订单迁移TIDB 实现读写分离

目标

• 读写分离

准备工作

• 数据源准备
• 动态数据源切换
  • 参考 AbstractRoutingDataSource

配置数据源

//DruidDataSourceBuilder自行引入starter包
@Configuration
@Component
public class DynamicDataSourceConfig {

    @Bean
    @ConfigurationProperties("spring.datasource.master")
    public DataSource  master(){
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties("spring.datasource.slave")
    public DataSource  slave(){
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @Primary
    public DynamicDataSource dataSource(DataSource master, DataSource slave) {
        Map<Object, Object> allDataSources = new HashMap<>();
        targetDataSources.put("master",master);
        targetDataSources.put("slave", slave);
        return new DynamicDataSource(master, allDataSources);
    }
}

动态数据源切换

public class DynamicDataSource  extends AbstractRoutingDataSource {

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    public DynamicDataSource(DataSource defaultDataSource, Map<Object, Object> allDataSources) {
        super.setDefaultTargetDataSource(defaultDataSource);
        super.setTargetDataSources(allDataSources);
        super.afterPropertiesSet();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return getDataSource();
    }

    public static void setDataSource(String dataSource) {
        contextHolder.set(dataSource);
    }

    public static String getDataSource() {
        return contextHolder.get();
    }

    public static void clearDataSource() {
        contextHolder.remove();
    }
}

配置切换注解

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface DataSource {
    String name() default "";
}

AOP切换

@Aspect
@Component
public class DataSourceAspect {

    @Pointcut("@annotation(xx.xx.xx.DataSource)")
    public void dataSourcePointCut() {

    }

    @Around("dataSourcePointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();

        DataSource dataSource = method.getAnnotation(DataSource.class);
        if(dataSource == null){
            // 如果方法上没有加注解. 默认导向到master去
            DynamicDataSource.setDataSource("master");
        }else {
            // 如果方法上加了注解,导向到标记的数据源
            DynamicDataSource.setDataSource(dataSource.name());
        }
        try {
            return point.proceed();
        } finally {
            // 执行结束后清除thread local中的记录
            DynamicDataSource.clearDataSource();
        }
    }
}

使用方式

/**
 * 查询master库User,下面的master可以考虑定义成常量
 */
@DataSource(name="master")
public List<TestUser> getMasterUser(){
    QueryWrapper<TestUser> queryWrapper = new QueryWrapper<>();
    return testUserMapper.selectAll(queryWrapper.isNotNull("name"));
}