本文假定 Excel 文件中保存的是员工数据，并且数据中带有员工的头像。代码支持的图片格式有png、bmp、jpg、gif。但是这里需要注意，有些网站上下载的图片虽然后缀名是 jpg，但是文件二进制内容的格式是 WebP 的。Java8 目前官方api不支持 WebP ，本文不涉及webp相关话题，本文代码也不支持 WebP 格式。
另外我还遇到个坑，POI 5.2.5 在处理部分 jpg 格式图片的时候，无法把图片输出到 Excel 文件。为了解决这个问题，我在代码中把所有图片强行转成 png，保存为硬盘上的临时文件，再重新输出到 Excel 文件中。这个问题我没有在 POI 4.1.2 版本遇到过。
POI 的接口是线程不安全的，多个线程同时向一个文件输出会造成错误。如果读者想要在多线程环境（比如网站后端）使用下面的代码，要么使用锁，要么确保各个线程输出不同的文件。
本文的代码计算了图片的缩放比例，并且使用 picture.resize(scaleX, scaleY); 方法来设置图片缩放比例。这也与 POI 4.1.2 版本不同。POI 4.1.2 版本使用 picture.resize(1, 1); 会自动缩放图片调整成合适大小。
员工的 DTO 类：
/*** 员工DTO*/
public class EmployeeDTO {// 工号private String no;// 姓名private String name;// 性别private String gender;// 头像private String portrait;@Overridepublic String toString() {final StringBuffer sb = new StringBuffer("Employee{");sb.append("no='").append(no).append('\'');sb.append(", name='").append(name).append('\'');sb.append(", gender='").append(gender).append('\'');sb.append(", portrait='").append(portrait).append('\'');sb.append('}');return sb.toString();}public String getNo() {return no;}public void setNo(String no) {this.no = no;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public String getPortrait() {return portrait;}public void setPortrait(String portrait) {this.portrait = portrait;}
}用来生成Excel 文件的 ImageExcelUtils 类
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.ClientAnchor;
import org.apache.poi.ss.usermodel.CreationHelper;
import org.apache.poi.ss.usermodel.Drawing;
import org.apache.poi.ss.usermodel.Font;
import org.apache.poi.ss.usermodel.HorizontalAlignment;
import org.apache.poi.ss.usermodel.Picture;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.VerticalAlignment;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.util.IOUtils;
import org.apache.poi.xssf.streaming.SXSSFWorkbook;import javax.imageio.ImageIO;public class ImageExcelUtils {/*** 读取jpg图片* @param path 图片文件路径* @return BufferedImage*/public static BufferedImage readBufferedImage(String path) {BufferedImage originImage = null;BufferedImage result = null;try {File file = new File(path);originImage = ImageIO.read(file);// 确保图片颜色只有RGB，没有alpha透明度result = new BufferedImage(originImage.getWidth(),originImage.getHeight(),BufferedImage.TYPE_INT_RGB);result.getGraphics().drawImage(originImage, 0, 0, null);} catch (IOException e) {e.printStackTrace();}return result;}/*** 设置excel文件的图片* @param workbook 工作簿* @param sheet sheet页* @param imgFilePath 图片文件路径* @param row1 图片起始的行* @param col1 图片起始的列* @param tempFilePath 临时文件路径*/public static void setExcelImg(Workbook workbook, Sheet sheet, String imgFilePath,int row1, int col1, int width, int height, String tempFilePath) {File file = new File(imgFilePath);if (!file.exists()) {return;}// 临时文件File tempFile = new File(tempFilePath);if (tempFile.exists()) {tempFile.delete();}FileInputStream inputStream = null;boolean isClose = false;try {BufferedImage bufferedImage = readBufferedImage(imgFilePath);int imageWidth = bufferedImage.getWidth();int imageHeight = bufferedImage.getHeight();ImageIO.write(bufferedImage, "png", tempFile);inputStream = new FileInputStream(tempFile);//利用POI提供的工具类把文件流转化成二进制数据byte[] bytes = IOUtils.toByteArray(inputStream);//向POI内存中添加一张图片，返回图片在图片集合中的索引int pictureIndex = workbook.addPicture(bytes, Workbook.PICTURE_TYPE_PNG);//参数一：图片的二进制数据，参数二：图片类型//从Workbook中得到绘制图片的工具类CreationHelper helper = workbook.getCreationHelper();//创建锚点，设置图片坐标ClientAnchor clientAnchor = helper.createClientAnchor();clientAnchor.setAnchorType(ClientAnchor.AnchorType.DONT_MOVE_AND_RESIZE);clientAnchor.setRow1(row1); // 设置起始行clientAnchor.setCol1(col1); // 设置起始列//从sheet对象中得到一个绘图对象Drawing<?> drawingPatriarch = sheet.createDrawingPatriarch();//绘制图片，锚点，图片在内存中的位置Picture picture = drawingPatriarch.createPicture(clientAnchor, pictureIndex);// 使用固定的长宽比例系数double scaleX = 1.0;double scaleY = 1.0;if (imageWidth <= width && imageHeight <= height) {scaleX = 1.0;scaleY = 1.0;} else {scaleX = (double) width / (double) imageWidth;scaleY = (double) height / (double) imageHeight;double min = Math.min(scaleX, scaleY);scaleX = scaleY = min;}picture.resize(scaleX, scaleY);//自适应渲染图片} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {try {if (inputStream != null && !isClose) {inputStream.close();}tempFile.delete();} catch (IOException e) {e.printStackTrace();}}}/*** 创建Excel文件* @param employeeDTOList 员工列表* @param file 输出的 Excel 文件* @param tempFilePath 临时文件路径*/public static void createExcelFile(List<EmployeeDTO> employeeDTOList, File file, String tempFilePath) {//创建工作簿，excel2007版本的，如果是excel2003的话。创建的对象是：HSSFWorkbookWorkbook workbook = new SXSSFWorkbook();//创建sheetSheet sheet = workbook.createSheet("picture sheet");// 列宽分别是25个字符和40个字符，一字符等于 6.107 像素sheet.setColumnWidth(0, 25 * 256);sheet.setColumnWidth(1, 25 * 256);sheet.setColumnWidth(2, 25 * 256);sheet.setColumnWidth(3, 40 * 256);// 行高是 120 磅，1磅是 1.34039 像素sheet.setDefaultRowHeightInPoints(120f);// 设置字体，黑体Font font = workbook.createFont();font.setFontName("黑体");// 字体加粗font.setBold(true);CellStyle cellStyle = workbook.createCellStyle();cellStyle.setFont(font);cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);cellStyle.setAlignment(HorizontalAlignment.CENTER);// 表格标题行Row firstRow = sheet.createRow(0);Cell r0c0 = firstRow.createCell(0);r0c0.setCellValue("工号");Cell r0c1 = firstRow.createCell(1);r0c1.setCellValue("姓名");Cell r0c2 = firstRow.createCell(2);r0c2.setCellValue("性别");Cell r0c3 = firstRow.createCell(3);r0c3.setCellValue("头像");r0c0.setCellStyle(cellStyle);r0c1.setCellStyle(cellStyle);r0c2.setCellStyle(cellStyle);r0c3.setCellStyle(cellStyle);int size = employeeDTOList.size();for (int i = 0; i < size; i++) {EmployeeDTO dto = employeeDTOList.get(i);int rowIndex = i + 1;Row row = sheet.createRow(rowIndex);Cell c0 = row.createCell(0);Cell c1 = row.createCell(1);Cell c2 = row.createCell(2);Cell c3 = row.createCell(3);// 向excel中输入图片String portrait = dto.getPortrait();if (null != portrait && portrait.trim().length() > 0) {portrait = portrait.trim();setExcelImg(workbook, sheet, portrait, rowIndex, 3, 244, 160, tempFilePath);}c0.setCellValue(dto.getNo());c1.setCellValue(dto.getName());c2.setCellValue(dto.getGender());}//创建文件输入流FileOutputStream out = null;//创建文件输出流try {out = new FileOutputStream(file);//调用工作簿的write创建excelworkbook.write(out);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();} finally {try {if (out != null) {out.flush();out.close();out = null;}} catch (IOException e) {e.printStackTrace();}} // end finally}
}包含 main 方法的 Test 类，测试具体效果
import java.io.File;
import java.util.List;
import java.util.ArrayList;public class Test {public static void main(String[] args) {List<EmployeeDTO> employeeDTOList = new ArrayList<>();EmployeeDTO emp_1 = new EmployeeDTO();emp_1.setNo("1");emp_1.setName("张三");emp_1.setGender("男");emp_1.setPortrait("D:/1715284526222417922.jpg");EmployeeDTO emp_2 = new EmployeeDTO();emp_2.setNo("2");emp_2.setName("李四");emp_2.setGender("男");emp_2.setPortrait("D:\\bmptest.bmp");EmployeeDTO emp_3 = new EmployeeDTO();emp_3.setNo("3");emp_3.setName("王二");emp_3.setGender("女");emp_3.setPortrait("D:\\113.jpg");EmployeeDTO emp_4 = new EmployeeDTO();emp_4.setNo("4");emp_4.setName("涂军");emp_4.setGender("男");emp_4.setPortrait("D:\\309446533.gif");employeeDTOList.add(emp_1);employeeDTOList.add(emp_2);employeeDTOList.add(emp_3);employeeDTOList.add(emp_4);File file = new File("D:\\ws\\tmpdir\\out.xlsx");String tempFilePath = "D:\\ws\\tmpdir\\temp.png";ImageExcelUtils.createExcelFile(employeeDTOList, file, tempFilePath);}
}
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