能比比较高的数据源，比如Druid,那么很自然的我们就不能使用默认的数据源，这时候spring.datasource.type就诞生了。spring.datasource.type属性的存在能够使我们快速的指定我们需要的数据源，但是在使用的过程当中还是需要有些需要注意的！
需要注意的是：spring.datasource.type旧的spring boot版本是不能识别的。
（更新于2016年8月20日）：很抱歉的是新版本也废弃了这个属性，配置完之后启动就会报错，所以现在知道的情况是1.2版本不支持，1.3版本支持，1.4.0版本不支持。具体信息可以看链接：http://stackoverflow.com/questions/39032368/not-able-to-set-spring-datasource-type-in-spring-boot-1-4 ）
（更新于2016年9月24日）：spring boot 1.4.1重新支持了spring.datasource.type属性，从1.4.0的启动报异常到1.4.1支持，个人觉得这个应该是官方在升级的时候，影响到了spring.datasource.type属性的使用。不管怎么样，希望spring boot做的越来越好。
你还可以使用 application.yml 文件
写法更直观哦，类似 Python 的强缩进：
#application.yml
spring:
datasource:
name: test
url: jdbc:mysql://192.168.1.168:3306/test
username: root
password:
# 使用druid数据源
type: com.alibaba.druid.pool.DruidDataSource
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 1
maxWait: 60000
minIdle: 1
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20