Java SpringMVC访问MySQL数据库的方法

Question

我正在关注 Java SpringMVC tutorial关于访问数据库。按照说明设置好所有内容后，运行命令 mvn spring-boot:run

后出现以下错误

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

Description:

Parameter 0 of constructor in org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration required a bean of type 'javax.sql.DataSource' that could not be found.
        - Bean method 'dataSource' not loaded because @ConditionalOnProperty (spring.datasource.jndi-name) did not find property 'jndi-name'
        - Bean method 'dataSource' not loaded because @ConditionalOnBean (types: org.springframework.boot.jta.XADataSourceWrapper; SearchStrategy: all) did not find any beans


Action:

Consider revisiting the conditions above or defining a bean of type 'javax.sql.DataSource' in your configuration.

[WARNING]
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:527)
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: 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.NoSuchBeanDefinitionException: No qualifying bean of type 'javax.sql.DataSource' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:749)
        at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:189)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1193)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1095)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
        at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:372)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1173)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1067)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
        at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1078)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:857)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
        at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693)
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107)
        at hello.Application.main(Application.java:15)
        ... 6 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'javax.sql.DataSource' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1493)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1104)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1066)
        at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835)
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741)
        ... 34 more

教程页面中的代码与我项目中的代码相匹配。这是我的 src/main/resources/application.properties 文件中的设置。

spring.jpa.hibernate.ddl-auto=update
spring.datasource.url=jdbc:mysql://localhost:3306/java-accessing-db
spring.datasource.username=root
spring.datasource.password=

我对 SpringMVC 框架和 Java 非常陌生。所以我不知道是什么导致了这个问题。我认为我的驱动程序设置不正确或缺少依赖项。

Answer 1

首先在属性文件中添加方言

spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

我现在不知道问题是不是这个问题。我想你只是错过了设置一个 bean。所以检查 DAO 类和资源类，也许你忘记了 @Autowired 其中一些。还要记住 Spring Data 使用存储库检查这里 Working with SQL databases检查这 3 个，我相信您会找到的，我很乐意提供帮助。这是您在 JEE Perspective 中获得的 Spring-Elements 树 如果您可以发布此内容，将会有所帮助。