Java使用poi导出excel
- 前言
- 1.Excel和POI对象对应关系：
- 2.POI创建Excel的步骤
- 一、引入依赖
- 二、示例
- 1.准备数据
- 2.创建Excel工作簿对象
- 3.给excel创建表头
- 4.填充数据
- 5.浏览器访问下载excel
- 6.完整代码
前言
有个需求需要后端将数据导出为excel。并且excel中需要合并单元格。于是在网上找到了poi这个包。
首先要根据数据或者excel模板构建出表头。然后将表头和数据想办法进行关联进行循环添加。
效果图：
1.Excel和POI对象对应关系：
| Excel结构 | POI对象 |
|---|---|
| excel 的文档对象 | HSSFWorkbook |
| excel 的表单（sheet） | HSSFSheet |
| excel 的行 | HSSFRow |
| excel 的格子单元 | HSSFCell |
2.POI创建Excel的步骤
- 生成文档对象HSSHWorkbook。
- 通过HSSFWorkbook生成表单HSSFSheet。
- 通过HSSFSheet生成行HSSFRow
- 通过HSSFRow生成单元格HSSFCell。
一、引入依赖
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>3.17</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>3.17</version>
</dependency>
二、示例
1.准备数据
String[] masterHead = {"学号","姓名","专业"};
String[] childHead = {"课程名称","上课地点","任课教师","上课时间"};
List<String[]> childList = new ArrayList<>();
childList.add(new String[]{"Java程序设计","1号楼302","雷老师","2022/8/30 15:53:49"});
childList.add(new String[]{"数据结构","1号楼305","雷老师","2022/8/30 9:18:28"});
List<String[]> childList1 = new ArrayList<>();
childList1.add(new String[]{"计算机网络","2号楼301","方老师","2022/8/30 15:53:49"});
List<Map<String,List<String[]>>> masterList = new ArrayList<>();
Map<String,List<String[]>> map = new HashMap();
map.put("20210211-张晓-计算机与科学",childList);
map.put("20210211-张2-计算机与科学",childList);
map.put("20210212-于丽-电子信息工程",childList1);
masterList.add(map);
2.创建Excel工作簿对象
//创建Excel工作薄对象
HSSFWorkbook workbook=new HSSFWorkbook();
//创建Excel工作表对象
HSSFSheet sheet = workbook.createSheet("wj");
//设置单元格居中
HSSFCellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(HorizontalAlignment.CENTER);
//设置边框
cellStyle.setBorderBottom(BorderStyle.THIN); //下边框
cellStyle.setBorderLeft(BorderStyle.THIN);//左边框
cellStyle.setBorderTop(BorderStyle.THIN);//上边框
cellStyle.setBorderRight(BorderStyle.THIN);//右边框
3.给excel创建表头
然后根据需求一行行来给工作表格填充数据，首先是复杂表头，第一行是主表和子表，主表和子表的是合并列，根据主子表头的长度来确定，合并的列数；第二行是表头，根据主子表头的数组来填充。
//创建行的单元格，从0开始
HSSFRow row = sheet.createRow(0);
//创建统计单元格
HSSFCell masterCell=row.createCell(0);
//赋值
masterCell.setCellValue("主表");
masterCell.setCellStyle(cellStyle);
//合并列
CellRangeAddress region=new CellRangeAddress(0, 0, 0, masterHead.length-1);
sheet.addMergedRegion(region);
//创建详情单元格 从统计单元格的后一格开始创建
HSSFCell childCell = row.createCell(masterHead.length);
//赋值
childCell.setCellValue("子表");
childCell.setCellStyle(cellStyle);
//合并列
region=new CellRangeAddress(0, 0, masterHead.length, masterHead.length+childHead.length-1);
sheet.addMergedRegion(region);
//表头 从1开始
HSSFRow titleRow = sheet.createRow(1);
//主表头
for (int i = 0; i < masterHead.length ; i++) {
HSSFCell msCell = titleRow.createCell(i);
msCell.setCellStyle(cellStyle);
msCell.setCellValue(masterHead[i]);
}
//子表头
for (int i = 0; i < childHead.length; i++) {
HSSFCell chcell = titleRow.createCell(masterHead.length+i);
chcell.setCellStyle(cellStyle);
chcell.setCellValue(childHead[i]);
}
4.填充数据
//填充数据
int lastRowIndex = 2; //记录最后行位置
for (Map<String,List<String[]>> m : masterList){
for (String key : m.keySet()){
String[] ms = key.split("-");
List<String[]> chlist = m.get(key);
HSSFRow valueRow = sheet.createRow(lastRowIndex);
for (int i = 0; i < ms.length ; i++) {
HSSFCell mscell = valueRow.createCell(i);
mscell.setCellStyle(cellStyle);
mscell.setCellValue(ms[i]);
if (chlist.size()>1){ //子表数量大于1才进行 行合并
region=new CellRangeAddress(lastRowIndex, lastRowIndex+chlist.size()-1, i, i);
sheet.addMergedRegion(region);
}
}
for (int i = 0; i < chlist.size(); i++) {
String[] chstrs = chlist.get(i);
HSSFRow chRow;
if (i == 0){ //避免重复创建 覆盖主表数据
chRow = valueRow;
}else {
chRow = sheet.createRow(lastRowIndex);
}
lastRowIndex++;
for (int j = 0; j < chstrs.length; j++) {
HSSFCell chcell = chRow.createCell(ms.length+j);
chcell.setCellStyle(cellStyle);
chcell.setCellValue(chstrs[j]);
}
}
}
}
5.浏览器访问下载excel
//设置下载头部文件信息
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("demo.xls", "UTF-8"));
workbook.write(response.getOutputStream());
response.getOutputStream().close();
6.完整代码
@GetMapping("/")
public void exportExcel(HttpServletResponse response) throws IOException {
String[] masterHead = {"学号","姓名","专业"};
String[] childHead = {"课程名称","上课地点","任课教师","上课时间"};
List<String[]> childList = new ArrayList<>();
childList.add(new String[]{"Java程序设计","1号楼302","雷老师","2022/8/30 15:53:49"});
childList.add(new String[]{"数据结构","1号楼305","雷老师","2022/8/30 9:18:28"});
List<String[]> childList1 = new ArrayList<>();
childList1.add(new String[]{"计算机网络","2号楼301","方老师","2022/8/30 15:53:49"});
List<Map<String,List<String[]>>> masterList = new ArrayList<>();
Map<String,List<String[]>> map = new HashMap();
map.put("20210211-张晓-计算机与科学",childList);
map.put("20210211-张2-计算机与科学",childList);
map.put("20210212-于丽-电子信息工程",childList1);
masterList.add(map);
//创建Excel工作薄对象
HSSFWorkbook workbook=new HSSFWorkbook();
//创建Excel工作表对象
HSSFSheet sheet = workbook.createSheet("wj");
//设置单元格居中
HSSFCellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(HorizontalAlignment.CENTER);
cellStyle.setBorderBottom(BorderStyle.THIN); //下边框
cellStyle.setBorderLeft(BorderStyle.THIN);//左边框
cellStyle.setBorderTop(BorderStyle.THIN);//上边框
cellStyle.setBorderRight(BorderStyle.THIN);//右边框
//创建行的单元格，从0开始
HSSFRow row = sheet.createRow(0);
//创建统计单元格
HSSFCell masterCell=row.createCell(0);
//赋值
masterCell.setCellValue("主表");
masterCell.setCellStyle(cellStyle);
//合并列
CellRangeAddress region=new CellRangeAddress(0, 0, 0, masterHead.length-1);
sheet.addMergedRegion(region);
//创建详情单元格 从统计单元格的后一格开始创建
HSSFCell childCell = row.createCell(masterHead.length);
//赋值
childCell.setCellValue("子表");
childCell.setCellStyle(cellStyle);
//合并列
region=new CellRangeAddress(0, 0, masterHead.length, masterHead.length+childHead.length-1);
sheet.addMergedRegion(region);
//表头 从1开始
HSSFRow titleRow = sheet.createRow(1);
//主表头
for (int i = 0; i < masterHead.length ; i++) {
HSSFCell msCell = titleRow.createCell(i);
msCell.setCellStyle(cellStyle);
msCell.setCellValue(masterHead[i]);
}
//子表头
for (int i = 0; i < childHead.length; i++) {
HSSFCell chcell = titleRow.createCell(masterHead.length+i);
chcell.setCellStyle(cellStyle);
chcell.setCellValue(childHead[i]);
}
//填充数据
int lastRowIndex = 2; //记录最后行位置
for (Map<String,List<String[]>> m : masterList){
for (String key : m.keySet()){
String[] ms = key.split("-");
List<String[]> chlist = m.get(key);
HSSFRow valueRow = sheet.createRow(lastRowIndex);
for (int i = 0; i < ms.length ; i++) {
HSSFCell mscell = valueRow.createCell(i);
mscell.setCellStyle(cellStyle);
mscell.setCellValue(ms[i]);
if (chlist.size()>1){ //子表数量大于1才进行 行合并
region=new CellRangeAddress(lastRowIndex, lastRowIndex+chlist.size()-1, i, i);
sheet.addMergedRegion(region);
}
}
for (int i = 0; i < chlist.size(); i++) {
String[] chstrs = chlist.get(i);
HSSFRow chRow;
if (i == 0){ //避免重复创建 覆盖主表数据
chRow = valueRow;
}else {
chRow = sheet.createRow(lastRowIndex);
}
lastRowIndex++;
for (int j = 0; j < chstrs.length; j++) {
HSSFCell chcell = chRow.createCell(ms.length+j);
chcell.setCellStyle(cellStyle);
chcell.setCellValue(chstrs[j]);
}
}
}
}
//设置下载头部文件信息
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("demo.xls", "UTF-8"));
workbook.write(response.getOutputStream());
response.getOutputStream().close();
}
