java导出excel浏览器下载，单线程VS多线程

java导出excel浏览器下载，单线程VS多线程

package com.mengyang.transactional.other.excelxssf;

import com.mengyang.transactional.other.myselfExcel.ExcelUtils;
import com.mengyang.transactional.pojo.ZhongXinDTO;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;

import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Field;
import java.net.URLEncoder;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CountDownLatch;

public class ExportExcelUtil {

Class<T> clazz;public ExportExcelUtil(Class<T> clazz) {this.clazz = clazz;
}//单线程
public void exportExcel(HttpServletResponse response, String excelHeaer, int sheetNum, List<T> dataList) {SXSSFWorkbook workbook = new SXSSFWorkbook(-1);String fileName = "中信报表导出" + ".xlsx";try {//使用workbook对象创建样式对象CellStyle cellStyle = workbook.createCellStyle();//创建字体对象Font font = workbook.createFont();//处理表格头部信息String[] head = excelHeaer.split(",");// 得到目标目标类的所有的字段列表Field[] fields = clazz.getDeclaredFields();for (Field field : fields) {field.setAccessible(true);}Sheet sheet = workbook.createSheet("XXX");ExcelUtils.setCellStyle(sheet, cellStyle, font);//遍历集合中的数据Iterator<T> iterator = dataList.iterator();int currentRow = 0;//写入头信息Row row = sheet.createRow(currentRow);for (int i = 0; i < head.length; i++) {Cell cell = row.createCell(i);cell.setCellValue(head[i]);cell.setCellStyle(cellStyle);}currentRow++;//写入业务数据while (iterator.hasNext()) {T t = iterator.next();row = sheet.createRow(currentRow);for (int i = 0; i < fields.length; i++) {Cell cell = row.createCell(i);cell.setCellValue(String.valueOf(fields[i].get(t)));cell.setCellStyle(cellStyle);}currentRow++;}//下载response.reset();response.setContentType("application/octet-stream; charset=utf-8");//以流的形式对文件进行下载response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fileName, "UTF-8"));//对文件名编码,防止文件名乱码workbook.write(response.getOutputStream());} catch (Exception e) {e.printStackTrace();} finally {//删除之前保存的临时文件workbook.dispose();}
}public void exportExcelAndMoreThread(HttpServletResponse response, String excelHeaer, int sheetNum, List<T> dataList) {SXSSFWorkbook workbook = new SXSSFWorkbook(-1);String fileName = "中信报表导出" + ".xlsx";try {//使用workbook对象创建样式对象CellStyle cellStyle = workbook.createCellStyle();//创建字体对象Font font = workbook.createFont();//处理表格头部信息String[] head = excelHeaer.split(",");CountDownLatch countDownLatch = new CountDownLatch(sheetNum);//倒计时开关// 得到目标目标类的所有的字段列表Field[] fields = clazz.getDeclaredFields();for (Field field : fields) {field.setAccessible(true);}//遍历集合中的数据//Iterator<T> iterator = dataList.iterator();int currentRow = 0;if (Objects.equals(0, sheetNum)) {//单线程处理Sheet sheet = workbook.createSheet("XXX");ExcelUtils.setCellStyle(sheet, cellStyle, font);//遍历集合中的数据Iterator<T> iterator = dataList.iterator();//写入头信息Row row = sheet.createRow(currentRow);for (int i = 0; i < head.length; i++) {Cell cell = row.createCell(i);cell.setCellValue(head[i]);cell.setCellStyle(cellStyle);}currentRow++;//写入业务数据while (iterator.hasNext()) {T t = iterator.next();row = sheet.createRow(currentRow);for (int i = 0; i < fields.length; i++) {Cell cell = row.createCell(i);cell.setCellValue(String.valueOf(fields[i].get(t)));cell.setCellStyle(cellStyle);}currentRow++;}} else {int dataCount = dataList.size();//数据的长度//如何把list集合分成对应的份数，开几条线程就相当于把数据分成几份int avgNum = (int) Math.floor(dataCount / sheetNum);//获得平均值int remainder = dataCount % sheetNum;//最后有余数  102%4 =2int fromIndex = 0;int toIndex = 0;for (int i = 0; i < sheetNum; i++) {fromIndex = i * avgNum;if (i == sheetNum - 1) {//最后一个线程被开启toIndex = (i + 1) * avgNum - 1 + remainder;} else {toIndex = (i + 1) * avgNum - 1;}//分解数据List<T> data = dataList.subList(fromIndex, toIndex + 1);Sheet sheet1 = workbook.createSheet("项目数据" + i);ExcelUtils.setCellStyle(sheet1, cellStyle, font);new Thread(() -> {Iterator<T> iterator = data.iterator();int startIndex = 0;Row row = sheet1.createRow(startIndex);for (int j = 0; j < head.length; j++) {Cell cell = row.createCell(j);cell.setCellValue(head[j]);cell.setCellStyle(cellStyle);}startIndex++;while (iterator.hasNext()) {T t = iterator.next();row = sheet1.createRow(startIndex);for (int k = 0; k < fields.length; k++) {Cell cell = row.createCell(k);try {cell.setCellValue(String.valueOf(fields[k].get(t)));cell.setCellStyle(cellStyle);} catch (IllegalAccessException e) {e.printStackTrace();}}startIndex++;}countDownLatch.countDown();}, "线程" + i).start();}//告诉主线程，要等所有的线程运行完再进行Excel的导出countDownLatch.await();}//下载response.reset();response.setContentType("application/octet-stream; charset=utf-8");//以流的形式对文件进行下载response.setHeader("Content-Disposition", "attachment; filename=" + URLEncoder.encode(fileName, "UTF-8"));//对文件名编码,防止文件名乱码workbook.write(response.getOutputStream());} catch (Exception e) {e.printStackTrace();} finally {//删除之前保存的临时文件workbook.dispose();}
}

}