java生成Excel文件，下载

1. pom引入poi的maven依赖

   
   org.apache.poi
   poi
   3.15
   

2. 单元格的创建，设置样式和赋值

   package com.yl;

   import java.io.FileOutputStream;
   import java.io.IOException;

   import org.apache.poi.hssf.usermodel.HSSFCell;
   import org.apache.poi.hssf.usermodel.HSSFCellStyle;
   import org.apache.poi.hssf.usermodel.HSSFRow;
   import org.apache.poi.hssf.usermodel.HSSFSheet;
   import org.apache.poi.hssf.usermodel.HSSFWorkbook;
   import org.apache.poi.hssf.util.CellRangeAddress;

   @SuppressWarnings("deprecation")
   public class Book1 {

   public static void main(String[] args) {
   HSSFWorkbook workbook = new HSSFWorkbook(); // 创建一个excel
   HSSFSheet sheet = workbook.createSheet("sheet1");// 新建sheet页

   HSSFCellStyle cellStyle = workbook.createCellStyle(); // 新建单元格样式
   cellStyle.setFillForegroundColor((short) 13);// 设置背景色
   cellStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
   cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 居中
   cellStyle.setWrapText(true);// 设置自动换行

   HSSFRow titleRow = sheet.createRow(0);
   CellRangeAddress cra1 = new CellRangeAddress(0, 0, 0, 5);
   sheet.addMergedRegion(cra1);
   titleRow.createCell(0).setCellValue("haha1");
   CellRangeAddress cra2 = new CellRangeAddress(0, 0, 6, 11);
   sheet.addMergedRegion(cra2);
   titleRow.createCell(6).setCellValue("haha2");
   CellRangeAddress cra3 = new CellRangeAddress(0, 0, 12, 17);
   sheet.addMergedRegion(cra3);
   titleRow.createCell(12).setCellValue("haha3");
   CellRangeAddress cra4 = new CellRangeAddress(0, 0, 18, 23);
   sheet.addMergedRegion(cra4);
   titleRow.createCell(18).setCellValue("haha4");
   CellRangeAddress cra5 = new CellRangeAddress(0, 0, 24, 29);
   sheet.addMergedRegion(cra5);

   titleRow.createCell(24).setCellValue("haha5");

   HSSFRow row = sheet.createRow(1);
   // 参数1：起始行 参数2：终止行 参数3：起始列 参数4：终止列
   CellRangeAddress region1 = new CellRangeAddress(1, 5, 0, 5);

   sheet.addMergedRegion(region1);
   HSSFCell cellB1 = row.createCell(0);
   cellB1.setCellValue("B1");

   CellRangeAddress region2 = new CellRangeAddress(1, 5, 6, 11);
   sheet.addMergedRegion(region2);
   // HSSFRow row1 = sheet.createRow(0);//不要再重新创建行数了，这样会把之前填充的数据删除掉！
   HSSFCell cellB2 = row.createCell(6);
   cellB2.setCellValue("B2");

   CellRangeAddress region3 = new CellRangeAddress(1, 5, 12, 17);
   sheet.addMergedRegion(region3);
   // HSSFRow row1 = sheet.createRow(0);//不要再重新创建行数了，这样会把之前填充的数据删除掉！
   HSSFCell cellB3 = row.createCell(12);
   cellB3.setCellValue("B3");

   CellRangeAddress region4 = new CellRangeAddress(1, 5, 18, 23);
   sheet.addMergedRegion(region4);
   // HSSFRow row1 = sheet.createRow(0);//不要再重新创建行数了，这样会把之前填充的数据删除掉！
   HSSFCell cellB4 = row.createCell(18);
   cellB4.setCellValue("B4");

   // 输出到本地
   String excelName = "myExcel.xls";
   FileOutputStream out = null;
   try {
   out = new FileOutputStream(excelName);
   workbook.write(out);
   out.flush();
   out.close();
   } catch (Exception e) {
   e.printStackTrace();
   } finally {
   if (out != null)
   try {
   out.close();
   } catch (IOException e) {
   e.printStackTrace();
   }
   out = null;
   System.out.println("导出成功");
   }

   }

   }

3. 将文件在网页上导出：

   // POI导出流文件下载
   public static void downloadExcel(HSSFWorkbook workbook, HttpServletResponse response, String filename)
   throws IOException {
   try {
   OutputStream out = response.getOutputStream();
   response.setHeader("Content-disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
   response.setContentType("application/msexcel;charset=UTF-8");
   workbook.write(out);
   out.flush();
   out.close();
   } catch (IOException e) {
   e.printStackTrace();
   }
   }