Spring Boot Data JPA无法连接到MySQL数据库。

Question

我试着使用spring-boot-starter-data-jpa和Hibernate连接MySQL，参考了这个例子，但是出现以下错误：

...
2016-07-28 13:20:49.021 ERROR 7765 --- [main] o.s.boot.SpringApplication : 应用程序启动失败 org.springframework.beans.factory.BeanCreationException: 创建bean "org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration"时出错，注入的自动装配依赖项失败。嵌套异常信息为：org.springframework.beans.factory.BeanCreationException: 注入字段javax.sql.DataSource org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.dataSource失败，嵌套异常信息为：org.springframework.beans.factory.BeanCreationException: 创建bean 'dataSource'时出错，定义在类路径资源[org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration$NonEmbeddedConfiguration.class]中。通过工厂方法实例化Bean失败；嵌套异常信息为：org.springframework.beans.BeanInstantiationException: 实例化[javax.sql.DataSource]失败，工厂方法'dataSource'抛出异常；嵌套异常信息为：org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: 无法确定嵌入式数据库驱动程序类的数据库类型NONE。如果您想使用嵌入式数据库，请将支持的嵌入式数据库放在类路径上。如果您有要从特定配置文件加载的数据库设置，请激活该配置文件（目前没有配置文件处于激活状态）

...

应用程序属性:

    # DataSource settings: set here your own configurations for the database 
# connection. In this example we have "netgloo_blog" as database name and 
# "root" as username and password.
spring.datasource.url = jdbc:mysql://localhost:3306/db
spring.datasource.username = db
spring.datasource.password = pass

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

# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle = true
spring.datasource.validationQuery = SELECT 1

# Show or not log for each sql query
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

# Use spring.jpa.properties.* for Hibernate native properties (the prefix is
# stripped before adding them to the entity manager)

# The SQL dialect makes Hibernate generate better SQL for the chosen database
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

Eclipse中的项目结构：

build.gradle文件:

 buildscript {
  repositories {
        mavenCentral()
  }
  dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-  plugin:1.3.6.RELEASE")
  }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'spring-boot'

jar {
    baseName = 'gs-accessing-data-jpa'
    version =  '0.1.0'
}

repositories {
    mavenCentral()
    maven { url "https://repository.jboss.org/nexus/content/repositories/releases" }
}

sourceCompatibility = 1.8
targetCompatibility = 1.8

dependencies {
    compile("org.springframework.boot:spring-boot-starter-data-jpa")
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version: '1.3.6.RELEASE'
    compile group: 'mysql', name: 'mysql-connector-java', version: '6.0.3' 

   //also tried

    runtime group: 'mysql', name: 'mysql-connector-java', version: '6.0.3' 
    runtime "org.apache.tomcat:tomcat-jdbc:7.0.47"

    testCompile("junit:junit")
}

task wrapper(type: Wrapper) {
    gradleVersion = '2.3'
}

- Edgaras Karka

---

我刚刚在Intellij中创建了一个具有相同配置的项目，并且按预期工作。你能否手动启动 ./gradlew bootRun 并查看发生了什么？ - Nonika

依赖项 { 编译("org.springframework.boot:spring-boot-starter-data-jpa") 编译组：'org.springframework.boot'，名称：'spring-boot-starter-web'，版本：'1.3.6.RELEASE' 编译组：'mysql'，名称：'mysql-connector-java'，版本：'6.0.3' 测试编译("junit:junit") }不需要使用diver-class，因为spring-boot会自动从spring.datasource.url中检测到它。 - Nonika

Answer 1

您没有添加驱动程序类

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

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

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

请同时检查这些依赖项

- Pankaj Kumar

Answer 2

你能否在Gradle中添加运行时依赖，而不是编译时依赖于MYSQL Driver jar？

dependencies {
  //compile "mysql:mysql-connector-java:6.0.3"
  runtime "mysql:mysql-connector-java:6.0.3"
  runtime "org.apache.tomcat:tomcat-jdbc:7.0.47"
}

- Ramachandran.A.G

---

我按照你的建议更改了build.gradle文件，但异常仍然存在。请参见帖子。 - Edgaras Karka

Answer 3

你的类路径上是否有数据库驱动程序？ 你是否设置了属性 spring.datasource.driver-class-name？

更多详情请参见 http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-sql.html

- Bartosz Bilicki

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是的，我有mysql驱动程序，请查看build.gradle文件。我在application.properties文件中添加了spring.datasource.driver-class-name=com.mysql.jdbc.Driver这一行。 - Edgaras Karka