Java实现导出excel表格功能，大部分都会使用apache poi，apache poi API 地址
POI之前的版本不支持大数据量处理，如果数据过多则经常报OOM错误，有时候调整JVM大小效果也不是太好。3.8版本的POI新出来了SXSSFWorkbook,可以支持大数据量的操作，只是SXSSFWorkbook只支持.xlsx格式，不支持.xls格式。
3.8版本的POI对excel的导出操作，一般只使用HSSFWorkbook以及SXSSFWorkbook，HSSFWorkbook用来处理较少的数据量，SXSSFWorkbook用来处理大数据量以及超大数据量的导出。
代码：
git地址 有3.9jar包
package qs.test;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;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.util.CellReference;import org.apache.poi.xssf.streaming.SXSSFWorkbook;/*** ClassName: SXSSFTest* @Description: TODO* @author qiaoshuai*/public class SXSSFTest {public static void main(String[] args) throws IOException {// 创建基于stream的工作薄对象的SXSSFWorkbook wb = new SXSSFWorkbook(100); // keep 100 rows in memory,// exceeding rows will be// flushed to disk// SXSSFWorkbook wb = new SXSSFWorkbook();// wb.setCompressTempFiles(true); // temp files will be gzippedSheet sh = wb.createSheet();// 使用createRow将信息写在内存中。for (int rownum = 0; rownum < 1000; rownum++) {Row row = sh.createRow(rownum);for (int cellnum = 0; cellnum < 10; cellnum++) {Cell cell = row.createCell(cellnum);String address = new CellReference(cell).formatAsString();cell.setCellValue(address);}}// Rows with rownum < 900 are flushed and not accessible// 当使用getRow方法访问的时候，将内存中的信息刷新到硬盘中去。for (int rownum = 0; rownum < 900; rownum++) {System.out.println(sh.getRow(rownum));}// ther last 100 rows are still in memoryfor (int rownum = 900; rownum < 1000; rownum++) {System.out.println(sh.getRow(rownum));}// 写入文件中FileOutputStream out = new FileOutputStream("G://sxssf.xlsx");wb.write(out);// 关闭文件流对象out.close();System.out.println("基于流写入执行完毕!");}}
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在此基础上再优化的方案是导出的Excel表格生成多个工作表即生成多个sheet。
代码：
import java.io.IOException;import java.io.UnsupportedEncodingException;import .URLEncoder;import java.util.ArrayList;import java.util.Date;import java.util.LinkedHashMap;import java.util.List;import org.springframework.http.HttpHeaders;import org.springframework.http.HttpStatus;import org.springframework.http.MediaType;import org.springframework.http.ResponseEntity;import mon.DateFormatUtil;public class ExlUtil2 {/*** @param excelHeader* 表头信息* @param list* 要导出到excel的数据源,List类型* @param sheetName* 表名* @return*/public static ResponseEntity<byte[]> getDataStream(ExcelHeader excelHeader,List list, String sheetName) {LinkedHashMap<String, List> map = new LinkedHashMap<String, List>();List<String[]> headNames = new ArrayList<String[]>();List<String[]> fieldNames = new ArrayList<String[]>();String[] sheetNames = new String[100];//处理Excel生成多个工作表 //定义为每个工作表数据为50000条if (list.size() > 50000) {int k = (list.size() + 50000) / 50000;for (int i = 1; i <= k; i++) {if (i < k) {map.put(sheetName + i,list.subList((i - 1) * 50000, i * 50000));} else {map.put(sheetName + i,list.subList((i - 1) * 50000, list.size()));}headNames.add(excelHeader.getHeadNames().get(0));fieldNames.add(excelHeader.getFieldNames().get(0));sheetNames[i - 1] = sheetName;}} else {map.put(sheetName, list);headNames.add(excelHeader.getHeadNames().get(0));fieldNames.add(excelHeader.getFieldNames().get(0));sheetNames[0] = sheetName;}byte[] buffer = null;try {buffer = ExcelUtil2.output(headNames, fieldNames, sheetNames, map);} catch (IllegalArgumentException | IllegalAccessException| IOException e) {e.printStackTrace();}HttpHeaders headers = new HttpHeaders();headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);/** try { sheetName=URLEncoder.encode(sheetName,"UTF8"); } catch* (UnsupportedEncodingException e) { e.printStackTrace(); }*/try {sheetName = new String(sheetName.getBytes("gbk"), "iso-8859-1");} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}String fileGenerateTime = DateFormatUtil.toStr(new Date());headers.setContentDispositionFormData("attachment", sheetName+ fileGenerateTime + ".xlsx");return new ResponseEntity<byte[]>(buffer, headers, HttpStatus.CREATED);};}
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代码
