一. 简介
excel导出，如果数据量在百万级，会出现俩点内存溢出的问题：
1. 查询数据量过大，导致内存溢出。 该问题可以通过分批查询来解决；
2. 最后下载的时候大EXCEL转换的输出流内存溢出；该方式可以通过新版的SXSSFWorkbook来解决，可通过其构造函数执指定在内存中缓存的行数，剩余的会自动缓存在硬盘的临时目录上，同时，并不会存在页面卡顿的情况；
3. 为了能够使用不同的mapper并分批写数据, 采用了外观模式和模板方法模式，大体分三步：
a. 根据总数量生成excel，确定sheet的数量和写标题；
b. 写数据，在可变的匿名内部类中实现写入逻辑；
c. 转换输出流进行下载；
4. 使用案例在3.3 ServiceImpl中，可自行书写。
5. 最近太忙，写的太仓促，性能我感觉还有一倍的优化空间，比如循环次数，现在存在无意义空循环（这个耗时比较多）的情况，缓冲流，mybatis的浮标等，待优化........
6. 优化空间很大 刚试了下 把空循环去掉 4个字段 90W条数据 40s 180W 75s 300W 122s
哈哈 还未整理 TODO。
二. 工具代码
2.1 配置
2.1.1 pom.xml
<!-- poi -->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.17</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.17</version>
</dependency>注： 如果是springboot2.0,则不需要poi依赖，如果是1.0，则需要poi依赖，并且poi和poi-ooxml的版本要保持一致。
别的依赖我就不加了。
2.1.2 application.yml
# pagehelper
pagehelper:
helperDialect: mysql
reasonable: false # 如果没有数据 返回空 而非最后一页的数据
supportMethodsArguments: true
params: count=countSql
returnPageInfo: check注： reasonable一定要为false, 其他的我就不粘了。
2.2 ExcelConstant
package com.yzx.caasscs.constant;
/**
* @author qjwyss
* @date 2018/9/19
* @description EXCEL常量类
*/
public class ExcelConstant {
/**
* 每个sheet存储的记录数 100W
*/
public static final Integer PER_SHEET_ROW_COUNT = 1000000;
/**
* 每次向EXCEL写入的记录数(查询每页数据大小) 20W
*/
public static final Integer PER_WRITE_ROW_COUNT = 200000;
/**
* 每个sheet的写入次数 5
*/
public static final Integer PER_SHEET_WRITE_COUNT = PER_SHEET_ROW_COUNT / PER_WRITE_ROW_COUNT;
}
注： xlsx模式的excel每个sheet最多存储104W，此处我就每个sheet存储了 100W数据；每次查询20W数据； 自己根据内存来调合适的大小，写入次数待优化。
2.3 写数据委托类
package com.yzx.caasscs.util;
import org.apache.poi.xssf.streaming.SXSSFSheet;
/**
* @author qjwyss
* @date 2018/9/20
* @description EXCEL写数据委托类
*/
public interface WriteExcelDataDelegated {
/**
* EXCEL写数据委托类 针对不同的情况自行实现
*
* @param eachSheet 指定SHEET
* @param startRowCount 开始行
* @param endRowCount 结束行
* @param currentPage 分批查询开始页
* @param pageSize 分批查询数据量
* @throws Exception
*/
public abstract void writeExcelData(SXSSFSheet eachSheet, Integer startRowCount, Integer endRowCount, Integer currentPage, Integer pageSize) throws Exception;
}
2.4 DateUtil工具类（非必须）
package com.yzx.caasscs.util;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* @author qjwyss
* @date 2018/9/20
* @description 日期工具类
*/
public class DateUtil {
public static final String YYYY_MM_DD_HH_MM_SS = "yyyy-MM-dd HH:mm:ss";
/**
* 将日期转换为字符串
*
* @param date DATE日期
* @param format 转换格式
* @return 字符串日期
*/
public static String formatDate(Date date, String format) {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);
return simpleDateFormat.format(date);
}
}
2.5 POI工具类
package com.yzx.caasscs.util;
import com.yzx.caasscs.constant.ExcelConstant;
import org.apache.poi.xssf.streaming.SXSSFCell;
import org.apache.poi.xssf.streaming.SXSSFRow;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.http.HttpServletResponse;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Date;
/**
* @author qjwyss
* @date 2018/9/18
* @description POI导出工具类
*/
public class PoiUtil {
private final static Logger logger = LoggerFactory.getLogger(PoiUtil.class);
/**
* 初始化EXCEL(sheet个数和标题)
*
* @param totalRowCount 总记录数
* @param titles 标题集合
* @return XSSFWorkbook对象
*/
public static SXSSFWorkbook initExcel(Integer totalRowCount, String[] titles) {
// 在内存当中保持 100 行 , 超过的数据放到硬盘中在内存当中保持 100 行 , 超过的数据放到硬盘中
SXSSFWorkbook wb = new SXSSFWorkbook(100);
Integer sheetCount = ((totalRowCount % ExcelConstant.PER_SHEET_ROW_COUNT == 0) ?
(totalRowCount / ExcelConstant.PER_SHEET_ROW_COUNT) : (totalRowCount / ExcelConstant.PER_SHEET_ROW_COUNT + 1));
// 根据总记录数创建sheet并分配标题
for (int i = 0; i < sheetCount; i++) {
SXSSFSheet sheet = wb.createSheet("sheet" + (i + 1));
SXSSFRow headRow = sheet.createRow(0);
for (int j = 0; j < titles.length; j++) {
SXSSFCell headRowCell = headRow.createCell(j);
headRowCell.setCellValue(titles[j]);
}
}
return wb;
}
/**
* 下载EXCEL到本地指定的文件夹
*
* @param wb EXCEL对象SXSSFWorkbook
* @param exportPath 导出路径
*/
public static void downLoadExcelToLocalPath(SXSSFWorkbook wb, String exportPath) {
FileOutputStream fops = null;
try {
fops = new FileOutputStream(exportPath);
wb.write(fops);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != wb) {
try {
wb.dispose();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != fops) {
try {
fops.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
/**
* 下载EXCEL到浏览器
*
* @param wb EXCEL对象XSSFWorkbook
* @param response
* @param fileName 文件名称
* @throws IOException
*/
public static void downLoadExcelToWebsite(SXSSFWorkbook wb, HttpServletResponse response, String fileName) throws IOException {
response.setHeader("Content-disposition", "attachment; filename="
+ new String((fileName + ".xlsx").getBytes("utf-8"), "ISO8859-1"));//设置下载的文件名
OutputStream outputStream = null;
try {
outputStream = response.getOutputStream();
wb.write(outputStream);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != wb) {
try {
wb.dispose();
} catch (Exception e) {
e.printStackTrace();
}
}
if (null != outputStream) {
try {
outputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
/**
* 导出Excel到本地指定路径
*
* @param totalRowCount 总记录数
* @param titles 标题
* @param exportPath 导出路径
* @param writeExcelDataDelegated 向EXCEL写数据/处理格式的委托类 自行实现
* @throws Exception
*/
public static final void exportExcelToLocalPath(Integer totalRowCount, String[] titles, String exportPath, WriteExcelDataDelegated writeExcelDataDelegated) throws Exception {
logger.info("开始导出：" + DateUtil.formatDate(new Date(), DateUtil.YYYY_MM_DD_HH_MM_SS));
// 初始化EXCEL
SXSSFWorkbook wb = PoiUtil.initExcel(totalRowCount, titles);
// 调用委托类分批写数据
int sheetCount = wb.getNumberOfSheets();
for (int i = 0; i < sheetCount; i++) {
SXSSFSheet eachSheet = wb.getSheetAt(i);
for (int j = 1; j <= ExcelConstant.PER_SHEET_WRITE_COUNT; j++) {
int currentPage = i * ExcelConstant.PER_SHEET_WRITE_COUNT + j;
int pageSize = ExcelConstant.PER_WRITE_ROW_COUNT;
int startRowCount = (j - 1) * ExcelConstant.PER_WRITE_ROW_COUNT + 1;
int endRowCount = startRowCount + pageSize - 1;
writeExcelDataDelegated.writeExcelData(eachSheet, startRowCount, endRowCount, currentPage, pageSize);
}
}
// 下载EXCEL
PoiUtil.downLoadExcelToLocalPath(wb, exportPath);
logger.info("导出完成：" + DateUtil.formatDate(new Date(), DateUtil.YYYY_MM_DD_HH_MM_SS));
}
/**
* 导出Excel到浏览器
*
* @param response
* @param totalRowCount 总记录数
* @param fileName 文件名称
* @param titles 标题
* @param writeExcelDataDelegated 向EXCEL写数据/处理格式的委托类 自行实现
* @throws Exception
*/
public static final void exportExcelToWebsite(HttpServletResponse response, Integer totalRowCount, String fileName, String[] titles, WriteExcelDataDelegated writeExcelDataDelegated) throws Exception {
logger.info("开始导出：" + DateUtil.formatDate(new Date(), DateUtil.YYYY_MM_DD_HH_MM_SS));
// 初始化EXCEL
SXSSFWorkbook wb = PoiUtil.initExcel(totalRowCount, titles);
// 调用委托类分批写数据
int sheetCount = wb.getNumberOfSheets();
for (int i = 0; i < sheetCount; i++) {
SXSSFSheet eachSheet = wb.getSheetAt(i);
for (int j = 1; j <= ExcelConstant.PER_SHEET_WRITE_COUNT; j++) {
int currentPage = i * ExcelConstant.PER_SHEET_WRITE_COUNT + j;
int pageSize = ExcelConstant.PER_WRITE_ROW_COUNT;
int startRowCount = (j - 1) * ExcelConstant.PER_WRITE_ROW_COUNT + 1;
int endRowCount = startRowCount + pageSize - 1;
writeExcelDataDelegated.writeExcelData(eachSheet, startRowCount, endRowCount, currentPage, pageSize);
}
}
// 下载EXCEL
PoiUtil.downLoadExcelToWebsite(wb, response, fileName);
logger.info("导出完成：" + DateUtil.formatDate(new Date(), DateUtil.YYYY_MM_DD_HH_MM_SS));
}
}
三. 使用DEMO
3.1 Controller
package com.yzx.caasscs.controller.organiza;
import com.yzx.caasscs.controller.BaseController;
import com.yzx.caasscs.service.organiza.UserService;
import com.yzx.caasscs.vo.PageVO;
import com.yzx.caasscs.vo.ResultVO;
import com.yzx.caasscs.vo.organiza.UserVO;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiImplicitParam;
import io.swagger.annotations.ApiImplicitParams;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import springfox.documentation.annotations.ApiIgnore;
import javax.servlet.http.HttpServletResponse;
/**
* @author qjwyss
* @date 2018/8/30
* @description 用户控制类
*/
@Api(tags = {"UserController"}, description = "用户Controller")
@RestController
@RequestMapping(value = "/user")
public class UserController extends BaseController {
@Autowired
private UserService userService;
@ApiOperation("导出用户EXCEL")
@ApiImplicitParams({
@ApiImplicitParam(paramType = "query", dataType = "Long", name = "loginUid", value = "登录用户UID", required = true),
@ApiImplicitParam(paramType = "query", dataType = "Long", name = "uid", value = "用户UID", required = true)
})
@GetMapping("/export")
public ResultVO<Void> exportUser(@ApiIgnore UserVO userVO, HttpServletResponse response) throws Exception {
return this.userService.export(userVO, response);
}
}
3.2 Service
package com.yzx.caasscs.service.organiza;
import com.yzx.caasscs.vo.PageVO;
import com.yzx.caasscs.vo.ResultVO;
import com.yzx.caasscs.vo.organiza.UserVO;
import javax.servlet.http.HttpServletResponse;
/**
* @author qjwyss
* @date 2018/8/30
* @description 用户SERVICE
*/
public interface UserService {
/**
* 导出用户EXCEL
*
* @param userVO
* @return VOID
* @throws Exception
*/
ResultVO<Void> export(UserVO userVO, HttpServletResponse response) throws Exception;
}
3.3 ServiceImpl
package com.yzx.caasscs.service.impl.organiza;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.yzx.caasscs.constant.middleware.RedisConstant;
import com.yzx.caasscs.constant.organiza.UserApartmentConstant;
import com.yzx.caasscs.constant.organiza.UserConstant;
import com.yzx.caasscs.constant.organiza.UserRoleConstant;
import com.yzx.caasscs.constant.sys.SysLogConstant;
import com.yzx.caasscs.entity.dscaasscs.organiza.User;
import com.yzx.caasscs.entity.dscaasscs.organiza.UserApartment;
import com.yzx.caasscs.entity.dscaasscs.organiza.UserRole;
import com.yzx.caasscs.mapper.dscaasscs.organiza.UserApartmentMapper;
import com.yzx.caasscs.mapper.dscaasscs.organiza.UserMapper;
import com.yzx.caasscs.mapper.dscaasscs.organiza.UserRoleMapper;
import com.yzx.caasscs.mapper.dscaasscs.sys.RoleMenuMapper;
import com.yzx.caasscs.service.organiza.UserService;
import com.yzx.caasscs.service.sys.SysLogService;
import com.yzx.caasscs.util.CommonUtil;
import com.yzx.caasscs.util.DateUtil;
import com.yzx.caasscs.util.PoiUtil;
import com.yzx.caasscs.util.WriteExcelDataDelegated;
import com.yzx.caasscs.vo.PageVO;
import com.yzx.caasscs.vo.ResultVO;
import com.yzx.caasscs.vo.organiza.UserApartmentVO;
import com.yzx.caasscs.vo.organiza.UserRoleVO;
import com.yzx.caasscs.vo.organiza.UserVO;
import com.yzx.caasscs.vo.sys.MenuVO;
import com.yzx.caasscs.vo.sys.RoleMenuVO;
import com.yzx.caasscs.vo.sys.SysLogVO;
import net.sf.json.JSONObject;
import org.apache.poi.xssf.streaming.SXSSFRow;
import org.apache.poi.xssf.streaming.SXSSFSheet;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.CollectionUtils;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
/**
* @author qjwyss
* @date 2018/8/30
* @description 用户SERVICEIMPL
*/
@Service
public class UserServiceImpl implements UserService {
@Autowired
private UserMapper userMapper;
@Autowired
private HttpServletRequest request;
@Override
public ResultVO<Void> export(UserVO userVO, HttpServletResponse response) throws Exception {
// 总记录数
Integer totalRowCount = this.userMapper.selectUserVOCount(userVO);
// 导出EXCEL文件名称
String filaName = "用户EXCEL";
// 标题
String[] titles = {"账号", "密码", "状态", "昵称", "职位", "手机号", "邮箱", "创建人ID", "创建时间", "修改人ID", "修改时间"};
// 开始导入
PoiUtil.exportExcelToWebsite(response, totalRowCount, filaName, titles, new WriteExcelDataDelegated() {
@Override
public void writeExcelData(SXSSFSheet eachSheet, Integer startRowCount, Integer endRowCount, Integer currentPage, Integer pageSize) throws Exception {
PageHelper.startPage(currentPage, pageSize);
List<UserVO> userVOList = userMapper.selectUserVOList(userVO);
if (!CollectionUtils.isEmpty(userVOList)) {
// -------------- 这一块变量照着抄就行 强迫症 后期也封装起来 ----------------------
for (int i = startRowCount; i <= endRowCount; i++) {
SXSSFRow eachDataRow = eachSheet.createRow(i);
if ((i - startRowCount) < userVOList.size()) {
UserVO eachUserVO = userVOList.get(i - startRowCount);
// --------- 这一块变量照着抄就行 强迫症 后期也封装起来 -----------------------
eachDataRow.createCell(0).setCellValue(eachUserVO.getUsername() == null ? "" : eachUserVO.getUsername());
eachDataRow.createCell(1).setCellValue(eachUserVO.getPassword() == null ? "" : eachUserVO.getPassword());
eachDataRow.createCell(2).setCellValue(eachUserVO.getUserState() == null ? "" : (eachUserVO.getUserState() == 1 ? "启用" : "停用"));
eachDataRow.createCell(3).setCellValue(eachUserVO.getNickname() == null ? "" : eachUserVO.getNickname());
eachDataRow.createCell(4).setCellValue(eachUserVO.getPosition() == null ? "" : eachUserVO.getPosition());
eachDataRow.createCell(5).setCellValue(eachUserVO.getMobile() == null ? "" : eachUserVO.getMobile());
eachDataRow.createCell(6).setCellValue(eachUserVO.getEmail() == null ? "" : eachUserVO.getEmail());
if (null != eachUserVO.getCreateUid()) {
eachDataRow.createCell(7).setCellValue(eachUserVO.getCreateUid());
}
if (null != eachUserVO.getCreateTime()) {
eachDataRow.createCell(8).setCellValue(DateUtil.formatDate(eachUserVO.getCreateTime(), DateUtil.YYYY_MM_DD_HH_MM_SS));
}
if (null != eachUserVO.getUpdateUid()) {
eachDataRow.createCell(9).setCellValue(eachUserVO.getUpdateUid());
}
if (null != eachUserVO.getUpdateTime()) {
eachDataRow.createCell(10).setCellValue(DateUtil.formatDate(eachUserVO.getUpdateTime(), DateUtil.YYYY_MM_DD_HH_MM_SS));
}
}
}
}
}
});
return ResultVO.getSuccess("导出用户EXCEL成功");
}
}
3.4 mapper
package com.yzx.caasscs.mapper.dscaasscs.organiza;
import com.yzx.caasscs.entity.dscaasscs.organiza.User;
import com.yzx.caasscs.vo.organiza.UserVO;
import java.util.List;
/**
* @author qjwyss
* @date 2018/8/29
* @description 用户MAPPER
*/
public interface UserMapper {
/**
* 查询用户列表
*
* @param userVO
* @return UserVO集合
* @throws Exception
*/
List<UserVO> selectUserVOList(UserVO userVO) throws Exception;
/**
* 查询用户数量
*
* @param userVO
* @return 用户数量
* @throws Exception
*/
Integer selectUserVOCount(UserVO userVO) throws Exception;
}3.5 mapper.xml
<?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.yzx.caasscs.mapper.dscaasscs.organiza.UserMapper" >
<resultMap id="BaseResultMap" type="com.yzx.caasscs.entity.dscaasscs.organiza.User" >
<id column="uid" property="uid" jdbcType="BIGINT" />
<result column="username" property="username" jdbcType="VARCHAR" />
<result column="password" property="password" jdbcType="VARCHAR" />
<result column="state" property="state" jdbcType="INTEGER" />
<result column="nickname" property="nickname" jdbcType="VARCHAR" />
<result column="position" property="position" jdbcType="VARCHAR" />
<result column="mobile" property="mobile" jdbcType="VARCHAR" />
<result column="email" property="email" jdbcType="VARCHAR" />
<result column="create_uid" property="createUid" jdbcType="BIGINT" />
<result column="create_time" property="createTime" jdbcType="TIMESTAMP" />
<result column="update_uid" property="updateUid" jdbcType="BIGINT" />
<result column="update_time" property="updateTime" jdbcType="TIMESTAMP" />
</resultMap>
<!-- 查询用户分页列表返回MAP -->
<resultMap id="SelectUserVOListMap" type="com.yzx.caasscs.vo.organiza.UserVO">
<id column="uid" property="uid" jdbcType="BIGINT" />
<result column="username" property="username" jdbcType="VARCHAR" />
<result column="user_state" property="userState" jdbcType="INTEGER" />
<result column="nickname" property="nickname" jdbcType="VARCHAR" />
<result column="position" property="position" jdbcType="VARCHAR" />
<result column="mobile" property="mobile" jdbcType="VARCHAR" />
<result column="email" property="email" jdbcType="VARCHAR" />
<result column="create_uid" property="createUid" jdbcType="BIGINT" />
<result column="create_time" property="createTime" jdbcType="TIMESTAMP" />
<result column="update_uid" property="updateUid" jdbcType="BIGINT" />
<result column="update_time" property="updateTime" jdbcType="TIMESTAMP" />
<result column="apartment_name" property="apartmentName" jdbcType="VARCHAR" />
<result column="role_names" property="roleNames" jdbcType="VARCHAR" />
</resultMap>
<sql id="Base_Column_List" >
uid, username, password, state, nickname, position, mobile, email, create_uid, create_time,
update_uid, update_time
</sql>
<!-- 查询用户列表 -->
<select id="selectUserVOList" parameterType="com.yzx.caasscs.vo.organiza.UserVO" resultMap="SelectUserVOListMap">
SELECT
U.uid, U.username, U.state AS user_state, U.nickname, U.position, U.mobile, U.email, U.create_uid, U.create_time,
U.update_uid, U.update_time,
A.apartment_name,
(
SELECT
GROUP_CONCAT( R.role_name ) AS role_name_list
FROM
user_role AS UR
LEFT JOIN role AS R ON R.rid = UR.rid
WHERE
UR.state > 0
AND UR.uid = U.uid
GROUP BY UR.uid
) role_names
FROM
`user` AS U
LEFT JOIN user_apartment AS UA ON UA.uid = U.uid
LEFT JOIN apartment AS A ON A.aid = UA.aid
WHERE
U.state > 0
<if test="userState != null">
AND U.state = #{userState,jdbcType=INTEGER}
</if>
<if test="nickname != null and nickname != ''">
AND U.nickname LIKE CONCAT("%", #{nickname,jdbcType=VARCHAR}, "%")
</if>
<if test="apartmentName != null and apartmentName != ''">
AND A.apartment_name LIKE CONCAT("%", #{apartmentName,jdbcType=VARCHAR}, "%")
</if>
ORDER BY U.create_time DESC
</select>
<!-- 查询用户列表数量 -->
<select id="selectUserVOCount" parameterType="com.yzx.caasscs.vo.organiza.UserVO" resultType="java.lang.Integer" >
SELECT
COUNT(1)
FROM
`user` AS U
LEFT JOIN user_apartment AS UA ON UA.uid = U.uid
LEFT JOIN apartment AS A ON A.aid = UA.aid
WHERE
U.state > 0
<if test="userState != null">
AND U.state = #{userState,jdbcType=INTEGER}
</if>
<if test="nickname != null and nickname != ''">
AND U.nickname LIKE CONCAT("%", #{nickname,jdbcType=VARCHAR}, "%")
</if>
<if test="apartmentName != null and apartmentName != ''">
AND A.apartment_name LIKE CONCAT("%", #{apartmentName,jdbcType=VARCHAR}, "%")
</if>
</select>
</mapper>4. 测试
每个sheet存100W，每次查询写20W，每条记录10个字段，时间如下：
| 数据量 | 时间 |
| 100W | 3.5分钟 |
| 150W | 7分钟 |