SpringBoot项目无法启动，提示Failed to configure a DataSource: 'url' attribute is not specified如何解决？

Question

Eclipse+SpringBoot+MyBatis，死活无法启动。百度了很久，尝试各种办法误解解决。console提示如下：

08:58:11.576 [Thread-2] DEBUG org.springframework.boot.devtools.restart.classloader.RestartClassLoader - Created RestartClassLoader org.springframework.boot.devtools.restart.classloader.RestartClassLoader@4177cebd

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v2.7.9)

2023-03-17 08:58:12.220  INFO 13896 --- [  restartedMain] c.e.redisdemo.RedisDemoApplication       : Starting RedisDemoApplication using Java 1.8.0_351 on DESKTOP-OQ55J3D with PID 13896 (D:\MyData\JavaData\WorkSpace\SpringToolSuit\redis-demo\target\classes started by luqing in D:\MyData\JavaData\WorkSpace\SpringToolSuit\redis-demo)
2023-03-17 08:58:12.223  INFO 13896 --- [  restartedMain] c.e.redisdemo.RedisDemoApplication       : No active profile set, falling back to 1 default profile: "default"
2023-03-17 08:58:12.335  INFO 13896 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-03-17 08:58:12.336  INFO 13896 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-03-17 08:58:13.990  INFO 13896 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-03-17 08:58:13.992  INFO 13896 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : Loaded Apache Tomcat Native library [1.2.36] using APR version [1.7.2].
2023-03-17 08:58:13.993  INFO 13896 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true], UDS [true].
2023-03-17 08:58:13.993  INFO 13896 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : APR/OpenSSL configuration: useAprConnector [false], useOpenSSL [true]
2023-03-17 08:58:13.997  INFO 13896 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1t  7 Feb 2023]
2023-03-17 08:58:14.013  INFO 13896 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-03-17 08:58:14.013  INFO 13896 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.71]
2023-03-17 08:58:14.131  INFO 13896 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-03-17 08:58:14.131  INFO 13896 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1794 ms
2023-03-17 08:58:14.301  WARN 13896 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cityController': Unsatisfied dependency expressed through field 'cityMapper'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'cityMapper' defined in file [D:\MyData\JavaData\WorkSpace\SpringToolSuit\redis-demo\target\classes\com\example\redisdemo\dao\CityMapper.class]: Unsatisfied dependency expressed through bean property 'sqlSessionFactory'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'sqlSessionFactory' defined in class path resource [org/mybatis/spring/boot/autoconfigure/MybatisAutoConfiguration.class]: Unsatisfied dependency expressed through method 'sqlSessionFactory' 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$Hikari.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Failed to determine a suitable driver class
2023-03-17 08:58:14.308  INFO 13896 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2023-03-17 08:58:14.342  INFO 13896 --- [  restartedMain] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2023-03-17 08:58:14.392 ERROR 13896 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

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

Description:

Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.

Reason: Failed to determine a suitable driver class


Action:

Consider the following:
    If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
    If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).

POM文件如下

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.9</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>redis-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>redis-demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </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>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>
</project>

application.properties文件如下

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/world
spring.datasource.username=root
spring.datasource.password=123456

mybatis.mapper-locations=classpath:/mapper/*.xml

Answer 1

原因在于

<resource>
    <directory>src/main/resources</directory>
    <includes>
        <include>**/*.xml</include>
        <!-- 加上这个就行了 -->
        <include>*.properties</include>
    </includes>
    <filtering>true</filtering>
</resource>

application.properties也位于src/main/resources下面。但是你这个配置仅处理*.xml结尾的文件，将配置文件忽略了。

或者你也可以直接删除resources相关的配置，理论上不用处理dao.xml的。

---

本文参与了SegmentFault 思否面试闯关挑战赛，欢迎正在阅读的你也加入。