Java POI生成Excel文件，下载

1、pom引入poi的maven依赖

 <dependency>
     <groupId>org.apache.poi</groupId>
     <artifactId>poi</artifactId>
     <version>3.15</version>
 </dependency>

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();
     }
 }