用poi来导出数据到excel文档

 package cn.com.dyg.work.common.utils;

 import org.apache.poi.hssf.usermodel.HSSFRichTextString;
 import org.apache.poi.hssf.usermodel.HSSFWorkbookFactory;
 import org.apache.poi.ss.usermodel.*;
 import org.apache.poi.ss.util.CellRangeAddress;
 import org.apache.poi.xssf.usermodel.XSSFRichTextString;
 import org.apache.poi.xssf.usermodel.XSSFWorkbookFactory;

 import java.util.List;

 /**
  * 导出Excel公共方法
  *
  * @author yxb
  * @version 1.0
  */
 public class ExportExcelTool {

     //显示的导出表的标题
     private String title;
     //导出表的列名
     private String[] rowName;

     private List<Object[]> dataList;
     private boolean xssf;

     private String[] fieldNames;

     //构造方法，传入要导出的数据
     public ExportExcelTool(String title, String[] rowName, String[] fieldNames, List<Object[]> dataList, boolean xssf) {
         this.dataList = dataList;
         this.rowName = rowName;
         this.title = title;
         this.xssf = xssf;
         this.fieldNames = fieldNames;
     }

     /**
      * Create a new empty Workbook, either XSSF or HSSF depending
      * on the parameter
      *
      * @return The created workbook
      */
     public Workbook create() {
         if (xssf) {
             return XSSFWorkbookFactory.createWorkbook();
         } else {
             return HSSFWorkbookFactory.createWorkbook();
         }
     }

     /*
      * 导出数据
      * */
     public Workbook export() {
         try {
             Workbook workbook = create();                        // 创建工作簿对象
             Sheet sheet = workbook.createSheet(title);                     // 创建工作表

             // 产生表格标题行
             Row rowm = sheet.createRow(0);
             Cell cellTiltle = rowm.createCell(0);

             rowm.setHeight((short) (25 * 35)); //设置高度

             //sheet样式定义【getColumnTopStyle()/getStyle()均为自定义方法 - 在下面  - 可扩展】

             sheet.addMergedRegion(new CellRangeAddress(0, 0, 0, (rowName.length - 1)));
             cellTiltle.setCellValue(title);

             // 定义所需列数
             int fieldRow = fieldNames.length;
             Row fieldName = sheet.createRow(1);                // 在索引2的位置创建行(最顶端的行开始的第二行)

             fieldName.setHeight((short) (25 * 25)); //设置高度

             // 将列头设置到sheet的单元格中
             for (int n = 0; n < fieldRow; n++) {
                 Cell cellRowName = fieldName.createCell(n);                //创建列头对应个数的单元格
                 RichTextString text;
                 if (xssf)
                     text = new XSSFRichTextString(fieldNames[n]);
                 else
                     text = new HSSFRichTextString(fieldNames[n]);
                 cellRowName.setCellValue(text);                                    //设置列头单元格的值
             }

             // 定义所需列数
             int columnNum = rowName.length;
             Row rowRowName = sheet.createRow(2);                // 在索引2的位置创建行(最顶端的行开始的第二行)

             rowRowName.setHeight((short) (25 * 25)); //设置高度

             // 将列头设置到sheet的单元格中
             for (int n = 0; n < columnNum; n++) {
                 Cell cellRowName = rowRowName.createCell(n);                //创建列头对应个数的单元格
                 RichTextString text;
                 if (xssf)
                     text = new XSSFRichTextString(rowName[n]);
                 else
                     text = new HSSFRichTextString(rowName[n]);
                 cellRowName.setCellValue(text);                                    //设置列头单元格的值
             }

             //将查询出的数据设置到sheet对应的单元格中
             for (int i = 0; i < dataList.size(); i++) {

                 Object[] obj = dataList.get(i);//遍历每个对象
                 Row row = sheet.createRow(i + 3);//创建所需的行数

                 row.setHeight((short) (25 * 20)); //设置高度

                 for (int j = 0; j < obj.length; j++) {
                     Cell cell;   //设置单元格的数据类型
                     cell = row.createCell(j, CellType.STRING);
                     if (!"".equals(obj[j]) && obj[j] != null) {
                         cell.setCellValue(obj[j].toString());                        //设置单元格的值
                     }
                 }
             }
             //让列宽随着导出的列长自动适应
             for (int colNum = 0; colNum < columnNum; colNum++) {
                 int columnWidth = sheet.getColumnWidth(colNum) / 256;
                 for (int rowNum = 0; rowNum < sheet.getLastRowNum(); rowNum++) {
                     Row currentRow;
                     //当前行未被使用过
                     if (sheet.getRow(rowNum) == null) {
                         currentRow = sheet.createRow(rowNum);
                     } else {
                         currentRow = sheet.getRow(rowNum);
                     }
                     if (currentRow.getCell(colNum) != null) {
                         Cell currentCell = currentRow.getCell(colNum);
                         if (currentCell.getCellType() == CellType.STRING) {
                             int length = currentCell.getStringCellValue().getBytes().length;
                             if (columnWidth < length) {
                                 columnWidth = length;
                             }
                         }
                     }
                 }
                 if (colNum == 0) {
                     sheet.setColumnWidth(colNum, (columnWidth - 2) * 256);
                 } else {
                     sheet.setColumnWidth(colNum, (columnWidth + 4) * 256);
                 }

             }
 //
 //            if (workbook != null) {
 //                try {
 //                    String fileName = "C:\\Users\\yangxiaobo\\Desktop/" + new SimpleDateFormat("yyyyMMddHHmmss").format(new Date()).toString();
 //                    if (xssf)
 //                        fileName += ".xlsx";
 //                    else
 //                        fileName += ".xls";
 //                    FileOutputStream out = new FileOutputStream(fileName);
 //                    workbook.write(out);
 //                    out.close();
 //                } catch (IOException e) {
 //                    e.printStackTrace();
 //                }
 //            }

 //            String fileName = "" + new SimpleDateFormat("yyyyMMddHHmmss").format(new Date()).toString();
 //            if (xssf)
 //                fileName += ".xlsx";
 //            else
 //                fileName += ".xls";
             return workbook;
         } catch (Exception e) {
             e.printStackTrace();
         }

         return null;
     }
 }