maven 错误的解决方法

首先，Intellij IDEA中是有内置maven 的，可以直接使用。

但是如果是使用系统内置的maven的话，第一次使用maven创建的项目会出现整版的错误，例如下面的，点击各种下载和刷新，都没有任何反应。

只会提示出现：Cannot resolve plugin org.springframework.boot:spring-boot-maven-plugin:2.2.6.RELEASE 等错误信息，
这种明显是maven的库的错误，不是项目需要的jar丢失，而是mavne的库丢失

这个时候我们需要点击

选中下面的全部点击安装，那你的Plugins 就能显示正常了

那么 Dependencies 中的错误该如何点击呢？
例如：
在这里插入图片描述

如果出现jar库警告，但是本地maven库之中又存在该资源文档。而且删除了重新下载还是出现红色警告。

那么主要原因在于该版本maven之中相关资源库其实还没有同步，建议降低你的spring-boot-starter 的版本；

降低该版本号，具体有多少版本，可以通过https://mvnrepository.com/ 网址进行查询，输入spring boot starter 进行搜索

其实这个红色错误，一般不会影响到你的项目的运行。

修改完成之后：

就是正常状态下了。没有警告和错误

启动时报错Failed to determine a suitable driver class 解决方法

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 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::       (v2.1.13.RELEASE)

2020-04-08 18:17:45.752  INFO 30384 --- [           main] c.i.s.whiteboard.WhiteboardApplication   : Starting WhiteboardApplication on DZ-196 with PID 30384 (D:\SVNProject\WebServer\whiteboard\target\classes started by xxxx in D:\SVNProject\WebServer\whiteboard)
2020-04-08 18:17:45.758  INFO 30384 --- [           main] c.i.s.whiteboard.WhiteboardApplication   : No active profile set, falling back to default profiles: default
2020-04-08 18:17:47.767  WARN 30384 --- [           main] o.m.s.mapper.ClassPathMapperScanner      : No MyBatis mapper was found in '[com.irtouch.server.whiteboard]' package. Please check your configuration.
2020-04-08 18:17:48.816  INFO 30384 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2020-04-08 18:17:48.863  INFO 30384 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2020-04-08 18:17:48.864  INFO 30384 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.31]
2020-04-08 18:17:49.227  INFO 30384 --- [           main] o.a.c.c.C.[.[localhost].[/whiteboard]    : Initializing Spring embedded WebApplicationContext
2020-04-08 18:17:49.228  INFO 30384 --- [           main] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 3383 ms
2020-04-08 18:17:49.686  INFO 30384 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Initializing ExecutorService 'applicationTaskExecutor'
2020-04-08 18:17:49.814  INFO 30384 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page template: index
2020-04-08 18:17:49.955  WARN 30384 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: 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
2020-04-08 18:17:49.956  INFO 30384 --- [           main] o.s.s.concurrent.ThreadPoolTaskExecutor  : Shutting down ExecutorService 'applicationTaskExecutor'
2020-04-08 18:17:49.963  INFO 30384 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2020-04-08 18:17:49.985  INFO 30384 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-04-08 18:17:50.000 ERROR 30384 --- [           main] 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).

[0x7FF9CD166230] ANOMALY: meaningless REX prefix used

Process finished with exit code 1

其实主要原因在于数据库配置，无法实例化，造成springboot 无法启动

因为创建项目的时候，引用了JDBC库，才会出现的问题。需要主动将jdbc相关配置信息添加进去，才能成功

解决方法：
application中先配置DataSource基本信息

首先确认 resources 目录下的application文件的后缀，直接rename 修改后缀为 yml

在这里插入图片描述

然后在 application.yml 文件之中填写下面的代码。

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/test
    name: test
    username: wevServer
    password: webServer2020
    driver-class-name: com.mysql.cj.jdbc.Driver

关键是driver-class-name 配置了jdbc加载的驱动。

运行时就能够正常访问了

如果你数据库都还不存在，未添加，那么建议pom之中，将jdbc相关的库全部注释即可

请注意，如果出现下面的警告错误

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `
com.mysql.cj.jdbc.Driver'.
 The driver is automatically 
 registered via the SPI and manual 
 loading of the driver class is generally unnecessary.

在这里插入图片描述