记录项目中遇见的几个常见异常

org.springframework.beans.factory.BeanCreationException && java.lang.IllegalStateException

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerAdapter' defined in class path resource [org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration$EnableWebFluxConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Failed to introspect Class [com.hmall.common.advice.CommonExceptionAdvice] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@2437c6dc]
Caused by: java.lang.IllegalStateException: Failed to introspect Class [com.hmall.common.advice.CommonExceptionAdvice] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@2437c6dc]

原因：

在全局异常处理器类上加上@ConditionalOnClass(DispatcherServlet.class)

目的是为了，只有Web环境的微服务当前配置才会被激活

com.rabbitmq.client.AuthenticationFailureException

Caused by: com.rabbitmq.client.AuthenticationFailureException: ACCESS_REFUSED - Login was refused using authentication mechanism PLAIN. For details see the broker logfile.

解决：

检查RabbitMQ的用户名和密码和连接配置

java.sql.SQLNonTransientConnectionException

com.alibaba.druid.pool.DruidDataSource : create connection SQLException, url: jdbc:mysql://localhost:3306/tlias?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai, errorCode 0, state 08001 java.sql.SQLNonTransientConnectionException: Public Key Retrieval is not allowed

原因：

具体原因未知...，可能，SpringBoot运行过程中，mysql服务重新启动了，导致报错

解决：

cmd控制台，开启mysql服务，输入用户名和密码连接mysql，重启SprintBoot项目

1. 启动mysql服务 net start mysql
2. 登录mysql mysql -u root -p
3. 登出mysql exit

com.mysql.cj.jdbc.exceptions.CommunicationsException

com.alibaba.druid.pool.DruidDataSource : create connection SQLException, url: jdbc:mysql://localhost:3306/tlias?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai, errorCode 0, state 08S01
com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

原因：

SpringBoot运行过程中，mysql服务停止，导致报错

Caused by: com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

原因：

与 MySQL 服务器的通信出现了问题

org.apache.ibatis.exceptions.TooManyResultsException

Caused by: org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2

原因：

你调用了一个应该返回单个结果的方法（如selectOne()），但查询结果有多于一个的记录。这通常是因为你的查询条件匹配到了多条记录，而你的代码却期望只返回一条记录

com.mysql.cj.jdbc.exceptions.MysqlDataTruncation

Caused by: com.mysql.cj.jdbc.exceptions.MysqlDataTruncation: Data truncation: Data too long for column 'name' at row 1

原因：

向MySQL数据库的某个字段插入数据时，如果数据的实际长度超过了该字段定义的最大长度，MySQL就会抛出“Data too long for column”错误

java.sql.SQLIntegrityConstraintViolationException

Caused by: java.sql.SQLIntegrityConstraintViolationException: Column 'name' cannot be null

原因：

提示name字段不能为空，是因为数据库里加了非null约束

java.sql.SQLIntegrityConstraintViolationException

Caused by: java.sql.SQLIntegrityConstraintViolationException: Duplicate entry '411381200202193234' for key 'student.id_number'

原因：

插入数据时，具有唯一约束条件的列值重复了

java.sql.SQLException

Caused by: java.sql.SQLException: Column count doesn't match value count at row 1

原因：

列和值数量不一致

Caused by: java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: YES)

原因：

数据库连接用户名或密码错误

Caused by: java.sql.SQLException: Before start of result set

原因：

ResultSet 中获取数据之前，未调用next()方法

Caused by: java.sql.SQLException: Column 'id_number' not found.

原因：

获取的字段和列名没有匹配到

java.sql.SQLSyntaxErrorException

Caused by: java.sql.SQLSyntaxErrorException: Unknown database 'db'

原因：

找不到db数据库

Caused by: java.sql.SQLSyntaxErrorException: Table 'test84.user' doesn't exist

原因：

名为 test84 的数据库中不存在名为 user 的表。

Caused by: java.sql.SQLSyntaxErrorException: Unknown column 'clazz_id' in 'field list'

原因：

SQL 查询中使用clazz_id作为列，但在数据库中没有找到对应的clazz_id列名