11.4 数据库层配置

上面的模板工程，我们来直接运行main函数，会发现启动失败，控制台会输出如下报错信息：

BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]
...
***************************
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).

因为我们还没有配置数据源。我们先在MySQL中新建一个schema：

CREATE SCHEMA `blog` DEFAULT CHARACTER SET utf8 ;

11.4.1 配置数据源

接着，我们在配置文件application.properties中配置MySQL数据源：
```# datasource# datasource: unicode编码的支持，设定为utf-8
spring.datasource.url=jdbc//localhost:3306/blog?zeroDateTimeBehavior=convertToNull&characterEncoding=utf8&characterSetResults=utf8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.testWhileIdle=true
spring.datasource.validationQuery=SELECT 1

其中，spring.datasource.url 中，为了支持中文的正确显示（防止出现中文乱码），我们需要设置一下编码。
数据库ORM（对象关系映射）层，我们使用spring-data-jpa ：

spring.jpa.database=MYSQL
spring.jpa.show-sql=true# Hibernate ddl auto (create, create-drop, update)
spring.jpa.hibernate.ddl-auto=update# Naming strategy
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.ImprovedNamingStrategy
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

再次运行启动类，控制台输出启动日志：

…

                    _  __     _   _ _
                   | |/ /    | | | (_)          _
                   | ' / ___ | |_| |_ _ __    _| |_
                   |  < / _ \| __| | | '_ \  |_   _|
                   | . \ (_) | |_| | | | | |   |_|
                   |_|\_\___/ \__|_|_|_| |_|
          _____            _             ____              _
         / ____|          (_)           |  _ \            | |
        | (___  _ __  _ __ _ _ __   __ _| |_) | ___   ___ | |_
         \___ \| '_ \| '__| | '_ \ / _` |  _ < / _ \ / _ \| __|
         ____) | |_) | |  | | | | | (_| | |_) | (_) | (_) | |_
        |_____/| .__/|_|  |_|_| |_|\__, |____/ \___/ \___/ \__|
               | |                  __/ |
               |_|                 |___/

2017-07-17 21:10:48.741 INFO 5062 —- [ restartedMain] c.Chapter11KotlinSpringbootApplicationKt : Starting Chapter11KotlinSpringbootApplicationKt on 192.168.1.6 with PID 5062 …
…
2017-07-17 21:19:40.548 INFO 5329 —- [ restartedMain] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit ‘default’
2017-07-17 21:11:03.017 INFO 5062 —- [ restartedMain] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped “{[/application/env || /application/env.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}” onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
…
2017-07-17 21:11:03.026 INFO 5062 —- [ restartedMain] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped “{[/application/beans || /application/beans.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}” onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2017-07-17 21:11:03.028 INFO 5062 —- [ restartedMain] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped “{[/application/health || /application/health.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}” onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.HealthMvcEndpoint.invoke(javax.servlet.http.HttpServletRequest,java.security.Principal)
…
2017-07-17 21:11:03.060 INFO 5062 —- [ restartedMain] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped “{[/application/autoconfig || /application/autoconfig.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}” onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
…
2017-07-17 21:11:03.478 INFO 5062 —- [ restartedMain] o.s.ui.freemarker.SpringTemplateLoader : SpringTemplateLoader for FreeMarker: using resource loader [org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6aab8872: startup date [Mon Jul 17 21:10:48 CST 2017]; root of context hierarchy] and template loader path [classpath:/templates/]
2017-07-17 21:11:03.479 INFO 5062 —- [ restartedMain] o.s.w.s.v.f.FreeMarkerConfigurer : ClassTemplateLoader for Spring macros added to FreeMarker configuration
2017-07-17 21:11:03.520 WARN 5062 —- [ restartedMain] o.s.b.a.f.FreeMarkerAutoConfiguration : Cannot find template location(s): [classpath:/templates/] (please add some templates, check your FreeMarker configuration, or set spring.freemarker.checkTemplateLocation=false)
2017-07-17 21:11:03.713 INFO 5062 —- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2017-07-17 21:11:03.871 INFO 5062 —- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2017-07-17 21:11:03.874 INFO 5062 —- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Bean with name ‘dataSource’ has been autodetected for JMX exposure
2017-07-17 21:11:03.886 INFO 5062 —- [ restartedMain] o.s.j.e.a.AnnotationMBeanExporter : Located MBean ‘dataSource’: registering with JMX server as MBean [com.zaxxer.hikari:name=dataSource,type=HikariDataSource]
2017-07-17 21:11:03.901 INFO 5062 —- [ restartedMain] o.s.c.support.DefaultLifecycleProcessor : Starting beans in phase 0
2017-07-17 21:11:04.232 INFO 5062 —- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8000 (http)
2017-07-17 21:11:04.240 INFO 5062 —- [ restartedMain] c.Chapter11KotlinSpringbootApplicationKt : Started Chapter11KotlinSpringbootApplicationKt in 16.316 seconds (JVM running for 17.68)

```

关于上面的日志，我们通过下面的表格作简要说明：