Dynamically merge tables based on poi
- First look at the effect diagram.
The left side is the main table data, and the right side is the sub-table data. You can modify it according to your needs. Let's look at the code below.
- Introduce dependencies
<!--poi-->
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>4.1.0</version>
</dependency>
- Create a PoiExcel class
First construct the data. According to the table, the main and sub-tables are related, so the data of the main and sub-tables is stored in a map collection. The value of the main table is used as the key of the map, and the value corresponds to the list collection of the sub-tables. You can refer to the following code:
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("20210212-于丽-电子信息工程",childList1);
masterList.add(map);
Then create an Excel workbook object
//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);
Then fill the worksheet with data line by line according to the requirements, first is the complex header, the first line is the main table and sub-table, the main table and sub-table are merged columns, determined according to the length of the main and sub-table headers, the number of merged columns; The second line is the header, which is filled according to the array of main and sub headers.
//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]);
}
In this way, the headers of the first row and the second row are filled, and then the corresponding data is filled. The main table is filled first. I use "-" to separate the values of the main table, so use a string Cut into an array, and then get the main table data and the corresponding sub-table data. The first two rows of the workbook are headers, so the filling data starts from the third row, so the row subscript is 2, and then from the third Start to create rows and fill the data in the main table. When filling, you need to judge the size of the list of the sub-table. If it is greater than one, you need to merge. After filling the main table, fill the sub-table. The sub-table does not need to be merged, just fill it line by line. code show as below:
//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]);
}
}
}
}
The most important line of code is:
new CellRangeAddress(int firstRow, int lastRow, int firstCol, int lastCol)
This code is to merge cells, parameter 1: start row parameter 2: end row parameter 3: start column parameter 4: end column
- Finally, look at the complete code of the PoiExcel class
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.ss.usermodel.HorizontalAlignment;
import org.apache.poi.ss.util.CellRangeAddress;
import javax.servlet.http.HttpServletResponse;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.*;
/**
* @author huao
* @Date 2022/8/31 13:50
* @description:
*/
public class PoiExcel {
public static void excelport(HttpServletResponse response) throws Exception {
//数据来源 通过参数传入
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("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);
//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]);
}
}
}
}
String fileName = URLEncoder.encode("POIExcel下载测试","UTF-8");
response.setContentType("application/octet-stream;charset=UTF-8");
response.setHeader("Content-Disposition","attachment;filename="+fileName+".xls");
OutputStream os = response.getOutputStream();
workbook.write(os);
os.flush();
os.close();
workbook.close();
}
}
Then the code of the controller layer:
import com.example.demo.utils.PoiExcel;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletResponse;
/**
* @author huao
* @Date 2022/8/31 13:56
* @description:
*/
@RestController
@RequestMapping("/demo")
public class DemoWeb {
@RequestMapping("/download")
public void download(HttpServletResponse response) throws Exception {
PoiExcel.excelport(response);
}
}
After importing dependencies, the code can be copied and used directly.
Reason for writing: I saw many examples of dynamically merging cells on the Internet, but I couldn’t understand them all. Maybe I’m too good at it, so I made one myself. The amount of code is very small. If there is anything unclear, welcome to comment Leave a message or private message me.