Java 工具类之基于 POI 导出 Excel

深碍√TFBOYSˉ_ 2022-05-11 00:26 242阅读 0赞

在平时的Web项目开发中，经常会用到Excel导出功能，在此将其总结为一个简单的工具类，以供平常使用

/**
     * Created with Intellij IDEA.
     *
     * @author potoyang
     * Create: 2018/8/29 10:16
     * Modified By:
     * Description: 依赖于poi构建的excel表格导出工具类
     * 
     * <dependency>
     * <groupId>org.apache.poi</groupId>
     * <artifactId>poi-ooxml</artifactId>
     * <version>3.10-FINAL</version>
     * </dependency>
     */
    public class ExcelExportUtil<T> {
        private Class<T> clazz;
    
        public ExcelExportUtil(Class<T> clazz) {
            this.clazz = clazz;
        }
    
        /**
         * 直接在浏览器输出excel表格
         *
         * @param excelName 导出excel名称
         * @param titles    导出excel的表头
         * @param data      导出excel中的数据
         * @param response  请求输出流
         * @return 是否成功
         */
        public String getExcel(String excelName, String[] titles, List<T> data, HttpServletResponse response) {
            try {
                response.setContentType("application/x-xls;charset=UTF-8");
                Long milliSecond = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
                String fileName = excelName + "-" + milliSecond + ".xls";
                fileName = MimeUtility.encodeText(URLEncoder.encode(fileName, "UTF-8"), "UTF-8", "B");
                response.setHeader("Content-disposition", "attachment;filename=" + fileName);
                ServletOutputStream outputStream = response.getOutputStream();
                HSSFWorkbook workbook = new HSSFWorkbook();
                HSSFSheet hssfSheet = workbook.createSheet("sheet1");
                HSSFRow hssfRow = hssfSheet.createRow(0);
                HSSFCellStyle hssfCellStyle = workbook.createCellStyle();
                hssfCellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
    
                HSSFCell hssfCell;
                for (int i = 0; i < titles.length; i++) {
                    hssfCell = hssfRow.createCell(i);
                    hssfCell.setCellValue(titles[i]);
                    hssfCell.setCellStyle(hssfCellStyle);
                }
    
                // 获取需要写入的数据
                for (int i = 0; i < data.size(); i++) {
                    hssfRow = hssfSheet.createRow(i + 1);
    
                    T t = data.get(i);
                    boolean flag = false;
    
                    Field[] fields = clazz.getDeclaredFields();
                    for (int j = 0; j < fields.length; j++) {
                        String fieldName = fields[j].getName();
                        if ("serialVersionUID".equals(fieldName)) {
                            flag = true;
                            continue;
                        }
                        // 类中需要有类成员的get方法
                        Method method = clazz.getMethod("get" + change(fieldName), (Class<?>[]) null);
                        Object obj = method.invoke(t, (Object[]) null);
                        if (flag) {
                            hssfRow.createCell(j - 1).setCellValue(String.valueOf(obj));
                        } else {
                            hssfRow.createCell(j).setCellValue(String.valueOf(obj));
                        }
                    }
                }
    
                // 输出文件到浏览器
                try {
                    workbook.write(outputStream);
                    outputStream.flush();
                    outputStream.close();
                    return "success";
                } catch (Exception e) {
                    e.printStackTrace();
                    return e.getMessage();
                }
            } catch (Exception e) {
                e.printStackTrace();
                return e.getMessage();
            }
        }
    
        /**
         * @param src 源字符串
         * @return 字符串，将src的第一个字母转换为大写，src为空时返回null
         */
        private String change(String src) {
            if (src != null) {
                StringBuilder stringBuilder = new StringBuilder(src);
                stringBuilder.setCharAt(0, Character.toUpperCase(stringBuilder.charAt(0)));
                return stringBuilder.toString();
            } else {
                return null;
            }
        }
    }

不定时更新，见Github：[ExcelExportUtil.java][]

[ExcelExportUtil.java]: https://github.com/PotoYang/SpringbootLearn/blob/master/file-upload/src/main/java/com/potoyang/learn/fileupload/excel/ExcelExportUtil.java