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sharding sphere 4.0.0-RC1版本 按年分表(后续优化)

1. sharding sphere 4.0.0-RC1版本 按年分表(后续优化)

1.1. 概述

关于上一篇中LogShardingAlgorithmtables,我原先是在第一次调用的时候初始化,这样做虽然能实现功能,但每次调用都会走这个if判断,虽然性能损耗不大,但我觉得这不是业务应该走的逻辑顺序,我的理想是在LogShardingAlgorithm被实例化后去自动初始化tables

现在面对的问题是LogShardingAlgorithm的实例化是在Spring初始化中间执行的,且它本身的创建不是通过Spring的@Component等注解生成,而是通过反射实例化。若在实例化刚开始,也就是构造方法执行的时候执行初始化,那时候applicationContext还没有初始化完毕,拿不到环境参数,连Datasource也还没开始初始化

1.2. 解决方法

经过改造后,代码如下,单独拎出一个初始化方法,在类对象实例化后调用

/**
 * @author: laoliangliang
 * @description: 日志分片
 * @create: 2020/1/2 10:19
 **/
@Slf4j
public class LogShardingAlgorithm implements PreciseShardingAlgorithm, RangeShardingAlgorithm<Integer> {
/**
 * 缓存存在的表
 */
private List&lt;String&gt; tables;

private final String systemLogHead = "system_log_";

public void init(){
    tables = DBUtil.getAllSystemLogTable();
}

@Override
public String doSharding(Collection availableTargetNames, PreciseShardingValue shardingValue) {
    String target = shardingValue.getValue().toString();
    String year = target.substring(target.lastIndexOf("_") + 1, target.lastIndexOf("_") + 5);
    if (!tables.contains(systemLogHead + year)) {
        DBUtil.createLogTable(year);
        tables.add(year);
    }
    return shardingValue.getLogicTableName() + "_" + year;
}

@Override
public Collection&lt;String&gt; doSharding(Collection&lt;String&gt; availableTargetNames, RangeShardingValue&lt;Integer&gt; shardingValue) {
    Collection&lt;String&gt; availables = new ArrayList&lt;&gt;();
    Range valueRange = shardingValue.getValueRange();
    for (String target : tables) {
        Integer shardValue = Integer.parseInt(target.substring(target.lastIndexOf("_") + 1, target.lastIndexOf("_") + 5));
        if (valueRange.hasLowerBound()) {
            String lowerStr = valueRange.lowerEndpoint().toString();
            Integer start = Integer.parseInt(lowerStr.substring(0, 4));
            if (start - shardValue &gt; 0) {
                continue;
            }
        }
        if (valueRange.hasUpperBound()) {
            String upperStr = valueRange.upperEndpoint().toString();
            Integer end = Integer.parseInt(upperStr.substring(0, 4));
            if (end - shardValue &lt; 0) {
                continue;
            }
        }
        availables.add(target);
    }
    return availables;
}

}

其中init方法通过另一个类实例化完成后调用,难点在于如何拿到该实例化的LogShardingAlgorithm

import cn.hutool.core.util.ReflectUtil;
import com.google.common.base.Optional;
import com.onegene.platform.system.log.LogShardingAlgorithm;
import org.apache.shardingsphere.core.rule.ShardingRule;
import org.apache.shardingsphere.core.rule.TableRule;
import org.apache.shardingsphere.core.strategy.route.ShardingStrategy;
import org.apache.shardingsphere.shardingjdbc.jdbc.core.ShardingContext;
import org.apache.shardingsphere.shardingjdbc.jdbc.core.datasource.ShardingDataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct; import javax.sql.DataSource; /**

  • @author: laoliangliang

  • @description:

  • @create: 2020/1/18 8:29 **/ @Component public class StartupConfig { @Autowired private DataSource dataSource;

    @PostConstruct public void init() { this.loadLogInit(); }

    private void loadLogInit() { if (dataSource instanceof ShardingDataSource) { ShardingDataSource sds = (ShardingDataSource) dataSource; ShardingContext shardingContext = sds.getShardingContext(); ShardingRule shardingRule = shardingContext.getShardingRule(); Optional<TableRule> systemLog = shardingRule.findTableRule("system_log"); TableRule tableRule = systemLog.orNull(); if (tableRule != null) { ShardingStrategy tableShardingStrategy = tableRule.getTableShardingStrategy(); LogShardingAlgorithm preciseShardingAlgorithm = (LogShardingAlgorithm) ReflectUtil.getFieldValue(tableShardingStrategy, "preciseShardingAlgorithm"); LogShardingAlgorithm rangeShardingAlgorithm = (LogShardingAlgorithm) ReflectUtil.getFieldValue(tableShardingStrategy, "rangeShardingAlgorithm"); preciseShardingAlgorithm.init(); rangeShardingAlgorithm.init(); } } } }

1.3. 总结

通过查看源码可以知道,它最后把LogShardingAlgorithm实例化的对象放入了ShardingDataSource,那我们就要从里面把它取出来,若它正常没提供get方法,那我们就用反射硬把它取出来

通过上述代码可以看出,范围分片和精确分片需要实例化两个类,我想是否可以合到一个类,网上也找了一下,发现有的版本使用ComplexKeysShardingAlgorithm算法是可以同时实现范围和精确分片查询的,但经过我实际测试,现在的4.0.0版本不行,原因在于以下代码,此为复杂分片源码

public final class ComplexShardingStrategy implements ShardingStrategy {
@Getter
private final Collection&lt;String&gt; shardingColumns;

private final ComplexKeysShardingAlgorithm shardingAlgorithm;

public ComplexShardingStrategy(final ComplexShardingStrategyConfiguration complexShardingStrategyConfig) {
    Preconditions.checkNotNull(complexShardingStrategyConfig.getShardingColumns(), "Sharding columns cannot be null.");
    Preconditions.checkNotNull(complexShardingStrategyConfig.getShardingAlgorithm(), "Sharding algorithm cannot be null.");
    shardingColumns = new TreeSet&lt;&gt;(String.CASE_INSENSITIVE_ORDER);
    shardingColumns.addAll(Splitter.on(",").trimResults().splitToList(complexShardingStrategyConfig.getShardingColumns()));
    shardingAlgorithm = complexShardingStrategyConfig.getShardingAlgorithm();
}

@SuppressWarnings("unchecked")
@Override
public Collection&lt;String&gt; doSharding(final Collection&lt;String&gt; availableTargetNames, final Collection&lt;RouteValue&gt; shardingValues) {
    Map&lt;String, Collection&lt;Comparable&lt;?&gt;&gt;&gt; columnShardingValues = new HashMap&lt;&gt;(shardingValues.size(), 1);
    String logicTableName = "";
    for (RouteValue each : shardingValues) {

        // 重点这里他把each的值强行转化成了ListRouteValue而范围查询对应的为BetweenRouteValue,所以在源码级别就被卡死了,除非重写策略,否则这个已经不能像以前那样用了
        columnShardingValues.put(each.getColumnName(), ((ListRouteValue) each).getValues());
        logicTableName = each.getTableName();
    }
    Collection&lt;String&gt; shardingResult = shardingAlgorithm.doSharding(availableTargetNames, new ComplexKeysShardingValue(logicTableName, columnShardingValues));
    Collection&lt;String&gt; result = new TreeSet&lt;&gt;(String.CASE_INSENSITIVE_ORDER);
    result.addAll(shardingResult);
    return result;
}

}

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本文由【老梁Java】发布于开源中国,原文链接:https://my.oschina.net/u/3703487/blog/3159709

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