java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();
    	}
    }