java - 尝试运行 Spring boot 应用程序时出错。使用名称创建 bean 时出错

Question

我目前正在学习 John Thompson Spring 类(class) Spring Framework 5:初学者到大师。尝试构建第一个基本应用程序，但我不断收到错误。我尝试在网上搜索解决方案，但没有任何效果。

这是 pom.xml 代码:

http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.mycompany.firstspringproject</groupId>
<artifactId>first-spring-project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>first-spring-project</name>
<description>First project for Spring Boot</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

整个文件是根据我在 Spring Initializr 中选择的内容生成的。我不断收到的错误是:

 [INFO] ------------------------------------------------------------------------
 [INFO] BUILD FAILURE
 [INFO] ------------------------------------------------------------------------
 [INFO] Total time: 4.648 s
 [INFO] Finished at: 2018-01-20T21:20:05+01:00
 [INFO] Final Memory: 38M/378M
 [INFO] ------------------------------------------------------------------------
 [ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-          plugin:1.5.9.RELEASE:run (default-cli) on project first-spring-project: An      exception occurred while running. null: InvocationTargetException: 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). -> [Help 1]
 [ERROR]
 [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
 [ERROR] Re-run Maven using the -X switch to enable full debug logging.
 [ERROR]
 [ERROR] For more information about the errors and possible solutions, please read the following articles:
 [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

如果您需要更多详细信息，请询问。我会尽力交付。

Answer 1

您最终得到的错误是这样的:

Cannot determine embedded database driver class for database type NONE.

According to the documentation ，您需要定义一些属性，以便 Spring 知道您想要与哪个数据库通信。 Spring Boot 对此没有开箱即用的默认设置。

您需要在 application.properties 中定义的示例:

spring.datasource.url=jdbc:mysql://localhost/test
spring.datasource.username=dbuser
spring.datasource.password=dbpass
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

驱动程序、URL 和凭据将根据您托管数据库的位置及其类型而变化。完整的属性列表可以找到 in the Appendix 。如果需要，您可以嵌入 H2 数据库，而不是像上面的示例那样使用 MySql。