springboot + sharding-jdbc + myb

pom.xml

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

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.0</version>
        </dependency>

        <dependency>
            <groupId>org.apache.shardingsphere</groupId>
            <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
            <version>4.0.0-RC1</version>
        </dependency>

这里采用的版本是4.0.0-RC1，经测试
4.0.0-RC2会有分表规则不生交往的情况
4.1.1会有自定义主键生成SPI的问题

配置：

# shardingjdbc分片策略
# 配置数据源，给数据源起名称
spring.shardingsphere.datasource.names=m1
 
# 一个实体类对应两张表，覆盖
spring.main.allow-bean-definition-overriding=true
 
#配置数据源具体内容，包含连接池，驱动，地址，用户名和密码
spring.shardingsphere.datasource.m1.type=com.zaxxer.hikari.HikariDataSource
spring.shardingsphere.datasource.m1.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.m1.jdbc-url=jdbc:mysql://localhost:3306/dbname?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true&zeroDateTimeBehavior=convertToNull
spring.shardingsphere.datasource.m1.username=uuu
spring.shardingsphere.datasource.m1.password=ppp

#指定表分布情况，配置表在哪个数据库里面，表名称都是什么  m1.course_1 , m1.course_2
spring.shardingsphere.sharding.tables.course.actual-data-nodes=m1.course_$->{1..64}
 
# 指定表里面主键生成策略SNOWFLAKE
spring.shardingsphere.sharding.tables.course.key-generator.column=id
spring.shardingsphere.sharding.tables.course.key-generator.type=SNOWFLAKE
 
# 指定分片策略
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=corp_id
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course$->{corp_id % 64 + 1}
 
# 打开sql输出日志
spring.shardingsphere.props.sql.show=true

参考： https://www.jianshu.com/p/a58c3b1abb9a

druid：

spring.shardingsphere.datasource.names=m1
 
spring.main.allow-bean-definition-overriding=true
 
spring.shardingsphere.datasource.m1.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.m1.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.m1.url=jdbc:mysql://localhost:3306/aaa?useUnicode=true&characterEncoding=utf8&autoReconnect=true&allowMultiQueries=true&zeroDateTimeBehavior=convertToNull&useSSL=false

spring.shardingsphere.datasource.m1.username=rrrr
spring.shardingsphere.datasource.m1.password=___rM11xI2Pemzr6EerD4xY1A==___
spring.shardingsphere.datasource.m1.connection-properties=password=___rM11xI2Pemzr6EerD4xY1A==___
spring.shardingsphere.datasource.m1.password-callback-class-name=cn.xxx.ddd.callback.DBPasswordCallback

spring.shardingsphere.sharding.tables.course.actual-data-nodes=m1.course$->{1..64}
 
spring.shardingsphere.sharding.tables.course.key-generator.column=id
spring.shardingsphere.sharding.tables.course.key-generator.type=SNOWFLAKE
 
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=corp_id
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course$->{corp_id % 64 + 1}
 
spring.shardingsphere.props.sql.show=true

自定义主键生成类：

spring.shardingsphere.sharding.tables.t_chat_group.key-generator.column=id
#spring.shardingsphere.sharding.tables.t_chat_group.key-generator.type=SNOWFLAKE
spring.shardingsphere.sharding.tables.t_chat_group.key-generator.type=MyShardingKey

@Data
@Slf4j
public class MyShardingKeyGenerator implements ShardingKeyGenerator {

    private Properties properties;

    @Override
    public Comparable<?> generateKey() {
        try {
            return SnowflakeIdUtils.generateId();
        } catch (Exception e) {
            log.error("生成雪花id出错：{}", e.getMessage());
        }
        return null;
    }

    @Override
    public String getType() {
        return "MyShardingKey";
    }

}

创建目录：META/services
在其下建文件：org.apache.shardingsphere.spi.keygen.ShardingKeyGenerator
内容写上上面自定义的MyShardingKeyGenerator的全类名

同时在pom文件里资源配置里，各个环境都需加上

    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <!-- 资源根目录排除各环境的配置，使用单独的资源目录来指定 -->
                <includes>
                    <include>*/*</include>
                    <include>META-INF/dubbo/com.alibaba.dubbo.rpc.Filter</include>
                    <include>META-INF/app.properties</include>
                    <include>META-INF/services/*</include>
                    <include>static/**</include>
                </includes>
                <!-- 是否替换资源中的属性 -->
                <filtering>true</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <filtering>true</filtering>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
   </build>

shardingsphere踩坑实记

环境概况：
组件 版本
springboot 2.1.1.RELEASE
mybatis-plus-boot-starter 3.0.7.1
sharding-jdbc-spring-boot-starter 4.0.0-RC1
踩坑记录：
报错datasource不能完成注册（The bean ‘dataSource’, defined in class path resource [io/shardingjdbc/spring/boot/SpringBootConfiguration.class], could not be registered.）
解决方案：根据提示加入配置spring.main.allow-bean-definition-overriding=true

实际执行的sql与逻辑sql相同，没有起到分表作用
解决方案：将sharding-jdbc-spring-boot-starter的版本号改为4.0.0-RC1就正常了（RC2和RC3均异常，很无奈，不知道是不是我这边环境有问题）

sql中含有now()函数调用，程序报错
解决方案：service生成时间戳传给dao，sql中直接参数替换，剔除now函数(看来是组件还不支持这个函数解析)

报sql表达式错误，表中含有字段“desc”,因为desc同样为mysql关键字，导致insert时，sql解析出问题，影响了最终参数设置，程序报错。（update/select时都不会影响，唯有insert时出错）
解决方案：将参数改为description，避开mysql关键字

报错缺少antlr4-runtime
解决方案：加入依赖

        <dependency>
            <groupId>org.antlr</groupId>
            <artifactId>antlr4-runtime</artifactId>
            <version>4.7.1</version>
        </dependency>

报错没有收到mysql server回应，感觉就是没连上mysql
解决方案：忘了…（我记得我把maven依赖整体了一下，无用的依赖剔除掉，貌似就可以了）

写了几个demo，如有需要可以自行获取：https://github.com/naget/sharding

原文链接：https://blog.csdn.net/qq_33240946/article/details/103506983