<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>easyexcel</artifactId>
   <version>3.0.5</version>
</dependency>

CREATE TABLE dept( /*部門表*/
deptno MEDIUMINT   UNSIGNED  NOT NULL  DEFAULT 0,
dname VARCHAR(20)  NOT NULL  DEFAULT "",
loc VARCHAR(13) NOT NULL DEFAULT ""
) ;

#創(chuàng)建表EMP雇員
CREATE TABLE emp
(empno  MEDIUMINT UNSIGNED  NOT NULL  DEFAULT 0, /*編號*/
ename VARCHAR(20) NOT NULL DEFAULT "", /*名字*/
job VARCHAR(9) NOT NULL DEFAULT "",/*工作*/
mgr MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,/*上級編號*/
hiredate DATE NOT NULL,/*入職時間*/
sal DECIMAL(7,2)  NOT NULL,/*薪水*/
comm DECIMAL(7,2) NOT NULL,/*紅利*/
deptno MEDIUMINT UNSIGNED NOT NULL DEFAULT 0 /*部門編號*/
) ;

#工資級別表
CREATE TABLE salgrade
(
grade MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,
losal DECIMAL(17,2)  NOT NULL,
hisal DECIMAL(17,2)  NOT NULL
);

#測試數(shù)據(jù)
INSERT INTO salgrade VALUES (1,700,1200);
INSERT INTO salgrade VALUES (2,1201,1400);
INSERT INTO salgrade VALUES (3,1401,2000);
INSERT INTO salgrade VALUES (4,2001,3000);
INSERT INTO salgrade VALUES (5,3001,9999);

delimiter $$

#創(chuàng)建一個函數(shù)，名字 rand_string，可以隨機(jī)返回我指定的個數(shù)字符串
create function rand_string(n INT)
returns varchar(255) #該函數(shù)會返回一個字符串
begin
#定義了一個變量 chars_str， 類型  varchar(100)
#默認(rèn)給 chars_str 初始值   'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ'
 declare chars_str varchar(100) default
   'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ'; 
 declare return_str varchar(255) default '';
 declare i int default 0; 
 while i < n do
    # concat 函數(shù) : 連接函數(shù)mysql函數(shù)
   set return_str =concat(return_str,substring(chars_str,floor(1+rand()*52),1));
   set i = i + 1;
   end while;
  return return_str;
  end $$


 #這里我們又自定了一個函數(shù),返回一個隨機(jī)的部門號
create function rand_num( )
returns int(5)
begin
declare i int default 0;
set i = floor(10+rand()*500);
return i;
end $$

 #創(chuàng)建一個存儲過程， 可以添加雇員
create procedure insert_emp(in start int(10),in max_num int(10))
begin
declare i int default 0;
#set autocommit =0 把a(bǔ)utocommit設(shè)置成0
 #autocommit = 0 含義: 不要自動提交
 set autocommit = 0; #默認(rèn)不提交sql語句
 repeat
 set i = i + 1;
 #通過前面寫的函數(shù)隨機(jī)產(chǎn)生字符串和部門編號，然后加入到emp表
 insert into emp values ((start+i) ,rand_string(6),'SALESMAN',0001,curdate(),2000,400,rand_num());
  until i = max_num
 end repeat;
 #commit整體提交所有sql語句，提高效率
   commit;
 end $$

 #添加8000000數(shù)據(jù)
call insert_emp(100001,8000000)$$

#命令結(jié)束符，再重新設(shè)置為;
delimiter ;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Emp implements Serializable {
    @ExcelProperty(value = "員工編號")
    private Integer empno;

    @ExcelProperty(value = "員工名稱")
    private String ename;

    @ExcelProperty(value = "工作")
    private String job;

    @ExcelProperty(value = "主管編號")
    private Integer mgr;

    @ExcelProperty(value = "入職日期")
    private Date hiredate;

    @ExcelProperty(value = "薪資")
    private BigDecimal sal;

    @ExcelProperty(value = "獎金")
    private BigDecimal comm;

    @ExcelProperty(value = "所屬部門")
    private Integer deptno;

}

@Data
public class EmpVo {

    @ExcelProperty(value = "員工編號")
    private Integer empno;

    @ExcelProperty(value = "員工名稱")
    private String ename;

    @ExcelProperty(value = "工作")
    private String job;

    @ExcelProperty(value = "主管編號")
    private Integer mgr;

    @ExcelProperty(value = "入職日期")
    private Date hiredate;

    @ExcelProperty(value = "薪資")
    private BigDecimal sal;

    @ExcelProperty(value = "獎金")
    private BigDecimal comm;

    @ExcelProperty(value = "所屬部門")
    private Integer deptno;

}

@Resource
private EmpService empService;
/**
 * 分批次導(dǎo)出
 */
@GetMapping("/export")
public void export() throws IOException {
    StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    empService.export();
    stopWatch.stop();
    System.out.println("共計(jì)耗時： " + stopWatch.getTotalTimeSeconds()+"S");
}

public class ExcelConstants {
    //一個sheet裝100w數(shù)據(jù)
    public static final Integer PER_SHEET_ROW_COUNT = 1000000;
    //每次查詢20w數(shù)據(jù)，每次寫入20w數(shù)據(jù)
    public static final Integer PER_WRITE_ROW_COUNT = 200000;
}

@Override
public void export() throws IOException {
    OutputStream outputStream =null;
    try {
        //記錄總數(shù):實(shí)際中需要根據(jù)查詢條件進(jìn)行統(tǒng)計(jì)即可
        //LambdaQueryWrapper<Emp> lambdaQueryWrapper = new QueryWrapper<Emp>().lambda().eq(Emp::getEmpno, 1000001);
        Integer totalCount = empMapper.selectCount(null);
        //每一個Sheet存放100w條數(shù)據(jù)
        Integer sheetDataRows = ExcelConstants.PER_SHEET_ROW_COUNT;
        //每次寫入的數(shù)據(jù)量20w,每頁查詢20W
        Integer writeDataRows = ExcelConstants.PER_WRITE_ROW_COUNT;
        //計(jì)算需要的Sheet數(shù)量
        Integer sheetNum = totalCount % sheetDataRows == 0 ? (totalCount / sheetDataRows) : (totalCount / sheetDataRows + 1);
        //計(jì)算一般情況下每一個Sheet需要寫入的次數(shù)(一般情況不包含最后一個sheet,因?yàn)樽詈笠粋€sheet不確定會寫入多少條數(shù)據(jù))
        Integer oneSheetWriteCount = sheetDataRows / writeDataRows;
        //計(jì)算最后一個sheet需要寫入的次數(shù)
        Integer lastSheetWriteCount = totalCount % sheetDataRows == 0 ? oneSheetWriteCount : (totalCount % sheetDataRows % writeDataRows == 0 ? (totalCount / sheetDataRows / writeDataRows) : (totalCount / sheetDataRows / writeDataRows + 1));

        ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletResponse response = requestAttributes.getResponse();
        outputStream = response.getOutputStream();
        //必須放到循環(huán)外，否則會刷新流
        ExcelWriter excelWriter = EasyExcel.write(outputStream).build();

        //開始分批查詢分次寫入
        for (int i = 0; i < sheetNum; i++) {
            //創(chuàng)建Sheet
            WriteSheet sheet = new WriteSheet();
            sheet.setSheetName("測試Sheet1"+i);
            sheet.setSheetNo(i);
            //循環(huán)寫入次數(shù): j的自增條件是當(dāng)不是最后一個Sheet的時候?qū)懭氪螖?shù)為正常的每個Sheet寫入的次數(shù),如果是最后一個就需要使用計(jì)算的次數(shù)lastSheetWriteCount
            for (int j = 0; j < (i != sheetNum - 1 ? oneSheetWriteCount : lastSheetWriteCount); j++) {
                //分頁查詢一次20w
                Page<Emp> page = empMapper.selectPage(new Page(j + 1 + oneSheetWriteCount * i, writeDataRows), null);
                List<Emp> empList = page.getRecords();
                List<EmpVo> empVoList = new ArrayList<>();
                for (Emp emp : empList) {
                    EmpVo empVo = new EmpVo();
                    BeanUtils.copyProperties(emp, empVo);
                    empVoList.add(empVo);
                }
                WriteSheet writeSheet = EasyExcel.writerSheet(i, "員工信息" + (i + 1)).head(EmpVo.class)
                        .registerWriteHandler(new LongestMatchColumnWidthStyleStrategy()).build();
                //寫數(shù)據(jù)
                excelWriter.write(empVoList, writeSheet);
            }
        }
        // 下載EXCEL
        response.setContentType("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
        response.setCharacterEncoding("utf-8");
        // 這里URLEncoder.encode可以防止瀏覽器端導(dǎo)出excel文件名中文亂碼 當(dāng)然和easyexcel沒有關(guān)系
        String fileName = URLEncoder.encode("員工信息", "UTF-8").replaceAll("\\+", "%20");
        response.setHeader("Content-disposition", "attachment;filename*=utf-8''" + fileName + ".xlsx");
        excelWriter.finish();
        outputStream.flush();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (BeansException e) {
        e.printStackTrace();
    }finally {
        if (outputStream != null) {
            outputStream.close();
        }
    }
}

@Resource
private EmpService empService;

@GetMapping("/importData")
public void importData() {
    String fileName = "C:\\Users\\asus\\Desktop\\員工信息.xlsx";
    //記錄開始讀取Excel時間,也是導(dǎo)入程序開始時間
    long startReadTime = System.currentTimeMillis();
    System.out.println("------開始讀取Excel的Sheet時間(包括導(dǎo)入數(shù)據(jù)過程):" + startReadTime + "ms------");
    //讀取所有Sheet的數(shù)據(jù).每次讀完一個Sheet就會調(diào)用這個方法
    EasyExcel.read(fileName, new EasyExceGeneralDatalListener(empService)).doReadAll();
    long endReadTime = System.currentTimeMillis();
    System.out.println("------結(jié)束讀取Excel的Sheet時間(包括導(dǎo)入數(shù)據(jù)過程):" + endReadTime + "ms------");
    System.out.println("------讀取Excel的Sheet時間(包括導(dǎo)入數(shù)據(jù))共計(jì)耗時:" + (endReadTime-startReadTime) + "ms------");
}

// 事件監(jiān)聽
public class EasyExceGeneralDatalListener extends AnalysisEventListener<Map<Integer, String>> {
    /**
     * 處理業(yè)務(wù)邏輯的Service,也可以是Mapper
     */
    private EmpService empService;

    /**
     * 用于存儲讀取的數(shù)據(jù)
     */
    private List<Map<Integer, String>> dataList = new ArrayList<Map<Integer, String>>();

    public EasyExceGeneralDatalListener() {
    }

    public EasyExceGeneralDatalListener(EmpService empService) {
        this.empService = empService;
    }

    @Override
    public void invoke(Map<Integer, String> data, AnalysisContext context) {
        //數(shù)據(jù)add進(jìn)入集合
        dataList.add(data);
        //size是否為100000條:這里其實(shí)就是分批.當(dāng)數(shù)據(jù)等于10w的時候執(zhí)行一次插入
        if (dataList.size() >= ExcelConstants.GENERAL_ONCE_SAVE_TO_DB_ROWS) {
            //存入數(shù)據(jù)庫:數(shù)據(jù)小于1w條使用Mybatis的批量插入即可;
            saveData();
            //清理集合便于GC回收
            dataList.clear();
        }
    }

    /**
     * 保存數(shù)據(jù)到DB
     *
     * @param
     * @MethodName: saveData
     * @return: void
     */
    private void saveData() {
        empService.importData(dataList);
        dataList.clear();
    }

    /**
     * Excel中所有數(shù)據(jù)解析完畢會調(diào)用此方法
     *
     * @param: context
     * @MethodName: doAfterAllAnalysed
     * @return: void
     */
    @Override
    public void doAfterAllAnalysed(AnalysisContext context) {
        saveData();
        dataList.clear();
    }
}

public interface EmpService {
    void export() throws IOException;

    void importData(List<Map<Integer, String>> dataList);

}

    /*
     * 測試用Excel導(dǎo)入超過10w條數(shù)據(jù),經(jīng)過測試發(fā)現(xiàn),使用Mybatis的批量插入速度非常慢,所以這里可以使用 數(shù)據(jù)分批+JDBC分批插入+事務(wù)來繼續(xù)插入速度會非?？?
    */
    @Override
    public void importData(List<Map<Integer, String>> dataList) {
        //結(jié)果集中數(shù)據(jù)為0時,結(jié)束方法.進(jìn)行下一次調(diào)用
        if (dataList.size() == 0) {
            return;
        }
        //JDBC分批插入+事務(wù)操作完成對20w數(shù)據(jù)的插入
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            long startTime = System.currentTimeMillis();
            System.out.println(dataList.size() + "條,開始導(dǎo)入到數(shù)據(jù)庫時間:" + startTime + "ms");
            conn = JDBCDruidUtils.getConnection();
            //控制事務(wù):默認(rèn)不提交
            conn.setAutoCommit(false);
            String sql = "insert into emp (`empno`, `ename`, `job`, `mgr`, `hiredate`, `sal`, `comm`, `deptno`) values";
            sql += "(?,?,?,?,?,?,?,?)";
            ps = conn.prepareStatement(sql);
            //循環(huán)結(jié)果集:這里循環(huán)不支持lambda表達(dá)式
            for (int i = 0; i < dataList.size(); i++) {
                Map<Integer, String> item = dataList.get(i);
                ps.setString(1, item.get(0));
                ps.setString(2, item.get(1));
                ps.setString(3, item.get(2));
                ps.setString(4, item.get(3));
                ps.setString(5, item.get(4));
                ps.setString(6, item.get(5));
                ps.setString(7, item.get(6));
                ps.setString(8, item.get(7));
                //將一組參數(shù)添加到此 PreparedStatement 對象的批處理命令中。
                ps.addBatch();
            }
            //執(zhí)行批處理
            ps.executeBatch();
            //手動提交事務(wù)
            conn.commit();
            long endTime = System.currentTimeMillis();
            System.out.println(dataList.size() + "條,結(jié)束導(dǎo)入到數(shù)據(jù)庫時間:" + endTime + "ms");
            System.out.println(dataList.size() + "條,導(dǎo)入用時:" + (endTime - startTime) + "ms");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            //關(guān)連接
            JDBCDruidUtils.close(conn, ps);
        }
    }

???????}

//JDBC工具類
public class JDBCDruidUtils {
    private static DataSource dataSource;

    /*
   創(chuàng)建數(shù)據(jù)Properties集合對象加載加載配置文件
    */
    static {
        Properties pro = new Properties();
        //加載數(shù)據(jù)庫連接池對象
        try {
            //獲取數(shù)據(jù)庫連接池對象
            pro.load(JDBCDruidUtils.class.getClassLoader().getResourceAsStream("druid.properties"));
            dataSource = DruidDataSourceFactory.createDataSource(pro);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /*
    獲取連接
     */
    public static Connection getConnection() throws SQLException {
        return dataSource.getConnection();
    }


    /**
     * 關(guān)閉conn,和 statement獨(dú)對象資源
     *
     * @param connection
     * @param statement
     * @MethodName: close
     * @return: void
     */
    public static void close(Connection connection, Statement statement) {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 關(guān)閉 conn , statement 和resultset三個對象資源
     *
     * @param connection
     * @param statement
     * @param resultSet
     * @MethodName: close
     * @return: void
     */
    public static void close(Connection connection, Statement statement, ResultSet resultSet) {
        close(connection, statement);
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /*
    獲取連接池對象
     */
    public static DataSource getDataSource() {
        return dataSource;
    }

}

# druid.properties配置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/llp?autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=GMT%2B8&allowMultiQueries=true&rewriteBatchedStatements=true
username=root
password=root
initialSize=10
maxActive=50
maxWait=60000