nacos适配达梦、瀚高、人大金仓数据库及部分源码探究

一.插件实现

　　1.插件目录结构

　　2.pom依赖

        <dependency>
            <groupId>com.alibaba.nacos</groupId>
            <artifactId>nacos-datasource-plugin</artifactId>
            <version>2.2.4</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>3.1.3.RELEASE</version>
        </dependency>
        <!-- 达梦 -->
        <dependency>
            <groupId>com.dameng</groupId>
            <artifactId>Dm8JdbcDriver18</artifactId>
            <version>8.1.1.49</version>
        </dependency>
        <!-- 瀚高 -->
        <dependency>
            <groupId>com.highgo</groupId>
            <artifactId>HgdbJdbc</artifactId>
            <version>6.2.2</version>
        </dependency>
        <!--人大金仓 -->
        <dependency>
            <groupId>com.kingbase</groupId>
            <artifactId>kingbase8</artifactId>
            <version>8.2.0</version>
        </dependency>

　　3.代码实现

　　3.1.DataSourceConstant

public class DataSourceConstant {
    public static final String MYSQL = "mysql";

    public static final String DERBY = "derby";

    public static final String DM="dm";

    public static final String HIGHGO="highgo";

    public static final String KINGBASE="kingbase";

}

　　3.2.公共方法

　　 3.2.1.AbstractConfigInfoAggrMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.ConfigInfoAggrMapper;

public abstract class AbstractConfigInfoAggrMapperCommon extends AbstractMapper implements ConfigInfoAggrMapper {

    @Override
    public String batchRemoveAggr(int datumSize) {
        final StringBuilder placeholderString = new StringBuilder();
        for (int i = 0; i < datumSize; i++) {
            if (i != 0) {
                placeholderString.append(", ");
            }
            placeholderString.append('?');
        }
        return "DELETE FROM config_info_aggr WHERE data_id = ? AND group_id = ? AND tenant_id = ? AND datum_id IN ("
                + placeholderString + ")";
    }

    @Override
    public String aggrConfigInfoCount(int size, boolean isIn) {
        StringBuilder sql = new StringBuilder(
                "SELECT count(*) FROM config_info_aggr WHERE data_id = ? AND group_id = ? AND tenant_id = ? AND datum_id");
        if (isIn) {
            sql.append(" IN (");
        } else {
            sql.append(" NOT IN (");
        }
        for (int i = 0; i < size; i++) {
            if (i > 0) {
                sql.append(", ");
            }
            sql.append('?');
        }
        sql.append(')');

        return sql.toString();
    }

    public String findConfigInfoAggrIsOrdered() {
        return "SELECT data_id,group_id,tenant_id,datum_id,app_name,content FROM "
                + "config_info_aggr WHERE data_id = ? AND group_id = ? AND tenant_id = ? ORDER BY datum_id";
    }

    public String findConfigInfoAggrByPageFetchRows(int startRow, int pageSize) {
        return "SELECT data_id,group_id,tenant_id,datum_id,app_name,content FROM config_info_aggr WHERE data_id= ? AND "
                + "group_id= ? AND tenant_id= ? ORDER BY datum_id LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String findAllAggrGroupByDistinct() {
        return "SELECT DISTINCT data_id, group_id, tenant_id FROM config_info_aggr";
    }

    public String getTableName() {
        return TableConstant.CONFIG_INFO_AGGR;
    }

}

　　 3.2.2.AbstractConfigInfoBetaMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.ConfigInfoBetaMapper;

public abstract class AbstractConfigInfoBetaMapperCommon extends AbstractMapper implements ConfigInfoBetaMapper {

    public String updateConfigInfo4BetaCas() {
        return "UPDATE config_info_beta SET content = ?,md5 = ?,beta_ips = ?,src_ip = ?,src_user = ?,gmt_modified = ?,app_name = ? "
                + "WHERE data_id = ? AND group_id = ? AND tenant_id = ? AND (md5 = ? or md5 is null or md5 = '')";
    }

    public String findAllConfigInfoBetaForDumpAllFetchRows(int startRow, int pageSize) {
        return " SELECT t.id,data_id,group_id,tenant_id,app_name,content,md5,gmt_modified,beta_ips,encrypted_data_key "
                + " FROM ( SELECT id FROM config_info_beta  ORDER BY id LIMIT " + pageSize + " OFFSET " + startRow
                + " )" + "  g, config_info_beta t WHERE g.id = t.id ";
    }

    public String getTableName() {
        return TableConstant.CONFIG_INFO_BETA;
    }
}

　　 3.2.3.AbstractConfigInfoTagMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.ConfigInfoTagMapper;

public abstract class AbstractConfigInfoTagMapperCommon extends AbstractMapper implements ConfigInfoTagMapper {

    public String updateConfigInfo4TagCas() {
        return "UPDATE config_info_tag SET content = ?, md5 = ?, src_ip = ?,src_user = ?,gmt_modified = ?,app_name = ? "
                + "WHERE data_id = ? AND group_id = ? AND tenant_id = ? AND tag_id = ? AND (md5 = ? OR md5 IS NULL OR md5 = '')";
    }

    public String findAllConfigInfoTagForDumpAllFetchRows(int startRow, int pageSize) {
        return " SELECT t.id,data_id,group_id,tenant_id,tag_id,app_name,content,md5,gmt_modified "
                + " FROM (  SELECT id FROM config_info_tag  ORDER BY id LIMIT " + pageSize + " OFFSET " + startRow
                + " ) " + "g, config_info_tag t  WHERE g.id = t.id  ";
    }

    public String getTableName() {
        return TableConstant.CONFIG_INFO_TAG;
    }

}

　　 3.2.4.AbstractConfigTagsRelationMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.common.utils.StringUtils;
import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.ConfigTagsRelationMapper;

import java.util.Map;

public abstract class AbstractConfigTagsRelationMapperCommon extends AbstractMapper implements ConfigTagsRelationMapper {

    public String findConfigInfo4PageCountRows(final Map<String, String> params, final int tagSize) {
        final String appName = params.get("appName");
        final String dataId = params.get("dataId");
        final String group = params.get("group");
        StringBuilder where = new StringBuilder(" WHERE ");
        final String sqlCount = "SELECT count(*) FROM config_info  a LEFT JOIN config_tags_relation b ON a.id=b.id";
        where.append(" a.tenant_id=? ");
        if (StringUtils.isNotBlank(dataId)) {
            where.append(" AND a.data_id=? ");
        }
        if (StringUtils.isNotBlank(group)) {
            where.append(" AND a.group_id=? ");
        }
        if (StringUtils.isNotBlank(appName)) {
            where.append(" AND a.app_name=? ");
        }
        where.append(" AND b.tag_name IN (");
        for (int i = 0; i < tagSize; i++) {
            if (i != 0) {
                where.append(", ");
            }
            where.append('?');
        }
        where.append(") ");
        return sqlCount + where;
    }

    public String findConfigInfo4PageFetchRows(Map<String, String> params, int tagSize, int startRow, int pageSize) {
        final String appName = params.get("appName");
        final String dataId = params.get("dataId");
        final String group = params.get("group");
        StringBuilder where = new StringBuilder(" WHERE ");
        final String sql = "SELECT a.id,a.data_id,a.group_id,a.tenant_id,a.app_name,a.content FROM config_info  a LEFT JOIN "
                + "config_tags_relation b ON a.id=b.id";

        where.append(" a.tenant_id=? ");

        if (StringUtils.isNotBlank(dataId)) {
            where.append(" AND a.data_id=? ");
        }
        if (StringUtils.isNotBlank(group)) {
            where.append(" AND a.group_id=? ");
        }
        if (StringUtils.isNotBlank(appName)) {
            where.append(" AND a.app_name=? ");
        }

        where.append(" AND b.tag_name IN (");
        for (int i = 0; i < tagSize; i++) {
            if (i != 0) {
                where.append(", ");
            }
            where.append('?');
        }
        where.append(") ");
        return sql + where + " LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String findConfigInfoLike4PageCountRows(final Map<String, String> params, int tagSize) {
        final String appName = params.get("appName");
        final String content = params.get("content");
        final String dataId = params.get("dataId");
        final String group = params.get("group");
        StringBuilder where = new StringBuilder(" WHERE ");
        final String sqlCountRows = "SELECT count(*) FROM config_info  a LEFT JOIN config_tags_relation b ON a.id=b.id ";

        where.append(" a.tenant_id LIKE ? ");
        if (!StringUtils.isBlank(dataId)) {
            where.append(" AND a.data_id LIKE ? ");
        }
        if (!StringUtils.isBlank(group)) {
            where.append(" AND a.group_id LIKE ? ");
        }
        if (!StringUtils.isBlank(appName)) {
            where.append(" AND a.app_name = ? ");
        }
        if (!StringUtils.isBlank(content)) {
            where.append(" AND a.content LIKE ? ");
        }

        where.append(" AND b.tag_name IN (");
        for (int i = 0; i < tagSize; i++) {
            if (i != 0) {
                where.append(", ");
            }
            where.append('?');
        }
        where.append(") ");
        return sqlCountRows + where;
    }

    public String findConfigInfoLike4PageFetchRows(final Map<String, String> params, int tagSize, int startRow,
                                                   int pageSize) {
        final String appName = params.get("appName");
        final String content = params.get("content");
        final String dataId = params.get("dataId");
        final String group = params.get("group");
        StringBuilder where = new StringBuilder(" WHERE ");
        final String sqlFetchRows = "SELECT a.id,a.data_id,a.group_id,a.tenant_id,a.app_name,a.content "
                + "FROM config_info a LEFT JOIN config_tags_relation b ON a.id=b.id ";

        where.append(" a.tenant_id LIKE ? ");
        if (!StringUtils.isBlank(dataId)) {
            where.append(" AND a.data_id LIKE ? ");
        }
        if (!StringUtils.isBlank(group)) {
            where.append(" AND a.group_id LIKE ? ");
        }
        if (!StringUtils.isBlank(appName)) {
            where.append(" AND a.app_name = ? ");
        }
        if (!StringUtils.isBlank(content)) {
            where.append(" AND a.content LIKE ? ");
        }

        where.append(" AND b.tag_name IN (");
        for (int i = 0; i < tagSize; i++) {
            if (i != 0) {
                where.append(", ");
            }
            where.append('?');
        }
        where.append(") ");
        return sqlFetchRows + where + " LIMIT " + startRow + "," + pageSize;
    }

    public String getTableName() {
        return TableConstant.CONFIG_TAGS_RELATION;
    }

}

　　 3.2.5.AbstractGroupCapacityMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.GroupCapacityMapper;

public abstract class AbstractGroupCapacityMapperCommon extends AbstractMapper implements GroupCapacityMapper {

    public String insertIntoSelect() {
        return "INSERT INTO group_capacity (group_id, quota, `usage`, `max_size`, max_aggr_count, max_aggr_size,gmt_create,"
                + " gmt_modified) SELECT ?, ?, count(*), ?, ?, ?, ?, ? FROM config_info";
    }

    public String insertIntoSelectByWhere() {
        return "INSERT INTO group_capacity (group_id, quota,`usage`, `max_size`, max_aggr_count, max_aggr_size, gmt_create,"
                + " gmt_modified) SELECT ?, ?, count(*), ?, ?, ?, ?, ? FROM config_info WHERE group_id=? AND tenant_id = ''";
    }

    public String incrementUsageByWhereQuotaEqualZero() {
        return "UPDATE group_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE group_id = ? AND `usage` < ? AND quota = 0";
    }

    public String incrementUsageByWhereQuotaNotEqualZero() {
        return "UPDATE group_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE group_id = ? AND `usage` < quota AND quota != 0";
    }

    public String incrementUsageByWhere() {
        return "UPDATE group_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE group_id = ?";
    }

    public String decrementUsageByWhere() {
        return "UPDATE group_capacity SET `usage` = `usage` - 1, gmt_modified = ? WHERE group_id = ? AND `usage` > 0";
    }

    public String updateUsage() {
        return "UPDATE group_capacity SET `usage` = (SELECT count(*) FROM config_info), gmt_modified = ? WHERE group_id = ?";
    }

    public String updateUsageByWhere() {
        return "UPDATE group_capacity SET `usage` = (SELECT count(*) FROM config_info WHERE group_id=? AND tenant_id = ''),"
                + " gmt_modified = ? WHERE group_id= ?";
    }

    public String selectGroupInfoBySize() {
        return "SELECT id, group_id FROM group_capacity WHERE id > ? LIMIT ?";
    }

    public String getTableName() {
        return TableConstant.GROUP_CAPACITY;
    }

}

　　 3.2.6.AbstractHistoryConfigInfoMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.HistoryConfigInfoMapper;

public abstract class AbstractHistoryConfigInfoMapperCommon extends AbstractMapper implements HistoryConfigInfoMapper {

    public String removeConfigHistory() {
        return "DELETE FROM his_config_info WHERE gmt_modified < ? LIMIT ?";
    }

    public String findConfigHistoryCountByTime() {
        return "SELECT count(*) FROM his_config_info WHERE gmt_modified < ?";
    }

    public String findDeletedConfig() {
        return "SELECT DISTINCT data_id, group_id, tenant_id FROM his_config_info WHERE op_type = 'D' AND gmt_modified >= ? AND gmt_modified <= ?";
    }

    public String findConfigHistoryFetchRows() {
        return "SELECT nid,data_id,group_id,tenant_id,app_name,src_ip,src_user,op_type,gmt_create,gmt_modified FROM his_config_info "
                + "WHERE data_id = ? AND group_id = ? AND tenant_id = ? ORDER BY nid DESC";
    }

    public String detailPreviousConfigHistory() {
        return "SELECT nid,data_id,group_id,tenant_id,app_name,content,md5,src_user,src_ip,op_type,gmt_create,gmt_modified "
                + "FROM his_config_info WHERE nid = (SELECT max(nid) FROM his_config_info WHERE id = ?) ";
    }

    public String pageFindConfigHistoryFetchRows(int pageNo, int pageSize) {
        final int offset = (pageNo - 1) * pageSize;
        final int limit = pageSize;
        return  "SELECT nid,data_id,group_id,tenant_id,app_name,src_ip,src_user,op_type,gmt_create,gmt_modified FROM his_config_info "
                + "WHERE data_id = ? AND group_id = ? AND tenant_id = ? ORDER BY nid DESC  LIMIT " + offset + "," + limit;
    }

    public String getTableName() {
        return TableConstant.HIS_CONFIG_INFO;
    }

}

　　 3.2.7.AbstractTenantCapacityMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.TenantCapacityMapper;

public abstract class AbstractTenantCapacityMapperCommon extends AbstractMapper implements TenantCapacityMapper {

    public String incrementUsageWithDefaultQuotaLimit() {
        return "UPDATE tenant_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE tenant_id = ? AND `usage` <"
                + " ? AND quota = 0";
    }

    public String incrementUsageWithQuotaLimit() {
        return "UPDATE tenant_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE tenant_id = ? AND `usage` < "
                + "quota AND quota != 0";
    }

    public String incrementUsage() {
        return "UPDATE tenant_capacity SET `usage` = `usage` + 1, gmt_modified = ? WHERE tenant_id = ?";
    }

    public String decrementUsage() {
        return "UPDATE tenant_capacity SET `usage` = `usage` - 1, gmt_modified = ? WHERE tenant_id = ? AND `usage` > 0";
    }

    public String correctUsage() {
        return "UPDATE tenant_capacity SET `usage` = (SELECT count(*) FROM config_info WHERE tenant_id = ?), "
                + "gmt_modified = ? WHERE tenant_id = ?";
    }

    public String getCapacityList4CorrectUsage() {
        return "SELECT id, tenant_id FROM tenant_capacity WHERE id>? LIMIT ?";
    }

    public String insertTenantCapacity() {
        return "INSERT INTO tenant_capacity (tenant_id, quota, `usage`, `max_size`, max_aggr_count, max_aggr_size, "
                + "gmt_create, gmt_modified) SELECT ?, ?, count(*), ?, ?, ?, ?, ? FROM config_info WHERE tenant_id=?;";
    }

    public String getTableName() {
        return TableConstant.TENANT_CAPACITY;
    }

}

　　 3.2.8.AbstractConfigInfoMapperCommon

package com.alibaba.nacos.plugin.datasource.impl.common;

import com.alibaba.nacos.common.utils.CollectionUtils;
import com.alibaba.nacos.common.utils.StringUtils;
import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.ConfigInfoMapper;

import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

public abstract class AbstractConfigInfoMapperCommon extends AbstractMapper implements ConfigInfoMapper {

    private static final String DATA_ID = "dataId";

    private static final String GROUP = "group";

    private static final String APP_NAME = "appName";

    private static final String CONTENT = "content";

    private static final String TENANT = "tenant";

    public String findConfigMaxId() {
        return "SELECT MAX(id) FROM config_info";
    }

    public String findAllDataIdAndGroup() {
        return "SELECT DISTINCT data_id, group_id FROM config_info";
    }

    public String findConfigInfoByAppCountRows() {
        return "SELECT count(*) FROM config_info WHERE tenant_id LIKE ? AND app_name= ?";
    }

    public String findConfigInfoByAppFetchRows(int startRow, int pageSize) {
        return "SELECT id,data_id,group_id,tenant_id,app_name,content FROM config_info"
                + " WHERE tenant_id LIKE ? AND app_name= ?" + " LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String configInfoLikeTenantCount() {
        return "SELECT count(*) FROM config_info WHERE tenant_id LIKE ?";
    }

    public String getTenantIdList(int startRow, int pageSize) {
        return "SELECT tenant_id FROM config_info WHERE tenant_id != '' GROUP BY tenant_id LIMIT " + pageSize
                + " OFFSET " + startRow;
    }

    public String getGroupIdList(int startRow, int pageSize) {
        return "SELECT group_id FROM config_info WHERE tenant_id ='' GROUP BY group_id LIMIT " + pageSize + " OFFSET "
                + startRow;
    }

    public String findAllConfigKey(int startRow, int pageSize) {
        return " SELECT data_id,group_id,app_name  FROM ( "
                + " SELECT id FROM config_info WHERE tenant_id LIKE ? ORDER BY id LIMIT " + pageSize + " OFFSET "
                + startRow + " )" + " g, config_info t WHERE g.id = t.id  ";
    }

    public String findAllConfigInfoBaseFetchRows(int startRow, int pageSize) {
        return "SELECT t.id,data_id,group_id,content,md5"
                + " FROM ( SELECT id FROM config_info ORDER BY id LIMIT ?,?  ) "
                + " g, config_info t  WHERE g.id = t.id ";
    }

    public String findAllConfigInfoFragment(int startRow, int pageSize) {
        return "SELECT id,data_id,group_id,tenant_id,app_name,content,md5,gmt_modified,type,encrypted_data_key "
                + "FROM config_info WHERE id > ? ORDER BY id ASC LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String findChangeConfig() {
        return "SELECT data_id, group_id, tenant_id, app_name, content, gmt_modified,encrypted_data_key "
                + "FROM config_info WHERE gmt_modified >= ? AND gmt_modified <= ?";
    }

    public String findChangeConfigCountRows(Map<String, String> params, final Timestamp startTime,
                                            final Timestamp endTime) {
        final String tenant = params.get(TENANT);
        final String dataId = params.get(DATA_ID);
        final String group = params.get(GROUP);
        final String appName = params.get(APP_NAME);
        final String tenantTmp = StringUtils.isBlank(tenant) ? StringUtils.EMPTY : tenant;
        final String sqlCountRows = "SELECT count(*) FROM config_info WHERE ";
        String where = " 1=1 ";
        if (!StringUtils.isBlank(dataId)) {
            where += " AND data_id LIKE ? ";
        }
        if (!StringUtils.isBlank(group)) {
            where += " AND group_id LIKE ? ";
        }

        if (!StringUtils.isBlank(tenantTmp)) {
            where += " AND tenant_id = ? ";
        }

        if (!StringUtils.isBlank(appName)) {
            where += " AND app_name = ? ";
        }
        if (startTime != null) {
            where += " AND gmt_modified >=? ";
        }
        if (endTime != null) {
            where += " AND gmt_modified <=? ";
        }
        return sqlCountRows + where;
    }

    public String findChangeConfigFetchRows(Map<String, String> params, final Timestamp startTime,
                                            final Timestamp endTime, int startRow, int pageSize, long lastMaxId) {
        final String tenant = params.get(TENANT);
        final String dataId = params.get(DATA_ID);
        final String group = params.get(GROUP);
        final String appName = params.get(APP_NAME);
        final String tenantTmp = StringUtils.isBlank(tenant) ? StringUtils.EMPTY : tenant;
        final String sqlFetchRows = "SELECT id,data_id,group_id,tenant_id,app_name,content,type,md5,gmt_modified FROM config_info WHERE ";
        String where = " 1=1 ";
        if (!StringUtils.isBlank(dataId)) {
            where += " AND data_id LIKE ? ";
        }
        if (!StringUtils.isBlank(group)) {
            where += " AND group_id LIKE ? ";
        }

        if (!StringUtils.isBlank(tenantTmp)) {
            where += " AND tenant_id = ? ";
        }

        if (!StringUtils.isBlank(appName)) {
            where += " AND app_name = ? ";
        }
        if (startTime != null) {
            where += " AND gmt_modified >=? ";
        }
        if (endTime != null) {
            where += " AND gmt_modified <=? ";
        }
        return sqlFetchRows + where + " AND id > " + lastMaxId + " ORDER BY id ASC" + " LIMIT " + 0 + " OFFSET "
                + pageSize;
    }

    public String listGroupKeyMd5ByPageFetchRows(int startRow, int pageSize) {
        return "SELECT t.id,data_id,group_id,tenant_id,app_name,md5,type,gmt_modified,encrypted_data_key FROM "
                + "( SELECT id FROM config_info ORDER BY id LIMIT " + pageSize + " OFFSET " + startRow
                + " ) g, config_info t WHERE g.id = t.id";
    }

    public String findAllConfigInfo4Export(List<Long> ids, Map<String, String> params) {
        String tenant = params.get("tenant");
        String tenantTmp = StringUtils.isBlank(tenant) ? StringUtils.EMPTY : tenant;
        String sql = "SELECT id,data_id,group_id,tenant_id,app_name,content,type,md5,gmt_create,gmt_modified,src_user,src_ip,"
                + "c_desc,c_use,effect,c_schema,encrypted_data_key FROM config_info";
        StringBuilder where = new StringBuilder(" WHERE ");
        List<Object> paramList = new ArrayList<>();
        if (!CollectionUtils.isEmpty(ids)) {
            where.append(" id IN (");
            for (int i = 0; i < ids.size(); i++) {
                if (i != 0) {
                    where.append(", ");
                }
                where.append('?');
                paramList.add(ids.get(i));
            }
            where.append(") ");
        } else {
            where.append(" tenant_id= ? ");
            paramList.add(tenantTmp);
            if (!StringUtils.isBlank(params.get(DATA_ID))) {
                where.append(" AND data_id LIKE ? ");
            }
            if (StringUtils.isNotBlank(params.get(GROUP))) {
                where.append(" AND group_id= ? ");
            }
            if (StringUtils.isNotBlank(params.get(APP_NAME))) {
                where.append(" AND app_name= ? ");
            }
        }
        return sql + where;
    }

    public String findConfigInfoBaseLikeCountRows(Map<String, String> params) {
        final String sqlCountRows = "SELECT count(*) FROM config_info WHERE ";
        String where = " 1=1 AND tenant_id='' ";

        if (!StringUtils.isBlank(params.get(DATA_ID))) {
            where += " AND data_id LIKE ? ";
        }
        if (!StringUtils.isBlank(params.get(GROUP))) {
            where += " AND group_id LIKE ";
        }
        if (!StringUtils.isBlank(params.get(CONTENT))) {
            where += " AND content LIKE ? ";
        }
        return sqlCountRows + where;
    }

    public String findConfigInfoBaseLikeFetchRows(Map<String, String> params, int startRow, int pageSize) {
        final String sqlFetchRows = "SELECT id,data_id,group_id,tenant_id,content FROM config_info WHERE ";
        String where = " 1=1 AND tenant_id='' ";
        if (!StringUtils.isBlank(params.get(DATA_ID))) {
            where += " AND data_id LIKE ? ";
        }
        if (!StringUtils.isBlank(params.get(GROUP))) {
            where += " AND group_id LIKE ";
        }
        if (!StringUtils.isBlank(params.get(CONTENT))) {
            where += " AND content LIKE ? ";
        }
        return sqlFetchRows + where + " LIMIT " + startRow + "," + pageSize;
    }

    public String findConfigInfo4PageCountRows(Map<String, String> params) {
        final String appName = params.get(APP_NAME);
        final String dataId = params.get(DATA_ID);
        final String group = params.get(GROUP);
        final String sqlCount = "SELECT count(*) FROM config_info";
        StringBuilder where = new StringBuilder(" WHERE ");
        where.append(" tenant_id=? ");
        if (StringUtils.isNotBlank(dataId)) {
            where.append(" AND data_id=? ");
        }
        if (StringUtils.isNotBlank(group)) {
            where.append(" AND group_id=? ");
        }
        if (StringUtils.isNotBlank(appName)) {
            where.append(" AND app_name=? ");
        }
        return sqlCount + where;
    }

    public String findConfigInfo4PageFetchRows(Map<String, String> params, int startRow, int pageSize) {
        final String appName = params.get(APP_NAME);
        final String dataId = params.get(DATA_ID);
        final String group = params.get(GROUP);
        final String sql = "SELECT id,data_id,group_id,tenant_id,app_name,content,type,encrypted_data_key FROM config_info";
        StringBuilder where = new StringBuilder(" WHERE ");
        where.append(" tenant_id=? ");
        if (StringUtils.isNotBlank(dataId)) {
            where.append(" AND data_id=? ");
        }
        if (StringUtils.isNotBlank(group)) {
            where.append(" AND group_id=? ");
        }
        if (StringUtils.isNotBlank(appName)) {
            where.append(" AND app_name=? ");
        }
        return sql + where + " LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String findConfigInfoBaseByGroupFetchRows(int startRow, int pageSize) {
        return "SELECT id,data_id,group_id,content FROM config_info WHERE group_id=? AND tenant_id=?" + " LIMIT "
                + pageSize + " OFFSET " + startRow;
    }

    public String findConfigInfoLike4PageCountRows(Map<String, String> params) {
        String dataId = params.get(DATA_ID);
        String group = params.get(GROUP);
        final String appName = params.get(APP_NAME);
        final String content = params.get(CONTENT);
        final String sqlCountRows = "SELECT count(*) FROM config_info";
        StringBuilder where = new StringBuilder(" WHERE ");
        where.append(" tenant_id LIKE ? ");
        if (!StringUtils.isBlank(dataId)) {
            where.append(" AND data_id LIKE ? ");
        }
        if (!StringUtils.isBlank(group)) {
            where.append(" AND group_id LIKE ? ");
        }
        if (!StringUtils.isBlank(appName)) {
            where.append(" AND app_name = ? ");
        }
        if (!StringUtils.isBlank(content)) {
            where.append(" AND content LIKE ? ");
        }
        return sqlCountRows + where;
    }

    public String findConfigInfoLike4PageFetchRows(Map<String, String> params, int startRow, int pageSize) {
        String dataId = params.get(DATA_ID);
        String group = params.get(GROUP);
        final String appName = params.get(APP_NAME);
        final String content = params.get(CONTENT);
        final String sqlFetchRows = "SELECT id,data_id,group_id,tenant_id,app_name,content,encrypted_data_key FROM config_info";
        StringBuilder where = new StringBuilder(" WHERE ");
        where.append(" tenant_id LIKE ? ");
        if (!StringUtils.isBlank(dataId)) {
            where.append(" AND data_id LIKE ? ");
        }
        if (!StringUtils.isBlank(group)) {
            where.append(" AND group_id LIKE ? ");
        }
        if (!StringUtils.isBlank(appName)) {
            where.append(" AND app_name = ? ");
        }
        if (!StringUtils.isBlank(content)) {
            where.append(" AND content LIKE ? ");
        }
        return sqlFetchRows + where + " LIMIT " + pageSize + " OFFSET " + startRow;
    }

    public String findAllConfigInfoFetchRows(int startRow, int pageSize) {
        return "SELECT t.id,data_id,group_id,tenant_id,app_name,content,md5 "
                + " FROM (  SELECT id FROM config_info WHERE tenant_id LIKE ? ORDER BY id LIMIT " + pageSize
                + " OFFSET " + startRow + " )" + " g, config_info t  WHERE g.id = t.id ";
    }

    public String findConfigInfosByIds(int idSize) {
        StringBuilder sql = new StringBuilder(
                "SELECT ID,data_id,group_id,tenant_id,app_name,content,md5 FROM config_info WHERE ");
        sql.append("id IN (");
        for (int i = 0; i < idSize; i++) {
            if (i != 0) {
                sql.append(", ");
            }
            sql.append('?');
        }
        sql.append(") ");
        return sql.toString();
    }

    public String removeConfigInfoByIdsAtomic(int size) {
        StringBuilder sql = new StringBuilder("DELETE FROM config_info WHERE ");
        sql.append("id IN (");
        for (int i = 0; i < size; i++) {
            if (i != 0) {
                sql.append(", ");
            }
            sql.append('?');
        }
        sql.append(") ");
        return sql.toString();
    }

    public String updateConfigInfoAtomicCas() {
        return "UPDATE config_info SET "
                + "content=?, md5 = ?, src_ip=?,src_user=?,gmt_modified=?, app_name=?,c_desc=?,c_use=?,effect=?,type=?,c_schema=? "
                + "WHERE data_id=? AND group_id=? AND tenant_id=? AND (md5=? OR md5 IS NULL OR md5='')";
    }

    public String getTableName() {
        return TableConstant.CONFIG_INFO;
    }

}

　　3.3.达梦数据源适配实现

　　 3.3.1.ConfigInfoAggrMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractConfigInfoAggrMapperCommon;

public class ConfigInfoAggrMapperByDM extends AbstractConfigInfoAggrMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.2.ConfigInfoBetaMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractConfigInfoBetaMapperCommon;

public class ConfigInfoBetaMapperByDM extends AbstractConfigInfoBetaMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.3.ConfigInfoMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractConfigInfoMapperCommon;

public class ConfigInfoMapperByDM extends AbstractConfigInfoMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.4.ConfigInfoTagMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractConfigInfoTagMapperCommon;

public class ConfigInfoTagMapperByDM extends AbstractConfigInfoTagMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.5.ConfigTagsRelationMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractConfigTagsRelationMapperCommon;

public class ConfigTagsRelationMapperByDM extends AbstractConfigTagsRelationMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.6.GroupCapacityMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractGroupCapacityMapperCommon;

public class GroupCapacityMapperByDM extends AbstractGroupCapacityMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.7.HistoryConfigInfoMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractHistoryConfigInfoMapperCommon;

public class HistoryConfigInfoMapperByDM extends AbstractHistoryConfigInfoMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.8.TenantCapacityMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.impl.common.AbstractTenantCapacityMapperCommon;

public class TenantCapacityMapperByDM extends AbstractTenantCapacityMapperCommon {

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }
}

　　 3.3.9.TenantInfoMapperByDM

package com.alibaba.nacos.plugin.datasource.impl.dm;

import com.alibaba.nacos.plugin.datasource.constants.DataSourceConstant;
import com.alibaba.nacos.plugin.datasource.constants.TableConstant;
import com.alibaba.nacos.plugin.datasource.mapper.AbstractMapper;
import com.alibaba.nacos.plugin.datasource.mapper.TenantInfoMapper;

public class TenantInfoMapperByDM  extends AbstractMapper implements TenantInfoMapper {

    @Override
    public String getTableName() {
        return TableConstant.TENANT_INFO;
    }

    @Override
    public String getDataSource() {
        return DataSourceConstant.DM;
    }

}

　　3.4.其他数据源适配实现

　　跟上面达梦数据源适配实现一致，只需将 getDataSource 方法替换成对应的数据源类型就OK；

　　3.5.service文件

　　在resources下面创建resources/META-INF/services/com.alibaba.nacos.plugin.datasource.mapper.Mapper文件

com.alibaba.nacos.plugin.datasource.impl.dm.ConfigInfoAggrMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.ConfigInfoBetaMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.ConfigInfoMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.ConfigInfoTagMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.ConfigTagsRelationMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.GroupCapacityMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.HistoryConfigInfoMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.TenantCapacityMapperByDM
com.alibaba.nacos.plugin.datasource.impl.dm.TenantInfoMapperByDM

#其他类似..............

　　3.6.nacos-server配置

　　1）mvn install后该jar包放入到Nacos（版本2.2.0才支持数据源插件化）的plugins目录下（没有则新建），Nacos的启动脚本startup.sh中-Dloader.path参数将会加载外部jar包文件到Nacos的环境中；

　　2）修改Nacos的conf/application.properties，增加对应数据源的连接参数信息：

db.num=1
#指定数据源类型，对应DataSourceConstant参数
spring.sql.init.platform=dm
db.url.0=jdbc:dm://ip:5236/
db.user.0=username
db.password.0=password
#指定driver
db.pool.config.driverClassName=dm.jdbc.driver.DmDriver

　　3.7.启动

　　1）启动命令：

　　 单机模式：sudo sh startup.sh -m standalone

　　集群模式：./startup.sh

　　PS:

　　集群模式下修改cluster.conf.example文件为cluster.conf，不然报错误： Caused by: com.alibaba.nacos.api.exception.NacosException: java.net.UnknownHostException: jmenv.tbsite.net

　　2）ip访问验证：http://ip:8848/nacos/index.html

二.源码探究

　　1.准备

　　源码nacos-2.2.0：https://github.com/alibaba/nacos.git

　　2.网页入口

　　nacos-console模块com.alibaba.nacos.Nacos

　　3.nacos数据持久化入口

　　 3.1.com.alibaba.nacos.config.server.service.repository.extrnal.ExternalStoragePersistServiceImpl#init()

    @PostConstruct
    public void init() {
        //获取数据源
        dataSourceService = DynamicDataSource.getInstance().getDataSource();

        jt = getJdbcTemplate();
        tjt = getTransactionTemplate();
        Boolean isDataSourceLogEnable = EnvUtil
                .getProperty(Constants.NACOS_PLUGIN_DATASOURCE_LOG, Boolean.class, false);
        mapperManager = MapperManager.instance(isDataSourceLogEnable);
    }

    com.alibaba.nacos.config.server.service.datasource.DynamicDataSource#getDataSource
        public synchronized DataSourceService getDataSource() {
        try {

            // Embedded storage is used by default in stand-alone mode
            // In cluster mode, external databases are used by default
            //单机模式
            if (PropertyUtil.isEmbeddedStorage()) {
                if (localDataSourceService == null) {
                    localDataSourceService = new LocalDataSourceServiceImpl();
                    localDataSourceService.init();
                }
                return localDataSourceService;
            } else {
                //集群模式
                if (basicDataSourceService == null) {
                    basicDataSourceService = new ExternalDataSourceServiceImpl();
                    basicDataSourceService.init();
                }
                return basicDataSourceService;
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

　　 3.2.com.alibaba.nacos.config.server.service.datasource.ExternalDataSourceServiceImpl#init

        @Override
    public void init() {
        queryTimeout = ConvertUtils.toInt(System.getProperty("QUERYTIMEOUT"), 3);
        jt = new JdbcTemplate();
        // Set the maximum number of records to prevent memory expansion
        jt.setMaxRows(50000);
        jt.setQueryTimeout(queryTimeout);

        testMasterJT = new JdbcTemplate();
        testMasterJT.setQueryTimeout(queryTimeout);

        testMasterWritableJT = new JdbcTemplate();
        // Prevent the login interface from being too long because the main library is not available
        testMasterWritableJT.setQueryTimeout(1);

        //  Database health check

        testJtList = new ArrayList<>();
        isHealthList = new ArrayList<>();

        tm = new DataSourceTransactionManager();
        tjt = new TransactionTemplate(tm);

        // Transaction timeout needs to be distinguished from ordinary operations.
        tjt.setTimeout(TRANSACTION_QUERY_TIMEOUT);
        //获取数据源类型:spring.sql.init.platform或spring.datasource.platform指定的参数值
        dataSourceType = DatasourcePlatformUtil.getDatasourcePlatform(defaultDataSourceType);

        if (PropertyUtil.isUseExternalDB()) {
            try {
                //加载数据源连接
                reload();
            } catch (IOException e) {
                FATAL_LOG.error("[ExternalDataSourceService] datasource reload error", e);
                throw new RuntimeException(DB_LOAD_ERROR_MSG, e);
            }

            if (this.dataSourceList.size() > DB_MASTER_SELECT_THRESHOLD) {
                ConfigExecutor.scheduleConfigTask(new SelectMasterTask(), 10, 10, TimeUnit.SECONDS);
            }
            ConfigExecutor.scheduleConfigTask(new CheckDbHealthTask(), 10, 10, TimeUnit.SECONDS);
        }
    }

　　 3.3.com.alibaba.nacos.config.server.service.datasource.ExternalDataSourceServiceImpl#reload

@Override
    public synchronized void reload() throws IOException {
        try {
            final List<JdbcTemplate> testJtListNew = new ArrayList<JdbcTemplate>();
            final List<Boolean> isHealthListNew = new ArrayList<Boolean>();
            //com.alibaba.nacos.config.server.service.datasource.ExternalDataSourceProperties#build：获取数据源
            List<HikariDataSource> dataSourceListNew = new ExternalDataSourceProperties()
                    .build(EnvUtil.getEnvironment(), (dataSource) -> {
                        JdbcTemplate jdbcTemplate = new JdbcTemplate();
                        jdbcTemplate.setQueryTimeout(queryTimeout);
                        jdbcTemplate.setDataSource(dataSource);
                        testJtListNew.add(jdbcTemplate);
                        isHealthListNew.add(Boolean.TRUE);
                    });
            final List<HikariDataSource> dataSourceListOld = dataSourceList;
            final List<JdbcTemplate> testJtListOld = testJtList;
            dataSourceList = dataSourceListNew;
            testJtList = testJtListNew;
            isHealthList = isHealthListNew;
            //选择主数据源：测试数据源，数据源设置到JdbcTemplate jt中（重点，后续请求从jt中获取dataSource）
            new SelectMasterTask().run();
            //校验数据源的状态
            new CheckDbHealthTask().run();

            //close old datasource.
            if (dataSourceListOld != null && !dataSourceListOld.isEmpty()) {
                for (HikariDataSource dataSource : dataSourceListOld) {
                    dataSource.close();
                }
            }
            if (testJtListOld != null && !testJtListOld.isEmpty()) {
                for (JdbcTemplate oldJdbc : testJtListOld) {
                    oldJdbc.setDataSource(null);
                }
            }
        } catch (RuntimeException e) {
            FATAL_LOG.error(DB_LOAD_ERROR_MSG, e);
            throw new IOException(e);
        }
    }

　　 3.4.com.alibaba.nacos.config.server.service.datasource.ExternalDataSourceProperties#build：根据application.properties配置连接获取数据源

    List<HikariDataSource> build(Environment environment, Callback<HikariDataSource> callback) {
        List<HikariDataSource> dataSources = new ArrayList<>();
        Binder.get(environment).bind("db", Bindable.ofInstance(this));
        Preconditions.checkArgument(Objects.nonNull(num), "db.num is null");
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(user), "db.user or db.user.[index] is null");
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(password), "db.password or db.password.[index] is null");
        for (int index = 0; index < num; index++) {
            int currentSize = index + 1;
            Preconditions.checkArgument(url.size() >= currentSize, "db.url.%s is null", index);
            //获取driverClassName
            DataSourcePoolProperties poolProperties = DataSourcePoolProperties.build(environment);
            if (StringUtils.isEmpty(poolProperties.getDataSource().getDriverClassName())) {
                poolProperties.setDriverClassName(JDBC_DRIVER_NAME);
            }
            poolProperties.setJdbcUrl(url.get(index).trim());
            poolProperties.setUsername(getOrDefault(user, index, user.get(0)).trim());
            poolProperties.setPassword(getOrDefault(password, index, password.get(0)).trim());
            HikariDataSource ds = poolProperties.getDataSource();
            if (StringUtils.isEmpty(ds.getConnectionTestQuery())) {
                ds.setConnectionTestQuery(TEST_QUERY);
            }
            dataSources.add(ds);
            callback.accept(ds);
        }
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(dataSources), "no datasource available");
        return dataSources;
    }

　　 3.5.com.alibaba.nacos.config.server.service.datasource.DataSourcePoolProperties#build

        public static DataSourcePoolProperties build(Environment environment) {
        DataSourcePoolProperties result = new DataSourcePoolProperties();
        //绑定driverClassName值
        Binder.get(environment).bind("db.pool.config", Bindable.ofInstance(result.getDataSource()));
        return result;
    }

　　 3.6.com.alibaba.nacos.plugin.datasource.MapperManager#loadInitial：nacos-datasource-plugin

    public void loadInitial() {
        //spi加载插件实现类
        Collection<Mapper> mappers = NacosServiceLoader.load(Mapper.class);
        for (Mapper mapper : mappers) {
            Map<String, Mapper> mapperMap = MAPPER_SPI_MAP.getOrDefault(mapper.getDataSource(), new HashMap<>(16));
            mapperMap.put(mapper.getTableName(), mapper);
            MAPPER_SPI_MAP.put(mapper.getDataSource(), mapperMap);
            LOGGER.info("[MapperManager] Load Mapper({}) datasource({}) tableName({}) successfully.",
                    mapper.getClass(), mapper.getDataSource(), mapper.getTableName());
        }
    }

　　ps:

　　SPI：Service Provider Interface （服务提供接口） 是java提供的一套用来被第三方实现或扩展的接口。它可以用来启用框架 扩展和替换 组件；

　　SPI 与API 区别与联系

　　　　API: (Application Programming Interface) 在绝大多数情况下，都是实现方定制接口并进行接口的实现，调用者只能选择调用，而无权选择不同实现；

　　　　SPI: 调用方制定接口规范，提供给外部实现。调用方在调用时选择自己需要的外部实现；

　　流程：

　　1）定义一个接口，定义接口的实现类；

　　2）在resources目录下新建META-INF/services目录，并且在这个目录下新建一个与上述接口的全限定名一致的文件，在这个文件中写入接口的实现类的全限定名；

　　3）通过serviceLoader加载实现类并调用

  public static void main(String[] args) {
         ServiceLoader<Mapper> mappers = ServiceLoader.load(Mapper.class);
         for (Mapper m : mappers) {
             m.getTableName();
         }
     }

　　pps：在 ServiceLoader.load 后遍历 mappers 时可以通过 BeanDefinitionRegistry 可以将mapper实现类注册到 ApplicationContext中，这样就可以对接口实现类使用 @Autowired 来解决依赖注入问题了；

　　 3.7.com.alibaba.nacos.config.server.service.dump.ExternalDumpService#init：将数据库的config_info信息dump一份到本地磁盘

    @PostConstruct
    @Override
    protected void init() throws Throwable {
        dumpOperate(processor, dumpAllProcessor, dumpAllBetaProcessor, dumpAllTagProcessor);
    }

　　ps：

　　有兴趣可研究 ExternalDumpService#init -> DumpService#dumpConfigInfo -> DumpAllProcessor#process(第一行定位到3.8) -> ExternalStoragePersistServiceImpl#findAllConfigInfoFragment -> 分页将数据库的config_info（nacos的配置管理的配置列表信息）dump到本地磁盘 -> ConfigCacheService#dump -> DiskUtil#saveToDisk

　　pps：所以nacos的配置信息优先从本地取，本地为空再从数据库取并更新到本地；

　　可从 ConfigController#getConfig -> ConfigServletInner#doGetConfig() 中看到从本地缓存取，失败再从数据库查询并更新到本地；

　　 3.8.com.alibaba.nacos.config.server.service.repository.extrnal.ExternalConfigInfoPersistServiceImpl#findConfigMaxId

public long findConfigMaxId() {
        //获取config_info表实现类
        ConfigInfoMapper configInfoMapper = mapperManager.findMapper(dataSourceService.getDataSourceType(),
                TableConstant.CONFIG_INFO);
        String sql = configInfoMapper.findConfigMaxId();
        try {
            return jt.queryForObject(sql, Long.class);
        } catch (NullPointerException e) {
            return 0;
        }
    }

　　 3.9.com.alibaba.nacos.plugin.datasource.MapperManager#findMapper

public <R extends Mapper> R findMapper(String dataSource, String tableName) {
        LOGGER.info("[MapperManager] findMapper dataSource: {}, tableName: {}", dataSource, tableName);
        if (StringUtils.isBlank(dataSource) || StringUtils.isBlank(tableName)) {
            throw new NacosRuntimeException(FIND_DATASOURCE_ERROR_CODE, "dataSource or tableName is null");
        }
        Map<String, Mapper> tableMapper = MAPPER_SPI_MAP.get(dataSource);
        if (Objects.isNull(tableMapper)) {
            throw new NacosRuntimeException(FIND_DATASOURCE_ERROR_CODE,
                    "[MapperManager] Failed to find the datasource,dataSource:" + dataSource);
        }
        Mapper mapper = tableMapper.get(tableName);
        if (Objects.isNull(mapper)) {
            throw new NacosRuntimeException(FIND_TABLE_ERROR_CODE,
                    "[MapperManager] Failed to find the table ,tableName:" + tableName);
        }
        //nacos.plugin.datasource.log.enabled=true开启日志：jdk代理
        if (dataSourceLogEnable) {
            MapperProxy mapperProxy = new MapperProxy();
            return (R) mapperProxy.createProxy(mapper);
        }
        return (R) mapper;
    }