引入jar包
首先，在maven中pom.xml添加
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.17</version>
</dependency>
要用XSSFWorkbook和SXSSHWorkbook（处理大量数据用）还需引入
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.17</version>
</dependency>
代码
新建Excel文件，并制定Excel版本，表单名称，表头，数据及Excel文件路径
/**
* 新建Excel文件，New Workbook
* @param excelType 可为null，Excel版本，可为2003（.xls）或者2007（.xlsx）,默认为2003版本
* @param sheetName 新建表单名称
* @param headList 表头List集合
* @param dataList 数据List<List<集合>>(行<列>)
* @param path 新建excel路径
* @return
*/
public static boolean createWorkBook(String excelType, String sheetName, List<String> headList,List<List<String>> dataList,String path){
Workbook wb = null;
/*创建文件*/
if (excelType == null || excelType.endsWith("2003")) {
/*操作Excel2003以前（包括2003）的版本，扩展名是.xls */
wb = new HSSFWorkbook();
}else if (excelType.endsWith("2007")){
/*XSSFWorkbook:是操作Excel2007的版本，扩展名是.xlsx */
wb = new XSSFWorkbook();
}else { //默认为2003版本
/*操作Excel2003以前（包括2003）的版本，扩展名是.xls */
wb = new HSSFWorkbook();
}
/*Excel文件创建完毕*/
CreationHelper createHelper = wb.getCreationHelper(); //创建帮助工具
/*创建表单*/
Sheet sheet = wb.createSheet(sheetName!=null?sheetName:"new sheet");
// Note that sheet name is Excel must not exceed 31 characters（注意sheet的名字的长度不能超过31个字符，若是超过的话，会自动截取前31个字符）
// and must not contain any of the any of the following characters:（不能包含下列字符）
// 0x0000 0x0003 colon (:) backslash (\) asterisk (*) question mark (?) forward slash (/) opening square bracket ([) closing square bracket (])
/*若是包含的话，会报错。但有一个解决此问题的方法，
就是调用WorkbookUtil的createSafeSheetName(String nameProposal)方法来创建sheet name,
若是有如上特殊字符，它会自动用空字符来替换掉，自动过滤。*/
/*String safeName = WorkbookUtil.createSafeSheetName("[O'Brien's sales*?]"); // returns " O'Brien's sales "过滤掉上面出现的不合法字符
Sheet sheet3 = workbook.createSheet(safeName); //然后就创建成功了*/
/*表单创建完毕*/
//设置字体
Font headFont = wb.createFont();
headFont.setFontHeightInPoints((short)14);
headFont.setFontName("Courier New");
headFont.setItalic(false);
headFont.setStrikeout(false);
//设置头部单元格样式
CellStyle headStyle = wb.createCellStyle();
headStyle.setBorderBottom(BorderStyle.THICK); //设置单元格线条
headStyle.setBottomBorderColor(IndexedColors.BLACK.getIndex()); //设置单元格颜色
headStyle.setBorderLeft(BorderStyle.THICK);
headStyle.setLeftBorderColor(IndexedColors.BLACK.getIndex());
headStyle.setBorderRight(BorderStyle.THICK);
headStyle.setRightBorderColor(IndexedColors.BLACK.getIndex());
headStyle.setBorderTop(BorderStyle.THICK);
headStyle.setTopBorderColor(IndexedColors.BLACK.getIndex());
headStyle.setAlignment(HorizontalAlignment.CENTER); //设置水平对齐方式
headStyle.setVerticalAlignment(VerticalAlignment.CENTER); //设置垂直对齐方式
//headStyle.setShrinkToFit(true); //自动伸缩
headStyle.setFont(headFont); //设置字体
/*设置数据单元格格式*/
CellStyle dataStyle = wb.createCellStyle();
dataStyle.setBorderBottom(BorderStyle.THIN); //设置单元格线条
dataStyle.setBottomBorderColor(IndexedColors.BLACK.getIndex()); //设置单元格颜色
dataStyle.setBorderLeft(BorderStyle.THIN);
dataStyle.setLeftBorderColor(IndexedColors.BLACK.getIndex());
dataStyle.setBorderRight(BorderStyle.THIN);
dataStyle.setRightBorderColor(IndexedColors.BLACK.getIndex());
dataStyle.setBorderTop(BorderStyle.THIN);
dataStyle.setTopBorderColor(IndexedColors.BLACK.getIndex());
dataStyle.setAlignment(HorizontalAlignment.LEFT); //设置水平对齐方式
dataStyle.setVerticalAlignment(VerticalAlignment.CENTER); //设置垂直对齐方式
//dataStyle.setShrinkToFit(true); //自动伸缩
/*创建行Rows及单元格Cells*/
Row headRow = sheet.createRow(0); //第一行为头
for (int i=0;i<headList.size();i++){ //遍历表头数据
Cell cell = headRow.createCell(i); //创建单元格
cell.setCellValue(createHelper.createRichTextString(headList.get(i))); //设置值
cell.setCellStyle(headStyle); //设置样式
}
int rowIndex = 1; //当前行索引
//创建Rows
for (List<String> rowdata : dataList){ //遍历所有数据
Row row = sheet.createRow(rowIndex++); //第一行为头
for (int j = 0;j< rowdata.size();j++){ //编译每一行
Cell cell = row.createCell(j);
cell.setCellStyle(dataStyle);
cell.setCellValue(createHelper.createRichTextString(rowdata.get(j)));
}
}
/*创建rows和cells完毕*/
/*设置列自动对齐*/
for (int i =0;i<headList.size();i++){
sheet.autoSizeColumn(i);
}
try (OutputStream fileOut = new FileOutputStream(path)) { //获取文件流
wb.write(fileOut); //将workbook写入文件流
} catch (FileNotFoundException e) {
e.printStackTrace();
return false;
} catch (IOException e) {
e.printStackTrace();
return false;
}
return true;
}
工具类其他方法
public static Workbook getWorkBook(String path) throws IOException, InvalidFormatException {
File file = new File(path); //目标Excel文件
File parent = new File(file.getParent()); //Excel的父文件夹
if (!parent.exists()){ //判断父文件夹是否存在
parent.mkdirs(); //建立父文件夹
}
Workbook wb = null;
if(file.exists()){ //如果文件存在
wb = WorkbookFactory.create(file); //打开文件
}else { //如果目标文件不存在
if (path.endsWith(".xls")) {
/*操作Excel2003以前（包括2003）的版本，扩展名是.xls */
wb = new HSSFWorkbook();
} else if (path.endsWith(".xlsx")) {
/*XSSFWorkbook:是操作Excel2007的版本，扩展名是.xlsx */
wb = new XSSFWorkbook();
} else {
new Exception(path + "后缀名错误!");
}
}
/*获取表单总数*/
int sheetCount = wb.getNumberOfSheets();
/*获取某一表单总行数*/
Sheet sheet = wb.createSheet();
//Sheet sheet = wb.getSheetAt(0);
System.out.println("表单数:"+sheetCount);
System.out.println("第一行索引:"+sheet.getFirstRowNum());
System.out.println("最后一行索引"+sheet.getLastRowNum());
int rowIndex = sheet.getLastRowNum()+1;
for (int i=0;i<=3;i++) {
Row row = sheet.createRow(rowIndex++);
for (int j = 0; j < 10; j++) {
Cell cell = row.createCell(j);
cell.setCellValue("格"+i + j);
}
}
try (OutputStream fileOut = new FileOutputStream(file)) { //获取文件流
fileOut.flush();
wb.write(fileOut); //将workbook写入文件流
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return wb;
}
//创建一个不存在的excel文件
private static Workbook createNewWorkbookIfNotExist(String fileName) throws Exception {
Workbook wb = null;
if(fileName.endsWith(".xls")) {
wb = new HSSFWorkbook();
} else if(fileName.endsWith(".xlsx")) {
wb = new XSSFWorkbook();
} else {
throw new Exception("文件类型错误！既不是.xls也不是.xlsx");
}
try{
OutputStream output = new FileOutputStream(fileName);
wb.write(output);
}catch(FileNotFoundException e) {
System.out.println("文件创建失败，失败原因为：" + e.getMessage());
throw new FileNotFoundException();
}
System.out.println(fileName + "文件创建成功！");
return wb;
}
//创建一个新的或者已存在的Excel文档的Workbook
public static Workbook createWorkbook(String fileName) throws Exception {
InputStream input = null;
Workbook wb = null;
try{
input = new FileInputStream(fileName);
wb = WorkbookFactory.create(input);
if (!new File(fileName).exists()){ //如果不存在
wb = createNewWorkbookIfNotExist(fileName); //创建新的
}
} catch(OldExcelFormatException e) {
System.out.println("文件打开失败，原因：要打开的Excel文件版本过低！");
throw new OldExcelFormatException("文件版本过低");
} finally {
if(input != null) {
input.close();
}
}
return wb;
}
//创建sheet
public static Sheet createSheet(Workbook wb , String sheetName) {
Sheet sheet = wb.getSheet(sheetName);
if(sheet == null) {
System.out.println("表单" + sheetName + "不存在，试图创建该sheet，请稍后……");
sheet = wb.createSheet(sheetName);
System.out.println("名为" + sheetName +"的sheet创建成功！");
}
return sheet;
}
//创建行row
public static Row createRow(Sheet sheet , int rowNum) {
Row row = sheet.getRow(rowNum);
if(row == null) {
System.out.println("行号为：" + rowNum + "的行不存在，正试图创建该行，请稍后……");
row = sheet.createRow(rowNum);
System.out.println("行号为：" + rowNum + "的行创建成功！");
}
return row;
}
//创建单元格cell
public static Cell createCell(Row row , int cellNum) {
Cell cell = row.getCell(cellNum);
if(cell == null) {
System.out.println("该单元格不存在，正在试图创建该单元格，请稍后……");
cell = row.createCell(cellNum);
System.out.println("该单元格创建成功！");
}
return cell;
}
/**
* 追加到已有excel
* @param dataList 数据
* @param name 文件名
*/
public static void addExcel(List<LinkedHashMap<String,Object>> dataList, String name) throws IOException {
FileInputStream fileInputStream=new FileInputStream("d://"+name+".xls"); //获取d://test.xls,建立数据的输入通道
POIFSFileSystem poifsFileSystem=new POIFSFileSystem(fileInputStream); //使用POI提供的方法得到excel的信息
HSSFWorkbook Workbook=new HSSFWorkbook(poifsFileSystem);//得到文档对象
HSSFSheet sheet=Workbook.getSheet(name); //根据name获取sheet表
HSSFCellStyle cellStyle = Workbook.createCellStyle();
/*cellStyle.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框
cellStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);//左边框
cellStyle.setBorderTop(HSSFCellStyle.BORDER_THIN);//上边框
cellStyle.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框
cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 居中*/
// HSSFRow row=sheet.getRow(0); //获取第一行
System.out.println("最后一行的行号 :"+sheet.getLastRowNum() + 1); //分别得到最后一行的行号，和第3条记录的最后一个单元格
//System.out.println("最后一个单元格 :"+row.getLastCellNum()); //分别得到最后一行的行号，和第3条记录的最后一个单元格
// HSSFRow startRow=sheet.createRow((short)(sheet.getLastRowNum()+1)); // 追加开始行
// -----------------追加数据-------------------
int start = sheet.getLastRowNum() + 1; //插入数据开始行
for (int i = 0; i < dataList.size(); i++){
HSSFRow startRow = sheet.createRow(i+start);
AtomicInteger j = new AtomicInteger();
LinkedHashMap<String ,Object> ltem = dataList.get(i);
}
// 输出Excel文件
FileOutputStream out=new FileOutputStream("d://"+name+".xls"); //向d://test.xls中写数据
out.flush();
Workbook.write(out);
out.close();
}
public static void readExcel(String name) throws IOException {
FileInputStream fileInputStream=new FileInputStream("d:\\"+name+".xls"); //获取d://test.xls,建立数据的输入通道
POIFSFileSystem poifsFileSystem=new POIFSFileSystem(fileInputStream); //使用POI提供的方法得到excel的信息
HSSFWorkbook Workbook=new HSSFWorkbook(poifsFileSystem);//得到文档对象
HSSFSheet sheet=Workbook.getSheet(name); //根据name获取sheet表
HSSFRow row=sheet.getRow(1); //获取第二行（第一行一般是标题）
int lastRow = sheet.getLastRowNum(); // 返回的是值从0开始的
System.out.println("总行数：" + (lastRow + 1));
int lastCell = row.getLastCellNum(); // 返回的值是从1开始的.....
System.out.println("总列数：" + lastCell);
for (int i = 0; i <= lastRow; i++){
row=sheet.getRow(i);
if (row != null){
for (int j = 0; j < lastCell; j++){
HSSFCell cell = row.getCell(j);
if (cell != null) System.out.println(cell.getStringCellValue());
}
}
}
}