1. sharding简介
ShardingSphere是一套开源的分布式数据库中间件解决方案组成的生态圈，目前已在阿帕奇孵化成功,它由Sharding-JDBC、Sharding-Proxy和Sharding-Sidecar（计划中）这3款相互独立的产品组成，这里主要介绍shardingjdbc,文档地址 https://shardingsphere.apache.org/document/current/cn/overview/
2. 使用
1.引入maven包
这里不适用start包,而直接使用原包,这里还需要排除sharding的mysql连接器,使用自己的连接器
<!-- https://mvnrepository.com/artifact/io.shardingsphere/sharding-jdbc-core -->
<dependency>
<groupId>io.shardingsphere</groupId>
<artifactId>sharding-jdbc-core</artifactId>
<version>3.1.0</version>
<exclusions>
<exclusion>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</exclusion>
</exclusions>
</dependency>
2.配置
sharding和动态数据源整合一起,因为sharding会全局解析所有sql,在某些情况下mybatis能解析的sql语句sharding是没办法解析的,会导致以前的业务sql出现问题,所以我们通过动态数据源和注解的形式标注哪些sql需要使用sharding的数据源,灵活配置
DynamicDataSource
/**
* 动态数据源
* Created by tyf on 2019/9/25 0025
*/
public class DynamicDataSource extends AbstractRoutingDataSource {
//用来保存数据源与获取数据源
private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();
public DynamicDataSource(DataSource defaultTargetDataSource, Map<String, DataSource> targetDataSources) {
super.setDefaultTargetDataSource(defaultTargetDataSource);
super.setTargetDataSources(new HashMap<>(targetDataSources));
super.afterPropertiesSet();
}
public static void setDataSource(String dataSource) {
contextHolder.set(dataSource);
}
public static String getDataSource() {
return contextHolder.get();
}
public static void clearDataSource() {
contextHolder.remove();
}
@Override
protected Object determineCurrentLookupKey() {
return getDataSource();
}
}
ShardingDataSourceAspect 动态数据源aop切面,使用springboot的方式
/**
* 动态数据源aop切面
* Created by tyf on 2019/9/25 0025
*/
@Aspect
public class ShardingDataSourceAspect {
@Around(ExecutionConstant.CONTROLLER + "||" + ExecutionConstant.SERVICE)
public Object around(ProceedingJoinPoint point) throws Throwable {
// 获取方法名
String methodName = point.getSignature().getName();
// 反射获取目标类
Class<?> targetClass = point.getTarget().getClass();
// 拿到方法对应的参数类型
Class<?>[] parameterTypes = ((MethodSignature) point.getSignature()).getParameterTypes();
// 根据类、方法、参数类型（重载）获取到方法的具体信息
Method method = targetClass.getMethod(methodName, parameterTypes);
final ShardingDataSource methodAnnotation = AnnotationUtils.findAnnotation(method, ShardingDataSource.class);
final ShardingDataSource classAnnotation = AnnotationUtils.findAnnotation(targetClass, ShardingDataSource.class);
//当类和方法上都没注解的时候,跳过
if (methodAnnotation == null && classAnnotation == null) {
return point.proceed();
}
DynamicDataSource.setDataSource(DataSourceNames.SHARDING);
try {
return point.proceed();
} finally {
DynamicDataSource.clearDataSource();
}
}
}
ShardingDataSource,注解
/**
* Created by tyf on 2019/9/25 0025
*/
@Target({ ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ShardingDataSource {
}
DataSourceNames常量
/**
* Created by tyf on 2019/9/25 0025
*/
public interface DataSourceNames {
String DEFAULT = "default";
String SHARDING = "sharding";
}
ShardingConfiguration,sharding配置类,将配置抽象在基础包中,只有当业务项目有ShardingRuleConfiguration类之后才会加载sharding配置类
@Configuration
@DependsOn("springTools")
@ConditionalOnBean({ShardingRuleConfiguration.class})
public class ShardingConfiguration {
/**
* 代理切面类
*
* @return
*/
@Bean
public ShardingDataSourceAspect shardingDataSourceAspect() {
return new ShardingDataSourceAspect();
}
/**
* 多数据源,默认为springboot数据源,使用{@link ShardingDataSource} 标记为sharding数据源
*
* @param dataSourceProperties
* @param shardingRuleConfiguration
* @return
* @throws SQLException
*/
@Bean
@Primary
public DynamicDataSource dataSource(DataSourceProperties dataSourceProperties, ShardingRuleConfiguration shardingRuleConfiguration) throws SQLException {
//初始化springboot数据源
final DataSource dataSource = dataSourceProperties.initializeDataSourceBuilder().build();
//设置动态数据源
Map<String, DataSource> targetDataSources = new HashMap<>();
targetDataSources.put(DataSourceNames.DEFAULT, dataSource);
targetDataSources.put(DataSourceNames.SHARDING, getShardingDataSource(dataSource, shardingRuleConfiguration));
return new DynamicDataSource(dataSource, targetDataSources);
}
private DataSource getShardingDataSource(DataSource dataSource, ShardingRuleConfiguration shardingRuleConfiguration) throws SQLException {
final Properties properties = new Properties();
// 获取数据源对象
final DataSource shardingDatasource = ShardingDataSourceFactory.createDataSource(ImmutableMap.of("ds0", dataSource),
shardingRuleConfiguration, new ConcurrentHashMap(), properties);
return shardingDatasource;
}
}
在业务项目中,你只需要配置ShardingRuleConfiguration即可开箱使用sharding了,例如
/**
* sharding分片规则
*
* @return
*/
@Bean
@Primary
public ShardingRuleConfiguration shardingRuleConfiguration() {
final ShardingRuleConfiguration shardingRuleConfiguration = new ShardingRuleConfiguration();
TableRuleConfiguration sappPaperRankingTableRuleConfig = new TableRuleConfiguration();
sappPaperRankingTableRuleConfig.setLogicTable("sapp_paper_ranking");
//选需要分片的对应的库和表
sappPaperRankingTableRuleConfig.setActualDataNodes("ds0.sapp_paper_ranking_0${1..9},ds0.sapp_paper_ranking_${10..31}");
// 配置分库 + 分表策略
sappPaperRankingTableRuleConfig.setDatabaseShardingStrategyConfig(new NoneShardingStrategyConfiguration());
sappPaperRankingTableRuleConfig.setTableShardingStrategyConfig(new StandardShardingStrategyConfiguration(
"create_date", new SappPaperRankingPreciseShardingAlgorithm()));
// 配置分片规则
shardingRuleConfiguration.getTableRuleConfigs().add(sappPaperRankingTableRuleConfig);
return shardingRuleConfiguration;
}
/**
* 精确分片算法,=与IN进行分片
*/
public class SappPaperRankingPreciseShardingAlgorithm implements PreciseShardingAlgorithm<Integer> {
@Override
public String doSharding(Collection<String> tableNames/*表名*/, PreciseShardingValue<Integer> shardingValue /*分片键*/) {
final Integer uid = shardingValue.getValue();
/*省略*/
throw new UnsupportedOperationException();
}
}
