瑞吉shardingjdbc4.0.0-RC1--＞RC2 读写分离示例错误排查

linux环境：CentOS7.8+mysql5.7.29

idea：jdk1.8+maven3.5

框架：springboot2.4.5 + mybatisplus3.4.2(mybatis-plus-boot-starter)+sharding-jdbc4.0.0-RC2(sharding-jdbc-spring-boot-starter兼容性问题由1改成2)+druid

B站项目视频：黑马2022年的瑞吉外卖，shardingjdbc读写分离案例

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1、数据库连接性问题

错误原因： 数据库连接不上，要么数据库没开，要么访问不了10.0.0.200:3307

INFO 12396 — [ main] com.itheima.Application
ERROR 12396 — [eate-2142450580] com.alibaba.druid.pool.DruidDataSource : create connection SQLException, url: jdbc:mysql://10.0.0.200:3307/rw?characterEncoding=utf-8, errorCode 0, state 08S01

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.
Caused by: java.net.ConnectException: Connection refused: connect

解决思路：1.检查url是否正确 2.mysql是否设置了防火墙 3.数据库是否支持远程访问(本地安装不算)

=============================================================================

2、兼容性问题排查

INFO 13260 — [main] com.itheima.Application : No active profile set, falling back to default profiles: default
ERROR 13260 — [main] o.s.boot.SpringApplication : Application run failed

java.lang.IllegalArgumentException: Unresolvable class definition for class [org.apache.shardingsphere.shardingjdbc.spring.boot.sharding.SpringBootShardingRuleConfigurationProperties]
Caused by: java.lang.NoClassDefFoundError: org/apache/shardingsphere/core/yaml/config/sharding/YamlShardingRuleConfiguration
at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_381]
at java.lang.ClassLoader.defineClass(ClassLoader.java:756) ~[na:1.8.0_381]

Caused by: java.lang.ClassNotFoundException: org.apache.shardingsphere.core.yaml.config.sharding.YamlShardingRuleConfiguration
at java.net.URLClassLoader.findClass(URLClassLoader.java:387) ~[na:1.8.0_381]

YamlShardingRuleConfiguration有该类的话是可以打开的，但是报红了且不能打开

提示还是不够明显，加入以下坐标帮助查询错误信息

    org.apache.shardingsphere
    sharding-core-common
    4.0.0-RC1

清除缓存maven clean+idea Invalidate Cache：
再次运行

Error starting ApplicationContext. To display the conditions report re-run your application with ‘debug’ enabled.
ERROR 17756 — [ main] o.s.boot.SpringApplication : Application run failed

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘userController’: Unsatisfied dependency expressed through field ‘dataSource’; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘dataSource’ defined in class path resource [org/apache/shardingsphere/shardingjdbc/spring/boot/SpringBootConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method ‘dataSource’ threw exception; nested exception is java.lang.NoClassDefFoundError: org/apache/shardingsphere/shardingjdbc/api/MasterSlaveDataSourceFactory

Caused by: java.lang.ClassNotFoundException: org.apache.shardingsphere.shardingjdbc.api.MasterSlaveDataSourceFactory
at java.net.URLClassLoader.findClass(URLClassLoader.java:387) ~[na:1.8.0_381]
at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[na:1.8.0_381]

在查看SpringBootConfiguration.class上面import导入的api都报红了

import org.apache.shardingsphere.shardingjdbc.api.EncryptDataSourceFactory;
import org.apache.shardingsphere.shardingjdbc.api.MasterSlaveDataSourceFactory;
import org.apache.shardingsphere.shardingjdbc.api.ShardingDataSourceFactory;

结论：说明springboot2.4.5应该是不兼容shardingjdbc4.0.0RC1的

解决方法尝试：shardingjdbc4.0.0RC1升级到shardingjdbc4.0.0RC2

思路：再次查看import导入的api是正常且不报红，说明springboot2.4.5兼容shardingjdbc4.0.0RC2，可以继续往下搞

不兼容就没有必要继续

清除缓存maven clean+idea Invalidate Cache：

再次运行

WARN 9112 — [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘userController’: Unsatisfied dependency expressed through field ‘dataSource’; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘dataSource’ defined in class path resource [com/alibaba/druid/spring/boot/autoconfigure/DruidDataSourceAutoConfigure.class]: Invocation of init method failed; nested exception is org.springframework.boot.autoconfigure.jdbc.DataSourceProperties$DataSourceBeanCreationException: Failed to determine a suitable driver class

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).

根据提示
查看com/alibaba/druid/spring/boot/autoconfigure/DruidDataSourceAutoConfigure.class类

这个网友给了一段注释思路：https://blog.csdn.net/evalsys/article/details/107165308
非常感谢
不然真的淦，我查的没有注释

也就是说根据spring.datasource.druid或者spring.datasource查找jdbc属性是找不到的，

因为我们yml文件配置结构是spring.shardingsphere.datasource

解决方式1：如果想继续用druid-spring-boot-starter，则在启动类上排除druid自动配置

@SpringBootApplication(exclude = {DruidDataSourceAutoConfigure.class})

解决方式2：如果不想更改启动类，则修改pom坐标

com.alibaba druid-spring-boot-starter 1.1.23 改为 com.alibaba druid 1.1.23

我选择更改坐标

    4.0.0
    
        org.springframework.boot
        spring-boot-starter-parent
        2.4.5
        
    
    com.cctv
    rw_demo
    1.0-SNAPSHOT
    
        1.8
    
    
        
            org.apache.shardingsphere
            sharding-jdbc-spring-boot-starter
            4.0.0-RC2
        
        
            org.apache.shardingsphere
            sharding-core-common
            4.0.0-RC2
        
        
            org.springframework.boot
            spring-boot-starter-web
            compile
        
        
            org.projectlombok
            lombok
            1.18.20
        
        
            com.alibaba
            fastjson
            1.2.76
        
        
            commons-lang
            commons-lang
            2.6
        
        
            mysql
            mysql-connector-java
            runtime
        
        
            com.baomidou
            mybatis-plus-boot-starter
            3.4.2
        
        
            com.alibaba
            druid
            1.1.23
        
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                2.4.5
            
        
    

原demo+修改后demo链接：https://pan.baidu.com/s/1sy0V3oFh6umIBLAcBBx1Kg?pwd=1234
提取码：1234

3、总结

①问题描述：2022年出的瑞吉外卖项目shardingjdbc4.0.0-RC1有依赖冲突问题，有类未实现，导致无法正常创建数据源，运行失败

②解决方法
解决方法1:（推荐，亲测可行）

• 升级shardingjdbc，把坐标改成RC2
• 把druid-spring-boot-starter改成druid
• maven clean + Invalidate Cache（不做该步骤可能有缓存问题）

解决方法2：

• 升级shardingjdbc，把坐标改成RC2
• 不改druid，还是使用druid-spring-boot-starter，
  在启动类加上@SpringBootApplication(exclude = {DruidDataSourceAutoConfigure.class})
• maven clean + Invalidate Cache（不做该步骤可能有缓存问题）

慢悠悠搞了三天，很淦
觉得有帮助的老铁，我允许你给个小赞赞鼓励一下!
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