import java.io.OutputStream;  import java.lang.reflect.Method;  import java.text.SimpleDateFormat;  import java.util.Collection;  import java.util.Date;  import java.util.regex.Matcher;  import java.util.regex.Pattern;    import org.apache.poi.hssf.usermodel.HSSFCell;  import org.apache.poi.hssf.usermodel.HSSFCellStyle;  import org.apache.poi.hssf.usermodel.HSSFClientAnchor;  import org.apache.poi.hssf.usermodel.HSSFFont;  import org.apache.poi.hssf.usermodel.HSSFPatriarch;  import org.apache.poi.hssf.usermodel.HSSFRichTextString;  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.HSSFColor;  import org.apache.poi.hssf.util.Region;  /**   *   * @author Bruce Xu   *   * @param <T>   */  public class ExcelUtil<T> {              /**        * 导出Excel的方法        * @param title excel中的sheet名称        * @param headers 表头        * @param result 结果集        * @param out 输出流        * @param pattern 时间格式        * @throws Exception        */         public void exportExcel(String title, String[] headers,String[] columns, Collection<T> result, OutputStream out, String pattern) throws Exception{             // 声明一个工作薄             HSSFWorkbook workbook = new HSSFWorkbook();             // 生成一个表格             HSSFSheet sheet = workbook.createSheet(title);             // 设置表格默认列宽度为20个字节             sheet.setDefaultColumnWidth((short)20);                                       // 生成一个样式             HSSFCellStyle style = workbook.createCellStyle();             // 设置这些样式             style.setFillForegroundColor(HSSFColor.GOLD.index);             style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);             style.setBorderBottom(HSSFCellStyle.BORDER_THIN);             style.setBorderLeft(HSSFCellStyle.BORDER_THIN);             style.setBorderRight(HSSFCellStyle.BORDER_THIN);             style.setBorderTop(HSSFCellStyle.BORDER_THIN);             style.setAlignment(HSSFCellStyle.ALIGN_CENTER);             // 生成一个字体             HSSFFont font = workbook.createFont();             font.setColor(HSSFColor.VIOLET.index);             //font.setFontHeightInPoints((short) 12);             font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);             // 把字体应用到当前的样式             style.setFont(font);                          // 指定当单元格内容显示不下时自动换行             style.setWrapText(true);                        // 声明一个画图的顶级管理器            HSSFPatriarch patriarch = sheet.createDrawingPatriarch();           /*                        以下可以用于设置导出的数据的样式                        // 生成并设置另一个样式           HSSFCellStyle style2 = workbook.createCellStyle();           style2.setFillForegroundColor(HSSFColor.LIGHT_YELLOW.index);           style2.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);           style2.setBorderBottom(HSSFCellStyle.BORDER_THIN);           style2.setBorderLeft(HSSFCellStyle.BORDER_THIN);           style2.setBorderRight(HSSFCellStyle.BORDER_THIN);           style2.setBorderTop(HSSFCellStyle.BORDER_THIN);           style2.setAlignment(HSSFCellStyle.ALIGN_CENTER);           style2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);           // 生成另一个字体           HSSFFont font2 = workbook.createFont();           font2.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);           // 把字体应用到当前的样式           style2.setFont(font2);           // 声明一个画图的顶级管理器           HSSFPatriarch patriarch = sheet.createDrawingPatriarch();                                 // 定义注释的大小和位置,详见文档           HSSFComment comment = patriarch.createComment(new HSSFClientAnchor(0, 0, 0, 0, (short) 4, 2, (short) 6, 5));           // 设置注释内容           comment.setString(new HSSFRichTextString("可以在POI中添加注释！"));           // 设置注释作者，当鼠标移动到单元格上是可以在状态栏中看到该内容.           comment.setAuthor("leno");*/                                       // 产生表格标题行             //表头的样式           HSSFCellStyle titleStyle = workbook.createCellStyle();// 创建样式对象           titleStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER_SELECTION);// 水平居中           titleStyle.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);// 垂直居中           // 设置字体           HSSFFont titleFont = workbook.createFont(); // 创建字体对象           titleFont.setFontHeightInPoints((short) 15); // 设置字体大小           titleFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);// 设置粗体         //  titleFont.setFontName("黑体"); // 设置为黑体字           titleStyle.setFont(titleFont);           sheet.addMergedRegion(new Region(0,(short)0,0,(short)(headers.length-1)));//指定合并区域            HSSFRow rowHeader = sheet.createRow(0);             HSSFCell cellHeader = rowHeader.createCell((short)0);   //只能往第一格子写数据，然后应用样式，就可以水平垂直居中           HSSFRichTextString textHeader = new HSSFRichTextString(title);             cellHeader.setCellStyle(titleStyle);           cellHeader.setCellValue(textHeader);                      HSSFRow row = sheet.createRow(1);             for (int i = 0; i < headers.length; i++) {                 HSSFCell cell = row.createCell((short)i);                 cell.setCellStyle(style);                 HSSFRichTextString text = new HSSFRichTextString(headers[i]);                 cell.setCellValue(text);              }              // 遍历集合数据，产生数据行              if(result != null){                  int index = 2;                  for(T t:result){                 //  Field[] fields = t.getClass().getDeclaredFields();                    row = sheet.createRow(index);                      index++;                    for(short i = 0; i < columns.length; i++) {                        HSSFCell cell = row.createCell(i);   //                   Field field = fields[i];   //                   String fieldName = field.getName();                        String fieldName = columns[i];                        String getMethodName = "get"                            + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);                        Class tCls = t.getClass();                        Method getMethod = tCls.getMethod(getMethodName, new Class[]{});                       // getMethod.getReturnType().isInstance(obj);                       Object value = getMethod.invoke(t, new Class[]{});                        String textValue = null;                        if(value == null) {                            textValue = "";                        }else if (value instanceof Date) {                            Date date = (Date) value;                            SimpleDateFormat sdf = new SimpleDateFormat(pattern);                             textValue = sdf.format(date);                         }  else if (value instanceof byte[]) {                            // 有图片时，设置行高为60px;                            row.setHeightInPoints(60);                            // 设置图片所在列宽度为80px,注意这里单位的一个换算                            sheet.setColumnWidth(i, (short) (35.7 * 80));                            // sheet.autoSizeColumn(i);                            byte[] bsValue = (byte[]) value;                            HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0,                                  1023, 255, (short) 6, index, (short) 6, index);                            anchor.setAnchorType(2);                            patriarch.createPicture(anchor, workbook.addPicture(                                  bsValue, HSSFWorkbook.PICTURE_TYPE_JPEG));                         } else{                            //其它数据类型都当作字符串简单处理                            textValue = value.toString();                         }                                                if(textValue!= null){                            Pattern p = Pattern.compile("^//d+(//.//d+)?$");                              Matcher matcher = p.matcher(textValue);                            if(matcher.matches()){                               //是数字当作double处理                               cell.setCellValue(Double.parseDouble(textValue));                            }else{                               HSSFRichTextString richString = new HSSFRichTextString(textValue);   //                            HSSFFont font3 = workbook.createFont();   //                            font3.setColor(HSSFColor.BLUE.index);   //                            richString.applyFont(font3);                               cell.setCellValue(richString);                            }                         }                    }                }                 }              workbook.write(out);          }      }       

调用示例：以springmvc为例，导出数据库记录到Excel,弹出下载对话框

@RequestMapping(value="/exprotExcel")   public @ResponseBody String exprotExcel(HttpServletResponse response,NjWorkLog njWorkLog,@RequestParam(value="createUserIds",required=false) String createUserIds,@RequestParam(value="workLogGrantUsersName",required=false)String workLogGrantUsersName,@RequestParam(value="strWorkEndDate",required=false)String strWorkEndDate)   {        ExcelUtil<NjWorkLog> excelUtil=new ExcelUtil<NjWorkLog>();    OutputStream out=null;    try    {     out = response.getOutputStream();// 取得输出流       //out.flush();               response.reset();// 清空输出流                   response.setHeader("Content-disposition", "attachment; filename="+new String("工作日志".getBytes("GB2312"),"8859_1")+".xls");// 设定输出文件头                 response.setContentType("application/msexcel");// 定义输出类型      }  catch (IOException e)    {     e.printStackTrace();    }     String[] headers ={"跟踪目标","工作时间","事项类型","项目名称","完成情况自述","工作量","进度","配合人员","加班","作者","附件名称"};    String[]columns={ "strTarget", "strWorkDate", "dictTypeId", "projectId", "strDesc", "bdWorkload", "strSchedule", "strCooperate","isOverTime","createUserId", "strFileName"};    if("on".equals(njWorkLog.getIsOverTime()))     njWorkLog.setIsOverTime("1");    else     njWorkLog.setIsOverTime("");    if(StringUtils.isNotBlank(createUserIds))     njWorkLog.setTempArray(createUserIds.split(","));    List<NjWorkLog> dataset=njWorkLogService.findMyAttentionExcel(njWorkLog);        try    {     excelUtil.exportExcel("工作日志", headers, columns, dataset, out, "");         } catch (Exception e1)    {     e1.printStackTrace();    }    try    {     out.close();    } catch (IOException e)    {     e.printStackTrace();    }    return null;   }