shardingsphere 分庫分表解決方案

本文轉載自查看原文 2021-09-27 21:32 181 mysql

開發背景

多個大表數據均值3-5億，故使用mysql 分庫分表策略水平拆分成小表

工程引入依賴

<!--shardingsphere 分庫分表-->
<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
    <version>${sharding-sphere.version}</version>
</dependency>
<dependency>
    <groupId>org.apache.shardingsphere</groupId>
    <artifactId>sharding-jdbc-spring-namespace</artifactId>
    <version>${sharding-sphere.version}</version>
</dependency>

引入nacos配置

記一次不知原因的問題: 分庫分表的配置 tables 配置三個可用，兩個可用，四個不可用，五個可用。即為了可用性，配置一張虛擬表到五張表配置!!!!!!!!!!

# 數據源
spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: ${MYSQL-USER:ms_wk}
      password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
      url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/${MYSQL-DB:ms_wk}?characterEncoding=utf8&allowPublicKeyRetrieval=true&allowPublicKeyRetrieval=true&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        #login-username: admin
        #login-password: admin
      filter:
        stat:
          enabled: true
          log-slow-sql: true
          slow-sql-millis: 10000
          merge-sql: false
        wall:
          config:
            multi-statement-allow: true
  #sharding-jdbc
  shardingsphere:
    datasource:
      names: history,master,slave1,slave2,mswkhis
      # 主庫
      master:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/${MYSQL-DB:ms_wk}?characterEncoding=utf8&allowPublicKeyRetrieval=true&allowPublicKeyRetrieval=true&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true
        username: ${MYSQL-USER:ms_wk}
        password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
      # 從庫1
      slave1:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/${MYSQL-DB:ms_wk}?characterEncoding=utf8&allowPublicKeyRetrieval=true&allowPublicKeyRetrieval=true&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true
        username: ${MYSQL-USER:ms_wk}
        password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
      # 從庫2
      slave2:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/${MYSQL-DB:ms_wk}?characterEncoding=utf8&allowPublicKeyRetrieval=true&allowPublicKeyRetrieval=true&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true
        username: ${MYSQL-USER:ms_wk}
        password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
      # 歷史數據庫
      history:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/ms_history?serverTimezone=UTC&useSSL=false&useUnicode=true&characterEncoding=UTF-8
        username: ${MYSQL-USER:ms_wk}
        password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
      # 分庫分表數據庫
      mswkhis:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        url: jdbc:mysql://${MYSQL-HOST:msdp-mysql}:${MYSQL-PORT:9306}/ms_wk_his?serverTimezone=UTC&useSSL=false&useUnicode=true&characterEncoding=UTF-8
        username: ${MYSQL-USER:ms_wk}
        password: ENC(cYIdeHxqoBk7BXyBhLliz5YqQLlD5kPs)
    props:
      sql:
        show: true
    # 分片配置
    sharding:
      # 分片讀寫分離配置
      master-slave-rules:
        # 默認主從
        ds_master_slave:
          master-data-source-name: master
          slave-data-source-names: slave1,slave2
        # 分片數據源讀寫分離配置（歷史數據源）
        ds_history:
          master-data-source-name: history
          slave-data-source-names: history
        # 分片數據源讀寫分離配置（分庫分表數據源）
        ds_ms_wk_his:
          master-data-source-name: mswkhis
          slave-data-source-names: mswkhis
      # 未配置分片規則的表將通過默認數據源定位
      default-data-source-name: ds_master_slave
      binding-tables: wk_sync_log
      broadcast-tables: t_address
      tables:
        wk_sync_log:
          actual-data-nodes: ds_history.wk_sync_log_$->{2020..2021}$->{['01','02','03','04','05','06','07','08','09','10','11','12']}$->{['01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29','30','31']}
          key-generator:
            column: jid
            type: UUID
          table-strategy:
            standard:
              precise-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayShardingAlgorithm
              range-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayRangeShardingAlgorithm
              sharding-column: create_time
        wk_atdmac_record:
          actual-data-nodes: ds_history.wk_atdmac_record_$->{2020..2021}$->{['01','02','03','04','05','06','07','08','09','10','11','12']}$->{['01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29','30','31']}
          key-generator:
            column: jid
            type: UUID
          table-strategy:
            standard:
              precise-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayShardingAlgorithm
              range-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayRangeShardingAlgorithm
              sharding-column: show_time
        wk_worker_attendance:
          actual-data-nodes: ds_ms_wk_his.wk_worker_attendance_$->{2020..2021}$->{['01','02','03','04','05','06','07','08','09','10','11','12']}$->{['01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29','30','31']}
          key-generator:
            column: jid
            type: UUID
          table-strategy:
            standard:
              precise-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayShardingAlgorithm
              range-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayRangeShardingAlgorithm
              sharding-column: attend_time
        wk_worker_attend_month:
          actual-data-nodes: ds_ms_wk_his.wk_worker_attend_month_$->{2020..2021}$->{['01','02','03','04','05','06','07','08','09','10','11','12']}$->{['01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24','25','26','27','28','29','30','31']}
          key-generator:
            column: jid
            type: UUID
          table-strategy:
            standard:
              precise-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayShardingAlgorithm
              range-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayRangeShardingAlgorithm
              sharding-column: attend_date  
        t_sharding_bak:
          actual-data-nodes: ds_ms_wk_his.t_sharding_bak_20210101
          key-generator:
            column: jid
            type: UUID
          table-strategy:
            standard:
              precise-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayShardingAlgorithm
              range-algorithm-class-name: com.iyysoft.cloud.msdp.wk.config.shardingsphere.DayRangeShardingAlgorithm
              sharding-column: attend_date

nacos配置

設置分片規則

package com.iyysoft.cloud.msdp.wk.config.shardingsphere;

import com.google.common.collect.Range;
import org.apache.shardingsphere.api.sharding.standard.RangeShardingAlgorithm;
import org.apache.shardingsphere.api.sharding.standard.RangeShardingValue;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.LinkedHashSet;

/**
 * 日期范圍分片
 *
 * @author lvlinguang
 * @date 2020-08-10 19:09
 */
public class DayRangeShardingAlgorithm implements RangeShardingAlgorithm<String> {

    /**
     * 設置分片
     *
     * @param collection
     * @param rangeShardingValue
     * @return
     */
    @Override
    public Collection<String> doSharding(Collection<String> collection, RangeShardingValue<String> rangeShardingValue) {
        Collection<String> result = new LinkedHashSet<>();
        DateFormat sdf = new SimpleDateFormat("yyyyMMdd");
        //日期
        Range<String> ranges = rangeShardingValue.getValueRange();
        Date startTime = dateFormat(ranges.lowerEndpoint());
        Date endTime = dateFormat(ranges.upperEndpoint());

        Calendar cal = Calendar.getInstance();
        while (startTime.getTime() <= endTime.getTime()) {
            String value = sdf.format(startTime);
            for (String each : collection) {
                if (each.endsWith(value)) {
                    result.add(each);
                    break;
                }
            }
            cal.setTime(startTime);
            cal.add(Calendar.DAY_OF_YEAR, 1);
            startTime = cal.getTime();
        }
        if (result.size() == 0) {
            result = collection;
        }
        return result;
    }

    /**
     * 日期轉換
     *
     * @param date
     * @return
     */
    public Date dateFormat(String date) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return sdf.parse(date);
        } catch (ParseException e) {
            return null;
        }
    }
}

DayRangeShardingAlgorithm

package com.iyysoft.cloud.msdp.wk.config.shardingsphere;

import lombok.SneakyThrows;
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingAlgorithm;
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingValue;

import java.text.ParseException;
import java.util.Collection;

/**
 * 日期精確分片
 *
 * @author lvlinguang
 * @date 2020-08-10 19:11
 */
public class DayShardingAlgorithm implements PreciseShardingAlgorithm<String> {

    /**
     * 設置分片
     *
     * @param tableNames    數據表
     * @param shardingValue 分片列信息
     * @return
     */
    @SneakyThrows
    @Override
    public String doSharding(Collection<String> tableNames, PreciseShardingValue<String> shardingValue) {
        String tableName = shardingValue.getLogicTableName();
        String key = getDate(shardingValue.getValue(), 8);
        return tableName.concat("_").concat(key);
    }

    /**
     * 得到日期數字
     *
     * @param date 字符串日期
     * @param len  長度
     * @return 202008
     * @throws ParseException
     */
    public String getDate(String date, int len) throws ParseException {
        String number = date.replaceAll("\\D", "");
        return number.substring(0, len);
    }
}

DayShardingAlgorithm

package com.iyysoft.cloud.msdp.wk.config.shardingsphere;

import com.google.common.collect.Range;
import org.apache.shardingsphere.api.sharding.standard.RangeShardingAlgorithm;
import org.apache.shardingsphere.api.sharding.standard.RangeShardingValue;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Collection;
import java.util.Date;
import java.util.LinkedHashSet;

/**
 * 月范圍分片
 *
 * @author lvlinguang
 * @date 2020-08-10 19:09
 */
public class MonthRangeShardingAlgorithm implements RangeShardingAlgorithm<String> {

    /**
     * 設置分片
     *
     * @param collection
     * @param rangeShardingValue
     * @return
     */
    @Override
    public Collection<String> doSharding(Collection<String> collection, RangeShardingValue<String> rangeShardingValue) {
        Collection<String> result = new LinkedHashSet<>();
        DateFormat sdf = new SimpleDateFormat("yyyyMM");
        //日期
        Range<String> ranges = rangeShardingValue.getValueRange();
        Date startTime = dateFormat(ranges.lowerEndpoint());
        Date endTime = dateFormat(ranges.upperEndpoint());

        Calendar cal = Calendar.getInstance();
        while (startTime.getTime() <= endTime.getTime()) {
            String value = sdf.format(startTime);
            for (String each : collection) {
                if (each.endsWith(value)) {
                    result.add(each);
                    break;
                }
            }
            cal.setTime(startTime);
            cal.add(Calendar.MONTH, 1);
            startTime = cal.getTime();
        }
        if (result.size() == 0) {
            result = collection;
        }
        return result;
    }

    /**
     * 日期轉換
     *
     * @param date
     * @return
     */
    public Date dateFormat(String date) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return sdf.parse(date);
        } catch (ParseException e) {
            return null;
        }
    }
}

MonthRangeShardingAlgorithm

package com.iyysoft.cloud.msdp.wk.config.shardingsphere;

import lombok.SneakyThrows;
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingAlgorithm;
import org.apache.shardingsphere.api.sharding.standard.PreciseShardingValue;

import java.text.ParseException;
import java.util.Collection;

/**
 * 月精確分片
 *
 * @author lvlinguang
 * @date 2020-08-10 19:11
 */
public class MonthShardingAlgorithm implements PreciseShardingAlgorithm<String> {

    /**
     * 設置分片
     *
     * @param tableNames    數據表
     * @param shardingValue 分片列信息
     * @return
     */
    @SneakyThrows
    @Override
    public String doSharding(Collection<String> tableNames, PreciseShardingValue<String> shardingValue) {
        String tableName = shardingValue.getLogicTableName();
        String key = getDate(shardingValue.getValue(), 6);
        return tableName.concat("_").concat(key);
    }

    /**
     * 得到日期數字
     *
     * @param date 字符串日期
     * @param len  長度
     * @return 202008
     * @throws ParseException
     */
    public String getDate(String date, int len) throws ParseException {
        String number = date.replaceAll("\\D", "");
        return number.substring(0, len);
    }
}

MonthShardingAlgorithm

大表數據歸檔

-- 創建定時任務事件
create event his_wk_worker_attendance_joint_event
ON SCHEDULE EVERY 1 DAY STARTS DATE_ADD(DATE_ADD(CURDATE(), INTERVAL 1 DAY), INTERVAL 1 HOUR)
on completion preserve enable
do call his_wk_worker_attendance_joint();

-- 查看定時任務
SELECT event_name,event_definition,interval_value,interval_field,status FROM information_schema.EVENTS;
-- 啟停已經創建好的event(事件)
alter event his_wk_worker_attendance_joint_event on completion preserve enable; -- 開啟定時任務
alter event his_wk_worker_attendance_joint_event on completion preserve disable;-- 關閉定時任務

-- 開啟事件調度器
SET GLOBAL event_scheduler = ON;

-- 關閉事件調度器
SET GLOBAL event_scheduler = OFF;

-- 查看事件調度器狀態
SHOW VARIABLES LIKE 'event_scheduler';

CREATE DEFINER=`croot`@`%` PROCEDURE `his_wk_worker_attendance_joint`()
BEGIN
insert into ms_wk.wk_worker_attendance_joint_his
select * from wk_worker_attendance_joint where create_date < date_sub(now(),interval 5 day);
commit;

delete from ms_wk.wk_worker_attendance_joint where create_date < date_sub(now(),interval 5 day);
commit;
END

數據歸檔存儲過程

大表數據遷移

CREATE DEFINER=`croot`@`%` PROCEDURE `sub_wk_worker_attendance`()
BEGIN


declare x int;
declare y int;
declare z int;
set x=2020;
set y=1;
set z=1;
while x<=2022 do  
    while y<=12 do
        while z<=31 do
            set @sql_create_table_gpstrail = concat(
            'CREATE TABLE IF NOT EXISTS wk_worker_attendance_',lPAD(x,4,'0'),lPAD(y,2,'0'),lPAD(z,2,'0'),
            "(`jid` char(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '在jtg平台的數據id  ',
  `tenant_id` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '所屬租戶',
  `create_id` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '' COMMENT '創建人',
  `create_date` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創建時間',
  `update_id` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '更新人',
  `update_date` datetime NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP COMMENT '更新時間',
  `has_use` char(1) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '是否啟用',
  `has_del` char(1) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT '0' COMMENT '是否刪除',
  `project_jid` char(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '項目id',
  `team_jid` char(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '班組id',
  `worker_jid` char(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '工人id',
  `worker_name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '工人姓名',
  `attend_time` datetime NOT NULL COMMENT '考勤時間',
  `direction` char(2) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '考勤方向 考勤方向字典表:  \r\n1入場  \r\n0出場  ',
  `attend_type` char(3) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '001' COMMENT '通行方式 參考通行方式字典表  :\r\n001 人臉識別\r\n002 虹膜識別\r\n003 指紋識別\r\n004 掌紋識別\r\n005 身份證識別\r\n006 實名卡\r\n007 異常清退（適用於人員沒有通過閘機系統出工地而導致人員狀態不一致的情況）\r\n008 一鍵開閘(需要與閘機交互)\r\n009 應急通道（不需要與閘機交互）\r\n010 二維碼識別\r\n011 其他方式\r\n012系統自動簽出',
  `img_url` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '考勤照片  期望是絕對路徑',
  `lng` decimal(18, 15) NULL DEFAULT NULL COMMENT '經度 WGS84經度',
  `lat` decimal(18, 15) NULL DEFAULT NULL COMMENT '緯度  WGS84緯度',
  `channel` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '通道',
  `attend_source_type` int(3) UNSIGNED NOT NULL DEFAULT 0 COMMENT '考勤數據來源:  0未定義  ,  10個人app考勤 ,  11班組長app考勤  ,  12管工端考勤機模式考勤  ,  20 考勤機考勤 \r\n定義: 1X APP端考勤  , 2X 硬件設備考勤',
  `atdmac_jid` char(36) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL COMMENT '考勤設備jid',
  PRIMARY KEY (`jid`) USING BTREE,
  UNIQUE INDEX `attend_time`(`attend_time`, `project_jid`, `worker_jid`, `has_del`) USING BTREE,
  INDEX `team_jid`(`team_jid`) USING BTREE,
  INDEX `project_jid`(`project_jid`, `worker_jid`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci COMMENT = '工人考勤數據原始記錄' ROW_FORMAT = Dynamic");

                
            PREPARE sql_create_table_gpstrail FROM @sql_create_table_gpstrail;     
            EXECUTE sql_create_table_gpstrail; 
            set z=z+1;
        end while;
        set y=y+1;
        set z=1;
    end while;
    set x= x +1;
    set y=1;
    set z=1;
end while;
END

建表存儲過程

CREATE DEFINER=`croot`@`%` PROCEDURE `insert_wk_worker_attendance`()
BEGIN


declare x int;
declare y int;
declare z int;
set x=2020;
set y=1;
set z=1;
while x<=2022 do  
    while y<=12 do
        while z<=31 do
            set @sql_create_table_gpstrail = concat('insert into ms_wk_his.wk_worker_attendance_',lPAD(x,4,'0'),lPAD(y,2,'0'),lPAD(z,2,'0'),
" select * from  ms_wk.wk_worker_attendance_bak where attend_time BETWEEN '",lPAD(x,4,'0'),"-",lPAD(y,2,'0'),"-",lPAD(z,2,'0')," 00:00:00' AND '",lPAD(x,4,'0'),"-",lPAD(y,2,'0'),"-",lPAD(z,2,'0')," 23:59:59'");
            PREPARE sql_create_table_gpstrail FROM @sql_create_table_gpstrail;     
            EXECUTE sql_create_table_gpstrail; 
            commit;
            set z=z+1;
        end while;
        set y=y+1;
        set z=1;
    end while;
    set x= x +1;
    set y=1;
    set z=1;
end while;
END

數據遷移存儲過程

CREATE DEFINER=`croot`@`%` PROCEDURE `subDBtest`()
BEGIN


declare x int;
declare y int;
declare z int;
set x=2020;
set y=1;
set z=1;
while x<=2022 do  
    while y<=12 do
        while z<=31 do
            select concat(lPAD(x,4,'0'),lPAD(y,2,'0'),lPAD(z,2,'0'));
            set z=z+1;
        end while;
        set y=y+1;
        set z=1;
    end while;
    set x= x +1;
    set y=1;
    set z=1;
end while;
END

存儲過程實例

數據遷移問題走索引 + 存儲過程腳本會快一點

分庫分表引發的問題

分庫分表不支持子查詢
分庫分表不支持mybatis-plus分頁查詢(自帶子查詢)
分庫分表不帶上分表字段，即會查詢所有分表

// 棄用mybatis-plus自帶分頁，手動分頁參考文獻
https://blog.csdn.net/lq2418c/article/details/120039274?utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-3.no_search_link&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7ECTRLIST%7Edefault-3.no_search_link
https://blog.csdn.net/qq_44086060/article/details/116273587

package com.iyysoft.msdp.basic.bean.util;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;


/**
 * @author cjq
 * @date 2021-09-27
 * mybatis-plus 分頁幫助類
 */
@Component
public class PageHelperUtils {
    /**
     * 分頁方法
     *
     * @param currentPage 頁數
     * @param pageSize    分頁大小
     * @param list        分頁對象
     * @return
     */
    public static Page getPages(Integer currentPage, Integer pageSize, List list) {
        Page page = new Page();
        int size = list.size();
        if(size == 0){
            return page.setCurrent(currentPage).setSize(pageSize).setTotal(list.size()).setRecords(list);
        }
        if (pageSize > size) {
            pageSize = size;
        }
        //求出最大頁數，防止currentPage越界
        int maxPage = size % pageSize == 0 ? size / pageSize : size / pageSize + 1;
        if (currentPage > maxPage) {
            currentPage = maxPage;
        }
        //當前頁第一條數據下標
        int curIds = currentPage > 1 ? (currentPage - 1) * pageSize : 0;
        List pageList = new ArrayList<>();
        //將當前頁的數據放進pageList
        for (int i = 0; i < pageSize && curIds + i < size; i++) {
            pageList.add(list.get(curIds + i));
        }
        page.setCurrent(currentPage).setSize(pageSize).setTotal(list.size()).setRecords(pageList);
        return page;
    }
}

PageHelperUtils

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