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;
    }
}