无法使用MySQL连接Spring Boot

Question

我创建了一个名为: books_management_system的数据库，然后用spring book app生成四列的表，butI不能连接MySQL和Spring Boot App，这里是applicaton.properties文件和pom.xml，我认为xml文件是可以的，但问题可能是在app.properties文件中，请给我帮助

spring.datasource.url=jdbc:mysql://localhost:3306/books_management_system
spring.datasource.username=root
spring.datasource.password=ivana12345
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.database-platform = org.hibernate.dialect.MySQL5Dialect
spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto = update

<?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>2.5.4</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.books</groupId>
    <artifactId>springboot-books-management-system</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-books-management-system</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>16</java.version>
    </properties>
    <dependencies>
        <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>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
<!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-data-jpa -->

        <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>

</project>

Answer 1

在你的新帖子中，你现在没有任何驱动程序类名。我已经创建了一个运行良好的示例。-->

#database properties
spring.datasource.url=jdbc:mysql://localhost:3306/smartcontactmanager
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.jpa.hibernate.ddl-auto=update

我使用过mysql 8.0.21版

Answer 2

使用这个

spring.database.driverClassName= com.mysql.jdbc.Driver

而不是

spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

还有add这个dependency

 <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.14</version>
    </dependency>

而不是

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>

Answer 3

我建议您首先说明MySQL依赖项的版本。这是因为驱动程序包名称根据版本的不同而不同。在8.0.14之后，包名变为com.mysql.cj.jdbc.Driver，其下为com.mysql.jdbc.Driver。所以你应该在你的pom中添加版本。因为版本可能不是来自父级。同时，为了安全起见，请尝试将版本添加到所有依赖项中。