背景
近期在项目中需要使用多数据源，其中有一些表的数据量比较大，需要对其进行分库分表；而其他数据表数据量比较正常，单表就可以。
项目中可能使用其他组的数据源数据，因此需要多数据源支持。
经过调研多数据源配置比较方便。在该项目中分库分表的策略比较简单，仅根据一个字段分就可以，因此分库分表方案选用比较流行方便易用的 sharding-jdbc
需要实现的目标是 根据学生姓名字段 student_name 进行分表，但是不需要分库。数据表是student_hist0 - student_hist9
引入 sharding-jdbc maven 依赖
<dependency>
<groupId>org.apache.shardingsphere</groupId>
<artifactId>sharding-jdbc-core</artifactId>
<version>4.1.1</version>
</dependency>
数据源配置文件
spring:
application:
name: student-service-provider
jackson:
date-format: yyyy-MM-dd HH:mm:ss
time-zone: GMT+8
defaultPropertyInclusion: non_null
deserialization:
FAIL_ON_UNKNOWN_PROPERTIES: false
#对返回的时间进行格式化
datasource:
hikari:
student:
url: jdbc:mysql://127.0.0.1:3306/student_service?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&useTimezone=true&serverTimezone=GMT%2
username: root
password: root123
log1:
url: jdbc:mysql://127.0.0.1:3306/log1?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false
username: root
password: root123
log2:
url: jdbc:mysql://127.0.0.1:3306/log2?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false
username: root
password: root123
配置多数据源代码
DataSourceProperties 数据源
import com.zaxxer.hikari.HikariDataSource;
import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
@Data
@Configuration
@ConfigurationProperties(prefix = "spring.datasource.hikari")
public class DataSourceProperties {
private HikariDataSource student;
private HikariDataSource log1;
private HikariDataSource log2;
}
DynamicDataSource 动态数据源
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
public class DynamicDataSource extends AbstractRoutingDataSource {
/*
当前据源名称
*/
private static final ThreadLocal<String> dataSourceContextHolder = new ThreadLocal<>();
/*
设置数据源名称
*/
public static void setDataSourceName(String dataSourceName) {
dataSourceContextHolder.set(dataSourceName);
}
/*
获取据源名称
*/
public static String getDataSourceName() {
return dataSourceContextHolder.get();
}
/*
清除当数据源名称
*/
public static void clearDataSource() {
dataSourceContextHolder.remove();
}
@Override
protected Object determineCurrentLookupKey() {
return getDataSourceName();
}
}
MultiDataSource 多数据源标记
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface MultiDataSource {
String value() default DataSourceConfig.DEFAULT_DATASOURCE_NAME;
}
重点来了，因为是根据表的某一个字段进行分表，该字段是一个字符串类型，因此需要想根据字符串的一致性hash码算出在哪张表上。在sharding-jdbc需要实现 PreciseShardingAlgorithm 类
例如：想要在student.student_hist 表中根据学生姓名进行分表，逻辑表是student_hist，真实表是 student_hist0 - student_hist9
DataSourceConfig.SHARD_MMS_DATASOURCE_TABLE_COUNT=10
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingAlgorithm;
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingValue;
import java.util.Collection;
public class PreciseNodeIdShardingAlgorithm implements PreciseShardingAlgorithm<String> {
@Override
public String doSharding(Collection<String> collection, PreciseShardingValue<String> preciseShardingValue) {
for (String tbnm : collection) {
if (tbnm.endsWith("hist" + (getHash(preciseShardingValue.getValue()) % DataSourceConfig.SHARD_MMS_DATASOURCE_TABLE_COUNT))) {
return tbnm;
}
}
throw new UnsupportedOperationException();
}
private static int getHash(String str) {
final int p = 16777619;
int hash = (int) 2166136261L;
for (int i = 0; i < str.length(); i++)
hash = (hash ^ str.charAt(i)) * p;
hash += hash << 13;
hash ^= hash >> 7;
hash += hash << 3;
hash ^= hash >> 17;
hash += hash << 5;
// 如果算出来的值为负数则取其绝对值
if (hash < 0)
hash = Math.abs(hash);
return hash;
}
}
多数据源装配 DataSourceConfig 。需要指定默认数据源，当不需要使用 分表的表时就使用默认的数据源，否则指定需要分表的数据源。
在配置分表策略时如果不需要分库，可以不进行设置 tableRuleConfiguration.setDatabaseShardingStrategyConfig();
import org.apache.shardingsphere.api.config.sharding.ShardingRuleConfiguration;
import org.apache.shardingsphere.api.config.sharding.TableRuleConfiguration;
import org.apache.shardingsphere.api.config.sharding.strategy.StandardShardingStrategyConfiguration;
import org.apache.shardingsphere.shardingjdbc.api.ShardingDataSourceFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import javax.sql.DataSource;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
@Configuration
public class DataSourceConfig {
public static final String DEFAULT_DATASOURCE_NAME = "defaultDataSource";
public static final String MMS_DATASOURCE_NAME = "mmsDatasource";
public static final String SHARD_MMS_DATASOURCE_NAME = "shardMmsDatasource";
public static int SHARD_MMS_DATASOURCE_TABLE_COUNT = 10;
@Autowired
private DataSourceProperties properties;
@Primary
@Bean(name = "dynamicDataSource")
public DataSource dynamicDataSource() {
DynamicDataSource dynamicDataSource = new DynamicDataSource();
// 默认数据源
dynamicDataSource.setDefaultTargetDataSource(properties.getMms());
// 配置多数据源
Map<Object, Object> dsMap = new HashMap();
dsMap.put(DEFAULT_DATASOURCE_NAME, properties.getStudent());
dsMap.put(MMS_DATASOURCE_NAME, properties.getStudent());
dsMap.put(SHARD_MMS_DATASOURCE_NAME, buildShardDatasources());
dynamicDataSource.setTargetDataSources(dsMap);
return dynamicDataSource;
}
public DataSource buildShardDatasources() {
// 配置多数据源
Map<String, DataSource> dsMap = new HashMap();
dsMap.put("shardMms", properties.getMms());
TableRuleConfiguration stuHisTableRuleConfig = new TableRuleConfiguration("student_hist", "shardMms.student_hist${0.." + (SHARD_MMS_DATASOURCE_TABLE_COUNT - 1) + "}");
// tableRuleConfiguration.setDatabaseShardingStrategyConfig();
stuHisTableRuleConfig.setTableShardingStrategyConfig(new StandardShardingStrategyConfiguration("student_name", new PreciseNodeIdShardingAlgorithm()));
ShardingRuleConfiguration shardingRuleConfig = new ShardingRuleConfiguration();
shardingRuleConfig.getTableRuleConfigs().add(stuHisTableRuleConfig);
try {
Properties properties = new Properties();
properties.setProperty("sql.show", "true");
return ShardingDataSourceFactory.createDataSource(dsMap, shardingRuleConfig, properties);
} catch (SQLException throwables) {
throwables.printStackTrace();
throw new IllegalArgumentException();
}
}
@Bean
public PlatformTransactionManager transactionManager() {
return new DataSourceTransactionManager(dynamicDataSource());
}
}
多数据源切换 DataSourceAspect ,需要使用多数据源切换时，需要在service方法上使用标注方法 MultiDataSource 并指定数据源。
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.annotation.Order;
import java.lang.reflect.Method;
@Aspect
@Configuration
@Slf4j
@Order(1)
public class DataSourceAspect {
//切入点，service 中所有注解方法
@Pointcut("execution(* com.huitong..service..*.*(..)) && @annotation(com.huitong.app.config.datasource.MultiDataSource)")
public void dataSourceAspect() {
}
@Around("dataSourceAspect()")
public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
MethodSignature signature = (MethodSignature) joinPoint.getSignature();
Method method = signature.getMethod();
MultiDataSource ds = method.getAnnotation(MultiDataSource.class);
if (ds != null) {
DynamicDataSource.setDataSourceName(ds.value());
}
try {
return joinPoint.proceed();
} finally {
DynamicDataSource.clearDataSource();
}
}
}