利用POI生成带表头的Excel

1.关于Excel版本的一点了解

在项目工作中主要使用两个版本，03版文件名以“.xls”结尾,最大处理行数为65536，07版文件名以“.xlsx”结尾，最大处理行数为1048576。

2.关于Excel的相关概念

工作簿工作表行单元格

3.POI版本使用3.11，创建maven工程方便导入jar包

<!-- https://mvnrepository.com/artifact/org.apache.poi/poi --><dependency><groupId>org.apache.poi</groupId><artifactId>poi</artifactId><version>3.11</version></dependency><!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml --><dependency><groupId>org.apache.poi</groupId><artifactId>poi-ooxml</artifactId><version>3.11</version></dependency>

4.POI操作Excel工作簿的三个实现类(实现接口Workbook)

POI处理不同需求的Excel操作有不同的实现类，03版的xls对应HSSFWorkbook，07版的xlsx对应XSSFWorkbook，大数据量的写操作使用SXSSFWorkbook，大概的区别就是HSSFWorkbook读取的最大行数是65536，读写的速度相对较快，但存在弊端，不能写更多行的数据，这时候XSSFWorkbook登场，但是XSSFWorkbook采用一次性写出数据，如果数据量很大内存又不够，容易造成OOM异常，而SXSSFWorkbook使用了滑动窗口的概念，默认在内存中最多保留100行数据，超过100行的时候，就会把最小索引的行写入到临时文件中，这样就可以尽可能的避免出现OOM异常，大家根据实际需求选择相应的实现类。本次讲解使用HSSFWorkbook

5.HSSFWorkbook常用类与Excel对象的对应关系

HSSFWorkbook 工作簿对象
HSSFSheet 工作表对象
HSSFRow 行对象
HSSFCell 单元格对象
HSSFCellStyle 单元格样式对象
HSSFFont 字体对象

6.生成没有单元格边框的表头

在Excel里面默认的边框线是灰色的，生成没有边框线的单元格的逻辑就是想边框线的颜色改为白色,由于是演示代码，有些冗余代码没有提取出来，大家自行根据需求进行处理。

    public static void setSheetHead() {// 文件路径，03版的文件名以.xls结尾，07版的文件名以.xlsx结尾String filePath = "/Users/lavined/Desktop/test01.xls";FileOutputStream os = null;// 最大列数int cellNum = 10;int cellNumTemp = cellNum - 1;// 工作表名称String sheetName = "学生信息表";// 创建工作簿对象Workbook workbook = new HSSFWorkbook();// 创建工作表对象Sheet sheet = workbook.createSheet(sheetName);// 设置列宽sheet.setDefaultColumnWidth(13);// 设置单元格格式CellStyle cellStyle = workbook.createCellStyle();// 边框颜色白色cellStyle.setTopBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setLeftBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setRightBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setBottomBorderColor(IndexedColors.WHITE.getIndex());// 边框线型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// 由于采用无边框样式以后，最后一个单元格的右边框会消失，所以给最后一个单元格的下一个单元格设置样式CellStyle leftCellStyle = workbook.createCellStyle();leftCellStyle.setLeftBorderColor(IndexedColors.GREY_25_PERCENT.getIndex());leftCellStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);// 内容居中cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);cellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 设置字体Font font = workbook.createFont();font.setBold(true);// 粗体font.setFontHeightInPoints((short) 14);// 设置字体大小cellStyle.setFont(font);// 创建行对象Row row = sheet.createRow(0);for (int i = 0; i < cellNum; i++) {// 创建单元格对象Cell cell = row.createCell(i);if (i == 0) {cell.setCellValue(sheetName);}// 设置单元格样式cell.setCellStyle(cellStyle);}row.createCell(cellNum).setCellStyle(leftCellStyle);// 合并单元格CellRangeAddress region1 = new CellRangeAddress(0, 0, 0, cellNumTemp);sheet.addMergedRegion(region1);// 空一行sheet.createRow(1);CellRangeAddress region2 = new CellRangeAddress(1, 1, 0, cellNumTemp);sheet.addMergedRegion(region2);// 第二级表头Row sheetRow2 = sheet.createRow(2);int lastRemarkCellNum = cellNum - 3;for (int i = 0; i < cellNum; i++) {Cell cell = sheetRow2.createCell(i);if (i == 0) {cell.setCellValue("班级：三年级一班");}if (i == 3) {cell.setCellValue("人数：10人");}if (i == lastRemarkCellNum) {cell.setCellValue("创建时间：2021-03-01 17:09:47");}// 设置单元格样式cell.setCellStyle(cellStyle);}sheetRow2.createCell(cellNum).setCellStyle(leftCellStyle);// 合并单元格CellRangeAddress region3 = new CellRangeAddress(2, 2, 0, 2);sheet.addMergedRegion(region3);CellRangeAddress region4 = new CellRangeAddress(2, 2, 3, lastRemarkCellNum -1);sheet.addMergedRegion(region4);CellRangeAddress region5 = new CellRangeAddress(2, 2, lastRemarkCellNum, cellNumTemp);sheet.addMergedRegion(region5);sheet.createRow(3);CellRangeAddress region6 = new CellRangeAddress(3, 3, 0, cellNumTemp);sheet.addMergedRegion(region6);// 以流的方式写出文件try {os = new FileOutputStream(filePath);workbook.write(os);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {if (os != null) {try {os.close();} catch (IOException e) {e.printStackTrace();}}}}

代码结果如下：

7.生成带背景色的数据表头

public static void setDataHead(){String filePath = "/Users/lavined/Desktop/test01.xls";FileOutputStream os = null;// 工作表名称String sheetName = "学生信息表";// 创建工作簿对象Workbook workbook = new HSSFWorkbook();// 创建工作表对象Sheet sheet = workbook.createSheet(sheetName);// 设置列宽sheet.setDefaultColumnWidth(13);// 设置单元格格式CellStyle cellStyle = workbook.createCellStyle();// 内容居中cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);cellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 背景色cellStyle.setFillForegroundColor(IndexedColors.PALE_BLUE.getIndex());cellStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);// 边框颜色 黑色cellStyle.setTopBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setLeftBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setRightBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setBottomBorderColor(IndexedColors.BLACK.getIndex());// 边框线型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// 数据表头字段Map<Integer,String> dataHeadMap = new HashMap<>();dataHeadMap.put(0, "班级");dataHeadMap.put(1, "姓名");dataHeadMap.put(2, "性别");dataHeadMap.put(3, "年龄");dataHeadMap.put(4, "身高");dataHeadMap.put(5, "体重");dataHeadMap.put(6, "家庭地址");dataHeadMap.put(7, "饭卡余额");dataHeadMap.put(8, "备注1");dataHeadMap.put(9, "备注2");// 报表数据项表头样式Row row = sheet.createRow(0);if (dataHeadMap != null) {for (Map.Entry<Integer, String> headMap : dataHeadMap.entrySet()) {Cell cell = row.createCell(headMap.getKey());cell.setCellValue(headMap.getValue());if (null != cellStyle) {cell.setCellStyle(cellStyle);}}}// 以流的方式写出文件try {os = new FileOutputStream(filePath);workbook.write(os);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {if (os != null) {try {os.close();} catch (IOException e) {e.printStackTrace();}}}}

代码结果

8.生成数据内容

8.1在生成数据内容的时候，如果是类似数据表头的形式，则可以利用Map<Integer,String>让key的值和列的顺序保持一致，value为单元格内容,参照数据表头的内容；
8.2可以采用反射的方式生成数据内容，定义一个对象并提供set，get方法，属性的类型尽量是字符串类型(在使用反射的时候，如果属性内容为空，则会有默认值，与实际情况不符)，对象的属性和Excel列的顺序保持一致。
8.2.1定义对象

public class Student {private String className;private String name;private String sex;private int age;private double height;private double weight;private String address;private BigDecimal amount;private String remark1;private String remark2;public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public double getHeight() {return height;}public void setHeight(double height) {this.height = height;}public double getWeight() {return weight;}public void setWeight(double weight) {this.weight = weight;}public String getAddress() {return address;}public void setAddress(String address) {this.address = address;}public BigDecimal getAmount() {return amount;}public void setAmount(BigDecimal amount) {this.amount = amount;}public String getRemark1() {return remark1;}public void setRemark1(String remark1) {this.remark1 = remark1;}public String getRemark2() {return remark2;}public void setRemark2(String remark2) {this.remark2 = remark2;}
}

8.2.2设置数据公共方法

 /*** 设置单元格内容List** @param sheet 工作表对象* @param beginRow 数据从第几行开始* @param dataList 数据集合* @param dataStyle 数据样式* @return*/public static void setDataList(Sheet sheet, int beginRow, Collection dataList, CellStyle dataStyle) {if (dataList != null) {Iterator iterator = dataList.iterator();while (iterator.hasNext()) {Row row = sheet.createRow(beginRow);beginRow++;Object t = iterator.next();// 利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值Field[] fields = t.getClass().getDeclaredFields();try {for (short i = 0; i < fields.length; i++) {Cell cell = row.createCell(i);Field field = fields[i];field.setAccessible(true);String fieldName = field.getName();String getMethodName = "get"+ fieldName.substring(0, 1).toUpperCase()+ fieldName.substring(1);Class clazz = t.getClass();Method method = clazz.getMethod(getMethodName, null);Object cellValue = method.invoke(t, null);if (cellValue instanceof BigDecimal) {DecimalFormat df1 = new DecimalFormat("##,##0.00");cell.setCellValue(df1.format(cellValue));} else if (cellValue instanceof Integer) {cell.setCellValue(Integer.valueOf(cellValue.toString()));} else if(cellValue instanceof Double){cell.setCellValue(Double.parseDouble(String.valueOf(cellValue)));}else {cell.setCellValue(String.valueOf(cellValue));}cell.setCellStyle(dataStyle);}} catch (NoSuchMethodException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}}}}

8.2.3数据表头和数据整体代码

 public static void setDataHead(){String filePath = "/Users/lavined/Desktop/test01.xls";FileOutputStream os = null;// 工作表名称String sheetName = "学生信息表";// 创建工作簿对象Workbook workbook = new HSSFWorkbook();// 创建工作表对象Sheet sheet = workbook.createSheet(sheetName);// 设置列宽sheet.setDefaultColumnWidth(13);// 设置单元格格式CellStyle cellStyle = workbook.createCellStyle();// 内容居中cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);cellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 背景色cellStyle.setFillForegroundColor(IndexedColors.PALE_BLUE.getIndex());cellStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);// 边框颜色 黑色cellStyle.setTopBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setLeftBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setRightBorderColor(IndexedColors.BLACK.getIndex());cellStyle.setBottomBorderColor(IndexedColors.BLACK.getIndex());// 边框线型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// 数据表头字段Map<Integer,String> dataHeadMap = new HashMap<>();dataHeadMap.put(0, "班级");dataHeadMap.put(1, "姓名");dataHeadMap.put(2, "性别");dataHeadMap.put(3, "年龄");dataHeadMap.put(4, "身高");dataHeadMap.put(5, "体重");dataHeadMap.put(6, "家庭地址");dataHeadMap.put(7, "饭卡余额");dataHeadMap.put(8, "备注1");dataHeadMap.put(9, "备注2");// 报表数据项表头样式Row row = sheet.createRow(0);if (dataHeadMap != null) {for (Map.Entry<Integer, String> headMap : dataHeadMap.entrySet()) {Cell cell = row.createCell(headMap.getKey());cell.setCellValue(headMap.getValue());if (null != cellStyle) {cell.setCellStyle(cellStyle);}}}// 数据内容List dataList = new ArrayList();Student student = new Student();student.setClassName("三年级一班");student.setName("姓名");student.setSex("男");student.setAge(10);student.setHeight(120.3);student.setWeight(40.2);student.setAddress("xx省xx市xx县");student.setAmount(new BigDecimal("1000.3"));student.setRemark1("备注111111");student.setRemark2("备注222222");for (int i = 0; i < 20; i++) {dataList.add(student);}// 数据居中CellStyle dataCellStyle = workbook.createCellStyle();dataCellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);dataCellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);setDataList(sheet,1,dataList,dataCellStyle);// 以流的方式写出文件try {os = new FileOutputStream(filePath);workbook.write(os);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {if (os != null) {try {os.close();} catch (IOException e) {e.printStackTrace();}}}}

8.2.3结果

9.整体代码(里面有冗余代码，根据需要自行提取方法)

 public static void writeToExcel(){// 文件路径，03版的文件名以.xls结尾，07版的文件名以.xlsx结尾String filePath = "/Users/lavined/Desktop/test01.xls";FileOutputStream os = null;// 最大列数int cellNum = 10;int cellNumTemp = cellNum - 1;// 工作表名称String sheetName = "学生信息表";// 创建工作簿对象Workbook workbook = new HSSFWorkbook();// 创建工作表对象Sheet sheet = workbook.createSheet(sheetName);// 设置列宽sheet.setDefaultColumnWidth(13);// 设置单元格格式CellStyle cellStyle = workbook.createCellStyle();// 边框颜色白色cellStyle.setTopBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setLeftBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setRightBorderColor(IndexedColors.WHITE.getIndex());cellStyle.setBottomBorderColor(IndexedColors.WHITE.getIndex());// 边框线型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// 由于采用无边框样式以后，最后一个单元格的右边框会消失，所以给最后一个单元格的下一个单元格设置样式CellStyle leftCellStyle = workbook.createCellStyle();leftCellStyle.setLeftBorderColor(IndexedColors.GREY_25_PERCENT.getIndex());leftCellStyle.setBorderLeft(HSSFCellStyle.BORDER_THIN);// 内容居中cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);cellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 设置单元格格式CellStyle cellStyle1 = workbook.createCellStyle();// 内容居中cellStyle1.setAlignment(HSSFCellStyle.ALIGN_CENTER);cellStyle1.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 背景色cellStyle1.setFillForegroundColor(IndexedColors.PALE_BLUE.getIndex());cellStyle1.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);// 边框颜色 黑色cellStyle1.setTopBorderColor(IndexedColors.BLACK.getIndex());cellStyle1.setLeftBorderColor(IndexedColors.BLACK.getIndex());cellStyle1.setRightBorderColor(IndexedColors.BLACK.getIndex());cellStyle1.setBottomBorderColor(IndexedColors.BLACK.getIndex());// 边框线型cellStyle1.setBorderBottom(HSSFCellStyle.BORDER_THIN); //下边框cellStyle1.setBorderLeft(HSSFCellStyle.BORDER_THIN);//左边框cellStyle1.setBorderTop(HSSFCellStyle.BORDER_THIN);//上边框cellStyle1.setBorderRight(HSSFCellStyle.BORDER_THIN);//右边框// 设置字体Font font = workbook.createFont();font.setBold(true);// 粗体font.setFontHeightInPoints((short) 14);// 设置字体大小cellStyle.setFont(font);// 创建行对象Row row = sheet.createRow(0);for (int i = 0; i < cellNum; i++) {// 创建单元格对象Cell cell = row.createCell(i);if (i == 0) {cell.setCellValue(sheetName);}// 设置单元格样式cell.setCellStyle(cellStyle);}row.createCell(cellNum).setCellStyle(leftCellStyle);// 合并单元格CellRangeAddress region1 = new CellRangeAddress(0, 0, 0, cellNumTemp);sheet.addMergedRegion(region1);// 空一行sheet.createRow(1);CellRangeAddress region2 = new CellRangeAddress(1, 1, 0, cellNumTemp);sheet.addMergedRegion(region2);// 第二级表头Row sheetRow2 = sheet.createRow(2);int lastRemarkCellNum = cellNum - 3;for (int i = 0; i < cellNum; i++) {Cell cell = sheetRow2.createCell(i);if (i == 0) {cell.setCellValue("班级：三年级一班");}if (i == 3) {cell.setCellValue("人数：10人");}if (i == lastRemarkCellNum) {cell.setCellValue("创建时间：2021-03-01 17:09:47");}// 设置单元格样式cell.setCellStyle(cellStyle);}sheetRow2.createCell(cellNum).setCellStyle(leftCellStyle);// 合并单元格CellRangeAddress region3 = new CellRangeAddress(2, 2, 0, 2);sheet.addMergedRegion(region3);CellRangeAddress region4 = new CellRangeAddress(2, 2, 3, lastRemarkCellNum -1);sheet.addMergedRegion(region4);CellRangeAddress region5 = new CellRangeAddress(2, 2, lastRemarkCellNum, cellNumTemp);sheet.addMergedRegion(region5);sheet.createRow(3);CellRangeAddress region6 = new CellRangeAddress(3, 3, 0, cellNumTemp);sheet.addMergedRegion(region6);// 数据表头字段Map<Integer,String> dataHeadMap = new HashMap<>();dataHeadMap.put(0, "班级");dataHeadMap.put(1, "姓名");dataHeadMap.put(2, "性别");dataHeadMap.put(3, "年龄");dataHeadMap.put(4, "身高");dataHeadMap.put(5, "体重");dataHeadMap.put(6, "家庭地址");dataHeadMap.put(7, "饭卡余额");dataHeadMap.put(8, "备注1");dataHeadMap.put(9, "备注2");// 报表数据项表头样式Row row1 = sheet.createRow(4);if (dataHeadMap != null) {for (Map.Entry<Integer, String> headMap : dataHeadMap.entrySet()) {Cell cell = row1.createCell(headMap.getKey());cell.setCellValue(headMap.getValue());if (null != cellStyle) {cell.setCellStyle(cellStyle1);}}}// 数据内容List dataList = new ArrayList();Student student = new Student();student.setClassName("三年级一班");student.setName("姓名");student.setSex("男");student.setAge(10);student.setHeight(120.3);student.setWeight(40.2);student.setAddress("xx省xx市xx县");student.setAmount(new BigDecimal("1000.3"));student.setRemark1("备注111111");student.setRemark2("备注222222");for (int i = 0; i < 20; i++) {dataList.add(student);}// 数据居中CellStyle dataCellStyle = workbook.createCellStyle();dataCellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);dataCellStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);setDataList(sheet,5,dataList,dataCellStyle);// 以流的方式写出文件try {os = new FileOutputStream(filePath);workbook.write(os);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}finally {if (os != null) {try {os.close();} catch (IOException e) {e.printStackTrace();}}}}

9.1整体效果

10测试对比

10.1不同版本最大行,最大列

10.1.2超过最大行列则报错

10.2XSSFWorkbook与SXSSFWorkbook效率对比
07版本50万条10秒
07S版本50万条1秒
差别还是有的。