两种读写 Xls Or Xlsx 的方式：
1.方式一：
package com.ting.xls;
import com.google.common.collect.Maps;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
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.apache.poi.xssf.usermodel.XSSFWorkbook;
import java.io.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class XlsOrXlsxUtil {
public static void main(String[] args) throws Exception {
String filepath = "/ting/xls/Echo.xls";
String filepath2 = "/ting/xls/re5.xls";
// List list = readExcelWithTitle(filepath);
List list = readExcelWithoutTitle(filepath);
Map map = Maps.newHashMapWithExpectedSize(1);
map.put("re", list.get(0));
writeExcel(new FileOutputStream(new File(filepath2)), "xls", map);
}
//这应该是一个比较全的示例了，更加复杂的功能可以在此基础上扩展。此示例基于apache的POI类库，相关jar包就不列举了。这个类库很通用，网上很好找。
//1、不包含单元格合并的写excel
public static void writeExcel(OutputStream os, String excelExtName, Map data) throws IOException {
Workbook wb = null;
try {
if ("xls".equals(excelExtName)) {
wb = new HSSFWorkbook();
} else if ("xlsx".equals(excelExtName)) {
wb = new XSSFWorkbook();
} else {
throw new Exception("当前文件不是excel文件");
}
for (String sheetName : data.keySet()) {
Sheet sheet = wb.createSheet(sheetName);
List rowList = data.get(sheetName);
for (int i = 0; i < rowList.size(); i++) {
List cellList = (List) rowList.get(i);
Row row = sheet.createRow(i);
for (int j = 0; j < cellList.size(); j++) {
Cell cell = row.createCell(j);
cell.setCellValue((String) cellList.get(j));
}
}
}
wb.write(os);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (wb != null) {
wb.close();
}
}
}
//2、包含单元格合并的写excel 辅助vo
// class ExcelData {
// private String value;//单元格的值
//
// private int colSpan = 1;//单元格跨几列
//
// private int rowSpan = 1;//单元格跨几行
//
// private boolean alignCenter;//单元格是否居中，默认不居中，如果选择是，则水平和上下都居中
//
// public boolean isAlignCenter() {
// return alignCenter;
//
// }
//
// public void setAlignCenter(boolean alignCenter) {
// this.alignCenter = alignCenter;
//
// }
//
// public String getValue() {
// return value;
//
// }
//
// public void setValue(String value) {
// this.value = value;
//
// }
//
// public int getColSpan() {
// return colSpan;
//
// }
//
// public void setColSpan(int colSpan) {
// this.colSpan = colSpan;
//
// }
//
// public int getRowSpan() {
// return rowSpan;
//
// }
//
// public void setRowSpan(int rowSpan) {
// this.rowSpan = rowSpan;
//
// }
//
// }
//写excel文件的逻辑
// public static void testWrite(OutputStream os, String excelExtName, Map data) throws IOException {
// Workbook wb = null;
//
// CellStyle cellStyle = null;
//
// boolean isXls;
//
// try {
// if ("xls".equals(excelExtName)) {
// wb = new HSSFWorkbook();
//
// isXls = true;
//
// } else if ("xlsx".equals(excelExtName)) {
wb = new XSSFWorkbook();
//
// isXls = false;
//
// } else {
// throw new Exception("当前文件不是excel文件");
//
// }
//
// cellStyle = wb.createCellStyle();
//
// if (isXls) {
// cellStyle.setAlignment(HorizontalAlignment.CENTER);
//
// cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
//
// } else {
// cellStyle.setAlignment(HorizontalAlignment.CENTER);
//
// cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
//
// }
//
// for (String sheetName : data.keySet()) {
// Sheet sheet = wb.createSheet(sheetName);
//
// List rowList = (List) data.get(sheetName);
//
i 代表第几行 从0开始
//
// for (int i = 0; i < rowList.size(); i++) {
// List cellList = (List) rowList.get(i);
//
// Row row = sheet.createRow(i);
//
// int j = 0;//j 代表第几列 从0开始
//
// for (ExcelData exceldata: cellList) {
// if (excelData != null) {
// if (excelData.getColSpan() > 1 || excelData.getRowSpan() > 1) {
// CellRangeAddress cra = new CellRangeAddress(i, i + excelData.getRowSpan() - 1, j, j + excelData.getColSpan() - 1);
//
// sheet.addMergedRegion(cra);
//
// }
//
// Cell cell = row.createCell(j);
//
// cell.setCellValue(excelData.getValue());
//
// if (excelData.isAlignCenter()) {
// cell.setCellStyle(cellStyle);
//
// }
//
// j = j + excelData.getColSpan();
//
// } else {
// j++;
//
// }
//
// }
//
// }
//
// }
//
// wb.write(os);
//
// } catch (Exception e) {
// e.printStackTrace();
//
// } finally {
// if (wb != null) {
// wb.close();
//
// }
//
// }
//
// }
//测试代码
// public static void main(String[] args) throws IOException {
//
方式二：
package com.ting.xls;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import java.io.FileInputStream;
import java.io.FileOutputStream;
public class XlsOrXlsxWriteUtil {
public static void main(String[] args) throws Exception {
String filepath = "/ting/xls/Echo4.xls";
String filepath2 = "/ting/xls/Echo4.xls";
FileInputStream fs = new FileInputStream(filepath);
POIFSFileSystem ps = new POIFSFileSystem(fs);
HSSFWorkbook wb = new HSSFWorkbook(ps);
// HSSFSheet sheet=wb.getSheetAt(0);
// HSSFRow row=sheet.getRow(0);
// System.out.println(sheet.getLastRowNum()+" "+row.getLastCellNum());
FileOutputStream out = new FileOutputStream(filepath2);
// row=sheet.createRow((short)(sheet.getLastRowNum()+1));
// row.createCell(17).setCellValue(9.2);
// row.createCell(20).setCellValue(9);
int sheetSize = wb.getNumberOfSheets();
for (int i = 0; i < sheetSize; i++) {//遍历sheet页
Sheet sheet = wb.getSheetAt(i);
int rowSize = sheet.getLastRowNum() + 1;
for (int j = 0; j < rowSize; j++) {//遍历行
Row row = sheet.getRow(j);
if (row == null) {//略过空行
continue;
}
String u = null;
Cell cell = row.getCell(5);
int index = cell.getStringCellValue().indexOf("(LVEF");
if (index == -1) {
index = cell.getStringCellValue().indexOf("(EF");
}
if (index > 0) {
try {
int endIndex = cell.getStringCellValue().substring(index + 1, index + 20).indexOf(")");
u = cell.getStringCellValue().substring(index + 1, index + 20).substring(0, endIndex);
} catch (Exception e) {
u = cell.getStringCellValue().substring(index, index);
}
// System.out.printf(row.getCell(0).getStringCellValue());
System.out.println(u);
} else {
u = "正常";
// System.out.printf(row.getCell(0).getStringCellValue());
System.out.println(u);
}
int cellSize = row.getLastCellNum();//行中有多少个单元格，也就是有多少列
Cell add_cell = row.createCell(cellSize);
add_cell.setCellValue(u);
}
}
out.flush();
wb.write(out);
out.close();
// System.out.println(row.getPhysicalNumberOfCells()+" "+row.getLastCellNum());
}
}
参考：
POI中如何能对已经存在的Excel2007文件新加或修改内容？-CSDN论坛
Java写xlsx_java读写excel（POI，支持xls和xlsx两种格式）(示例代码)_飞翔的牛蛙君的博客-CSDN博客
