本文主要是介绍Java实现Excel百万级数据的导入(约30s完成)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
前言
在遇到大数据量excel，50MB大小或数百万级别的数据读取时，使用常用的POI容易导致读取时内存溢出或者cpu飙升。
本文讨论的是针对xlsx格式的excel文件上传，采用com.monitorjbl.xlsx.StreamingReader 。什么是StreamReader?
StreamReader 是 java.io 包中的一个类，用于读取字符流的高级类。它继承自 Reader 类，可以以字符为单位读取文件中的数据。
StreamReader的主要功能？
- 以字符为单位读取文件中的数据
- 提供了多种读取方法，如read()、readLine()等
- 可以指定字符编码，以适应不同类型的文件
StreamReader的优势？
- 简化了文件读取的过程，提供了高层次的读取方法可以处理不同类型的文件，如文本文件、CSV文件等
- 可以读取大型文件，节省内存空间
注：StreamReader只能用遍历形式读取数据
Sheet sheet = wk.getSheetAt(0);//遍历所有的行for (Row row : sheet) {System.out.println("开始遍历第" + row.getRowNum() + "行数据：");//遍历所有的列for (Cell cell : row) {System.out.print(cell.getStringCellValue() + " ");}System.out.println(" ");}
案例步骤
1、导入文件前端接口
Controller.java
/*** 导入文件前端接口*/@PostMapping("/importData")@ResponseBodypublic AjaxResult importData(MultipartFile file, boolean updateSupport) throws Exception {// 开始时间Long begin = new Date().getTime();// excel转换为List集合（约30s~40s）List<TpInstallationMaintenanceLabelDetailed> tpInstallationMaintenanceLabelDetailedList = largeFilesUtils.importExcelLargeFile(file, updateSupport);// 结束时间Long end = new Date().getTime();// 数据导入（约30s）String message = importInstallationMaintenanceLabelDetailed(tpInstallationMaintenanceLabelDetailedList, updateSupport);// 总用时(约60s~70s)message = message +"<br/>数据转换花费时间 : "+(end - begin) / 1000 + " s" ;// 返回return AjaxResult.success(message);}2、Excel数据转为List
largeFilesUtils.java
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;import com.monitorjbl.xlsx.StreamingReader;
import com.ruoyi.huawei.domain.TpInstallationMaintenanceLabelDetailed;/*** 大文件Excel导入* * @author y* @date 2024-03-29*/
@Service
public class LargeFilesUtils {/*** 大文件Excel导入* * @param* @return 工具*/public List<TpInstallationMaintenanceLabelDetailed> importExcelLargeFile(MultipartFile file,boolean updateSupport) {List<TpInstallationMaintenanceLabelDetailed> tpInstallationMaintenanceLabelDetailedList = new ArrayList<TpInstallationMaintenanceLabelDetailed>();try {// 大文件测试开始InputStream inputStream = file.getInputStream();// com.monitorjbl.xlsx.StreamingReader Workbook workbook = StreamingReader.builder().rowCacheSize(1000) // 缓存到内存中的行数(默认是10).bufferSize(10240) // 读取资源时，缓存到内存的字节大小(默认是1024).open(inputStream);// 获取第一个ShhetSheet sheet = workbook.getSheetAt(0);//boolean fastRowBoolean = true;// monitorjbl只能支持遍历，不能通过指定下标获取for (Row row : sheet) {// 判断是否首行if(fastRowBoolean) {// 设置为非首行fastRowBoolean = false;// continue 语句用于跳过当前循环中剩余的代码，并开始下一次迭代。continue;}// 创建实体TpInstallationMaintenanceLabelDetailed rowData = new TpInstallationMaintenanceLabelDetailed();// 列下标初始化int n = 0;// 遍历列for (Cell cell : row) {//switch (n) {// 第一列case 0:rowData.setPppoeAccount(cell.getStringCellValue());break;// 第二列case 1:rowData.setInstallationMaintenanceName(cell.getStringCellValue());break;case 2:rowData.setCounty(cell.getStringCellValue());break;case 3:rowData.setPoorQualityUser(cell.getStringCellValue());break;case 4:rowData.setOldLightCat(cell.getStringCellValue());break;case 5:rowData.setSetTopBoxWirelessConnection(cell.getStringCellValue());break;case 6:rowData.setPleaseUseXgponOnu(cell.getStringCellValue());break;case 7:rowData.setHighTemperatureLightCat(cell.getStringCellValue());break;case 8:rowData.setAnOldSetTopBox(cell.getStringCellValue());break;case 9:rowData.setTwoOldSetTopBoxes(cell.getStringCellValue());break;case 10:rowData.setThreeOldSetTopBoxes(cell.getStringCellValue());break;case 11:rowData.setAnPoorQualityRouter(cell.getStringCellValue());break;case 12:rowData.setTwoPoorQualityRouters(cell.getStringCellValue());break;case 13:rowData.setThreePoorQualityRouters(cell.getStringCellValue());break;case 14:rowData.setThreeOrMoreLowQualityRouters(cell.getStringCellValue());break;case 15:rowData.setThreeOrMoreOldSetTopBoxes(cell.getStringCellValue());break;case 16:rowData.setSeverelyPoorQualityUsersAndOldOpticalCats(cell.getStringCellValue());break;// 处理其他属性default:break;}// 列下标+1n = n+1;}tpInstallationMaintenanceLabelDetailedList.add(rowData);}workbook.close();} catch (Exception e) {// TODO: handle exceptionSystem.out.println(e);}return tpInstallationMaintenanceLabelDetailedList;}}
3、List集合数据导入
importInstallationMaintenanceLabelDetailed
/*** 导入文件分析*/public String importInstallationMaintenanceLabelDetailed(List<TpInstallationMaintenanceLabelDetailed> tpInstallationMaintenanceLabelDetailedList, Boolean isUpdateSupport){if (StringUtils.isNull(tpInstallationMaintenanceLabelDetailedList) || tpInstallationMaintenanceLabelDetailedList.size() == 0){throw new ServiceException("导入数据不能为空！");}// 执行开始时间Long begin = new Date().getTime();// 线程数final int THREAD_COUNT = 10;// 每个线程处理的数据量final int BATCH_SIZE = tpInstallationMaintenanceLabelDetailedList.size() / THREAD_COUNT;// ExecutorService是Java中对线程池定义的一个接口ExecutorService executor = Executors.newFixedThreadPool(THREAD_COUNT);// for (int i = 0; i < THREAD_COUNT; i++) {// List数据开始下标final int startIndex = i * BATCH_SIZE;// List数据结束下标final int endIndex = (i + 1) * BATCH_SIZE;// 线程池执行executor.submit(new Runnable() {public void run() {// 初始化数据库连接对象Connection conn = null;// 初始化预编译的 SQL 语句的对象PreparedStatement ps = null;try {// 获取连接conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/tool_platform_db?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8&useSSL=false", "root", "123456");//获取连接// 设置自动提交模式，默认trueconn.setAutoCommit(false);// sql前缀String prefix = "INSERT INTO tp_label_detailed ("+ "account,"+ "maintenance_name,"+ "county,quality_user,"+ "light_cat,wireless_connection,"+ "xgpon_onu,"+ "light_cat,"+ "an_box,two_boxes,"+ "three_boxes,"+ "an_router,"+ "two_routers,"+ "three_routers,"+ "three_or_more_routers,"+ "three_or_more_boxes,"+ "severely_and_cats"+ ") VALUES ";// 创建预编译对象ps = conn.prepareStatement(prefix);// 保存sql后缀StringBuffer suffix = new StringBuffer();// 执行条数int number_of_cycles = 0;//for (int j = startIndex; j < endIndex; j++) {// 拼接sqlsuffix.append("("+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getPppoeAccount()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getInstallationMaintenanceName()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getCounty()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getPoorQualityUser()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getOldLightCat()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getSetTopBoxWirelessConnection()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getPleaseUseXgponOnu()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getHighTemperatureLightCat()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getAnOldSetTopBox()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getTwoOldSetTopBoxes()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getThreeOldSetTopBoxes()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getAnPoorQualityRouter()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getTwoPoorQualityRouters()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getThreePoorQualityRouters()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getThreeOrMoreLowQualityRouters()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getThreeOrMoreOldSetTopBoxes()+"',"+"'"+tpInstallationMaintenanceLabelDetailedList.get(j).getSeverelyPoorQualityUsersAndOldOpticalCats()+"'"+"),"); //拼接sqlnumber_of_cycles = number_of_cycles +1;}// sql拼接String sql = prefix + suffix.substring(0, suffix.length() - 1);// 添加预处理sqlps.addBatch(sql);// 执行语句ps.executeBatch();// 提交conn.commit();// 初始化拼接sqlsuffix.setLength(0);// 初始化条数number_of_cycles = 1;} catch (SQLException e) {e.printStackTrace();} finally {if (ps != null) {try {// 关闭psps.close();} catch (SQLException e) {e.printStackTrace();}}if (conn != null) {try {// 关闭数据库连接conn.close();} catch (SQLException e) {e.printStackTrace();}}}}});}//关闭线程池,不接受新任务,但会把已添加的任务执行完executor.shutdown();// 等待所有线程完成任务while (!executor.isTerminated()) {} System.out.println("完成");// 结束时间Long end = new Date().getTime();// 耗时logger.debug(tpInstallationMaintenanceLabelDetailedList.size()+"条数据插入花费时间 : " + (end - begin) / 1000 + " s");//return "数据导入成功！共 " + tpInstallationMaintenanceLabelDetailedList.size() + " 条！"+"<br/>数据导入花费时间 : "+(end - begin) / 1000 + " s" ;}这篇关于Java实现Excel百万级数据的导入(约30s完成)的文章就介绍到这儿，希望我们推荐的文章对编程师们有所帮助！
