/**
 * @Author 程序猿阿星
 * @Description 分表策略接口
 * @Date 2021/5/9
 */
public interface ITableShardStrategy {


    /**
     * @author: 程序猿阿星
     * @description: 生成分表名
     * @param tableNamePrefix 表前綴名
     * @param value 值
     * @date: 2021/5/9
     * @return: java.lang.String
     */
    String generateTableName(String tableNamePrefix,Object value);

    /**
     * 驗(yàn)證tableNamePrefix
     */
    default void verificationTableNamePrefix(String tableNamePrefix){
        if (StrUtil.isBlank(tableNamePrefix)) {
            throw new RuntimeException("tableNamePrefix is null");
        }
    }
}

/**
 * @Author 程序猿阿星
 * @Description 分表策略id
 * @Date 2021/5/9
 */
@Component
public class TableShardStrategyId implements ITableShardStrategy {
    @Override
    public String generateTableName(String tableNamePrefix, Object value) {
        verificationTableNamePrefix(tableNamePrefix);
        if (value == null || StrUtil.isBlank(value.toString())) {
            throw new RuntimeException("value is null");
        }
        long id = Long.parseLong(value.toString());
        //此處可以緩存優(yōu)化
        return tableNamePrefix + "_" + (id % 2);
    }
}

/**
 * @Author 程序猿阿星
 * @Description 分表注解
 * @Date 2021/5/9
 */
@Target(value = {ElementType.TYPE,ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface TableShard {

    // 表前綴名
    String tableNamePrefix();

    //值
    String value() default "";

    //是否是字段名，如果是需要解析請(qǐng)求參數(shù)改字段名的值（默認(rèn)否）
    boolean fieldFlag() default false;

    // 對(duì)應(yīng)的分表策略類
    Class<? extends ITableShardStrategy> shardStrategy();


}

/**
 * @Author 程序員阿星
 * @Description 分表攔截器
 * @Date 2021/5/9
 */
@Intercepts({
        @Signature(
                type = StatementHandler.class,
                method = "prepare",
                args = {Connection.class, Integer.class}
        )
})
public class TableShardInterceptor implements Interceptor {

    private static final ReflectorFactory defaultReflectorFactory = new DefaultReflectorFactory();

    @Override
    public Object intercept(Invocation invocation) throws Throwable {

        // MetaObject是mybatis里面提供的一個(gè)工具類，類似反射的效果
        MetaObject metaObject = getMetaObject(invocation);
        BoundSql boundSql = (BoundSql) metaObject.getValue("delegate.boundSql");
        MappedStatement mappedStatement = (MappedStatement)
                metaObject.getValue("delegate.mappedStatement");

        //獲取Mapper執(zhí)行方法
        Method method = invocation.getMethod();

        //獲取分表注解
        TableShard tableShard = getTableShard(method,mappedStatement);

        // 如果method與class都沒有TableShard注解或執(zhí)行方法不存在，執(zhí)行下一個(gè)插件邏輯
        if (tableShard == null) {
            return invocation.proceed();
        }

        //獲取值
        String value = tableShard.value();
        //value是否字段名，如果是，需要解析請(qǐng)求參數(shù)字段名的值
        boolean fieldFlag = tableShard.fieldFlag();

        if (fieldFlag) {
            //獲取請(qǐng)求參數(shù)
            Object parameterObject = boundSql.getParameterObject();

            if (parameterObject instanceof MapperMethod.ParamMap) { //ParamMap類型邏輯處理

                MapperMethod.ParamMap parameterMap = (MapperMethod.ParamMap) parameterObject;
                //根據(jù)字段名獲取參數(shù)值
                Object valueObject = parameterMap.get(value);
                if (valueObject == null) {
                    throw new RuntimeException(String.format("入?yún)⒆侄?s無匹配", value));
                }
                //替換sql
                replaceSql(tableShard, valueObject, metaObject, boundSql);

            } else { //單參數(shù)邏輯

                //如果是基礎(chǔ)類型拋出異常
                if (isBaseType(parameterObject)) {
                    throw new RuntimeException("單參數(shù)非法，請(qǐng)使用@Param注解");
                }

                if (parameterObject instanceof Map){
                    Map<String,Object>  parameterMap =  (Map<String,Object>)parameterObject;
                    Object valueObject = parameterMap.get(value);
                    //替換sql
                    replaceSql(tableShard, valueObject, metaObject, boundSql);
                } else {
                    //非基礎(chǔ)類型對(duì)象
                    Class<?> parameterObjectClass = parameterObject.getClass();
                    Field declaredField = parameterObjectClass.getDeclaredField(value);
                    declaredField.setAccessible(true);
                    Object valueObject = declaredField.get(parameterObject);
                    //替換sql
                    replaceSql(tableShard, valueObject, metaObject, boundSql);
                }
            }

        } else {//無需處理parameterField
            //替換sql
            replaceSql(tableShard, value, metaObject, boundSql);
        }
        //執(zhí)行下一個(gè)插件邏輯
        return invocation.proceed();
    }


    @Override
    public Object plugin(Object target) {
        // 當(dāng)目標(biāo)類是StatementHandler類型時(shí)，才包裝目標(biāo)類，否者直接返回目標(biāo)本身, 減少目標(biāo)被代理的次數(shù)
        if (target instanceof StatementHandler) {
            return Plugin.wrap(target, this);
        } else {
            return target;
        }
    }


    /**
     * @param object
     * @methodName: isBaseType
     * @author: 程序員阿星
     * @description: 基本數(shù)據(jù)類型驗(yàn)證，true是，false否
     * @date: 2021/5/9
     * @return: boolean
     */
    private boolean isBaseType(Object object) {
        if (object.getClass().isPrimitive()
                || object instanceof String
                || object instanceof Integer
                || object instanceof Double
                || object instanceof Float
                || object instanceof Long
                || object instanceof Boolean
                || object instanceof Byte
                || object instanceof Short) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * @param tableShard 分表注解
     * @param value      值
     * @param metaObject mybatis反射對(duì)象
     * @param boundSql   sql信息對(duì)象
     * @author: 程序猿阿星
     * @description: 替換sql
     * @date: 2021/5/9
     * @return: void
     */
    private void replaceSql(TableShard tableShard, Object value, MetaObject metaObject, BoundSql boundSql) {
        String tableNamePrefix = tableShard.tableNamePrefix();
        //獲取策略class
        Class<? extends ITableShardStrategy> strategyClazz = tableShard.shardStrategy();
        //從spring ioc容器獲取策略類

        ITableShardStrategy tableShardStrategy = SpringUtil.getBean(strategyClazz);
        //生成分表名
        String shardTableName = tableShardStrategy.generateTableName(tableNamePrefix, value);
        // 獲取sql
        String sql = boundSql.getSql();
        // 完成表名替換
        metaObject.setValue("delegate.boundSql.sql", sql.replaceAll(tableNamePrefix, shardTableName));
    }

    /**
     * @param invocation
     * @author: 程序猿阿星
     * @description: 獲取MetaObject對(duì)象-mybatis里面提供的一個(gè)工具類，類似反射的效果
     * @date: 2021/5/9
     * @return: org.apache.ibatis.reflection.MetaObject
     */
    private MetaObject getMetaObject(Invocation invocation) {
        StatementHandler statementHandler = (StatementHandler) invocation.getTarget();
        // MetaObject是mybatis里面提供的一個(gè)工具類，類似反射的效果
        MetaObject metaObject = MetaObject.forObject(statementHandler,
                SystemMetaObject.DEFAULT_OBJECT_FACTORY,
                SystemMetaObject.DEFAULT_OBJECT_WRAPPER_FACTORY,
                defaultReflectorFactory
        );

        return metaObject;
    }

    /**
     * @author: 程序猿阿星
     * @description: 獲取分表注解
     * @param method
     * @param mappedStatement
     * @date: 2021/5/9
     * @return: com.xing.shard.interceptor.TableShard
     */
    private TableShard getTableShard(Method method, MappedStatement mappedStatement) throws ClassNotFoundException {
        String id = mappedStatement.getId();
        //獲取Class
        final String className = id.substring(0, id.lastIndexOf("."));
        //分表注解
        TableShard tableShard = null;
        //獲取Mapper執(zhí)行方法的TableShard注解
        tableShard = method.getAnnotation(TableShard.class);
        //如果方法沒有設(shè)置注解，從Mapper接口上面獲取TableShard注解
        if (tableShard == null) {
            // 獲取TableShard注解
            tableShard = Class.forName(className).getAnnotation(TableShard.class);
        }
        return tableShard;
    }

}

/**
 * @Author wx
 * @Description 分表策略日期
 * @Date 2021/5/9
 */
@Component
public class TableShardStrategyDate implements ITableShardStrategy {

    private static final String DATE_PATTERN = "yyyyMM";

    @Override
    public String generateTableName(String tableNamePrefix, Object value) {
        verificationTableNamePrefix(tableNamePrefix);
        if (value == null || StrUtil.isBlank(value.toString())) {
            return tableNamePrefix + "_" +DateUtil.format(new Date(), DATE_PATTERN);
        } else {
            return tableNamePrefix + "_" +DateUtil.format(new Date(), value.toString());
        }
    }
}



**
 * @Author 程序猿阿星
 * @Description 分表策略id
 * @Date 2021/5/9
 */
@Component
public class TableShardStrategyId implements ITableShardStrategy {
    @Override
    public String generateTableName(String tableNamePrefix, Object value) {
        verificationTableNamePrefix(tableNamePrefix);
        if (value == null || StrUtil.isBlank(value.toString())) {
            throw new RuntimeException("value is null");
        }
        long id = Long.parseLong(value.toString());
        //可以加入本地緩存優(yōu)化
        return tableNamePrefix + "_" + (id % 2);
    }
}

/**
 * @Author 程序猿阿星
 * @Description
 * @Date 2021/5/8
 */
@TableShard(tableNamePrefix = "tb_log_date",shardStrategy = TableShardStrategyDate.class)
public interface LogDateMapper {

    /**
     * 查詢列表-根據(jù)日期分表
     */
    List<LogDate> queryList();

    /**
     * 單插入-根據(jù)日期分表
     */
    void  save(LogDate logDate);

}


-------------------------------------------------------------------------------------------------


/**
 * @Author 程序猿阿星
 * @Description
 * @Date 2021/5/8
 */
@TableShard(tableNamePrefix = "tb_log_id",value = "id",fieldFlag = true,shardStrategy = TableShardStrategyId.class)
public interface LogIdMapper {

    /**
     * 根據(jù)id查詢-根據(jù)id分片
     */
    LogId queryOne(@Param("id") long id);

    /**
     * 單插入-根據(jù)id分片
     */
    void save(LogId logId);
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xing.shard.mapper.LogDateMapper">
    
    //對(duì)應(yīng)LogDateMapper#queryList函數(shù)
    <select id="queryList" resultType="com.xing.shard.entity.LogDate">
        select
        id as id,
        comment as comment,
        create_date as createDate
        from
        tb_log_date
    </select>
    
    //對(duì)應(yīng)LogDateMapper#save函數(shù)
    <insert id="save" >
        insert into tb_log_date(id, comment,create_date)
        values (#{id}, #{comment},#{createDate})
    </insert>
</mapper>

-------------------------------------------------------------------------------------------------

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xing.shard.mapper.LogIdMapper">
    
    //對(duì)應(yīng)LogIdMapper#queryOne函數(shù)
    <select id="queryOne" resultType="com.xing.shard.entity.LogId">
        select
        id as id,
        comment as comment,
        create_date as createDate
        from
        tb_log_id
        where
        id = #{id}
    </select>
    
    //對(duì)應(yīng)save函數(shù)
    <insert id="save" >
        insert into tb_log_id(id, comment,create_date)
        values (#{id}, #{comment},#{createDate})
    </insert>

</mapper>

    @Test
    void test() {
        LogDate logDate = new LogDate();
        logDate.setId(snowflake.nextId());
        logDate.setComment("測(cè)試內(nèi)容");
        logDate.setCreateDate(new Date());
        //插入
        logDateMapper.save(logDate);
        //查詢
        List<LogDate> logDates = logDateMapper.queryList();
        System.out.println(JSONUtil.toJsonPrettyStr(logDates));
    }

    @Test
    void test() {
        LogId logId = new LogId();
        long id = snowflake.nextId();
        logId.setId(id);
        logId.setComment("測(cè)試");
        logId.setCreateDate(new Date());
        //插入
        logIdMapper.save(logId);
        //查詢
        LogId logIdObject = logIdMapper.queryOne(id);
        System.out.println(JSONUtil.toJsonPrettyStr(logIdObject));
    }