POI+Maven实现数据导出到Excel

关于poi的使用将数据库中的数据导出到Excel中详解

1.首先要导入poi的maven坐标

<dependency>
        <groupId>org.apache.poi</groupId>
        <artifactId>poi</artifactId>
        <version>3.14</version>
</dependency>

2.使用工具类进行下载封装，并且完成下载后单元格的样式设置，宽度随着单元格内容长度自适应，以及Excel标题的设定。

import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFFont;
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.CellRangeAddress;
import org.apache.poi.hssf.util.HSSFColor;

public class ExportExcel{

    // 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 = new ArrayList<Object[]>();

    HttpServletResponse response;

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

    /*
     * 导出数据
     */
    public void export(OutputStream out) throws Exception {
        try {
            HSSFWorkbook workbook = new HSSFWorkbook(); // 创建工作簿对象
            HSSFSheet sheet = workbook.createSheet(title); // 创建工作表
            // 产生表格标题行
            HSSFRow rowm = sheet.createRow(0);
            HSSFCell cellTiltle = rowm.createCell(0);

            // sheet样式定义【getColumnTopStyle()/getStyle()均为自定义方法 - 在下面 - 可扩展】
            HSSFCellStyle columnTopStyle = this.getColumnTopStyle(workbook);// 获取列头样式对象
            HSSFCellStyle style = this.getStyle(workbook); // 单元格样式对象
            /*
             * sheet.addMergedRegion(new
             * CellRangeAddress(0,dataList.get(0).length-1 , 0,
             * (rowName.length-1)));
             */// 合并单元格
            sheet.addMergedRegion(new CellRangeAddress(0, 1, 0,
                    dataList.get(0).length - 1));// 列行
            cellTiltle.setCellStyle(style);
            cellTiltle.setCellValue(title);

            // 定义所需列数
            int columnNum = rowName.length;
            HSSFRow rowRowName = sheet.createRow(0); // 在索引2的位置创建行(最顶端的行开始的第二行)

            // 将列头设置到sheet的单元格中
            for (int n = 0; n < columnNum; n++) {
                HSSFCell cellRowName = rowRowName.createCell(n); // 创建列头对应个数的单元格
                cellRowName.setCellType(HSSFCell.CELL_TYPE_STRING); // 设置列头单元格的数据类型
                HSSFRichTextString text = new HSSFRichTextString(rowName[n]);
                cellRowName.setCellValue(text); // 设置列头单元格的值
                cellRowName.setCellStyle(columnTopStyle); // 设置列头单元格样式
            }

            // 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
                HSSFRow row = sheet.createRow(i + 2);// 创建所需的行数（从第三行开始写数据）

                for (int j = 0; j < obj.length; j++) {
                    HSSFCell cell = null; // 设置单元格的数据类型
                    if (j == 0) {
                        cell = row.createCell(j, HSSFCell.CELL_TYPE_NUMERIC);
                        cell.setCellValue(i);
                    } else {
                        cell = row.createCell(j, HSSFCell.CELL_TYPE_STRING);
                        if (obj[j] != null) {
                            cell.setCellValue(obj[j].toString());
                        }
                    }
                    cell.setCellStyle(style); // 设置单元格样式
                }
            }
            // 让列宽随着导出的列长自动适应
            for (int colNum = 0; colNum < dataList.get(1).length; colNum++) {
                int columnWidth = sheet.getColumnWidth(colNum) / 256;
                for (int rowNum = 0; rowNum < sheet.getLastRowNum(); rowNum++) {
                    HSSFRow 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) { HSSFCell
                     * currentCell = currentRow.getCell(colNum); if
                     * (currentCell.getCellType() == HSSFCell.CELL_TYPE_STRING)
                     * { int length =
                     * currentCell.getStringCellValue().getBytes().length; if
                     * (columnWidth < length) { columnWidth = length; } } }
                     */
                    if (currentRow.getCell(colNum) != null) {
                        HSSFCell currentCell = currentRow.getCell(colNum);
                        if (currentCell.getCellType() == HSSFCell.CELL_TYPE_STRING) {
                            int length = 0;
                            try {
                                length = currentCell.getStringCellValue()
                                        .getBytes().length;
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                            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 {
                    workbook.write(out);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            out.close();
        }

    }

    /*
     * 列头单元格样式
     */
    public HSSFCellStyle getColumnTopStyle(HSSFWorkbook workbook) {

        // 设置字体
        HSSFFont font = workbook.createFont();
        // 设置字体大小
        font.setFontHeightInPoints((short) 11);
        // 字体加粗
        font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        // 设置字体名字
        font.setFontName("Courier New");
        // 设置样式;
        HSSFCellStyle style = workbook.createCellStyle();
        // 设置底边框;
        style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        // 设置底边框颜色;
        style.setBottomBorderColor(HSSFColor.BLACK.index);
        // 设置左边框;
        style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        // 设置左边框颜色;
        style.setLeftBorderColor(HSSFColor.BLACK.index);
        // 设置右边框;
        style.setBorderRight(HSSFCellStyle.BORDER_THIN);
        // 设置右边框颜色;
        style.setRightBorderColor(HSSFColor.BLACK.index);
        // 设置顶边框;
        style.setBorderTop(HSSFCellStyle.BORDER_THIN);
        // 设置顶边框颜色;
        style.setTopBorderColor(HSSFColor.BLACK.index);
        // 在样式用应用设置的字体;
        style.setFont(font);
        // 设置自动换行;
        style.setWrapText(false);
        // 设置水平对齐的样式为居中对齐;
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        // 设置垂直对齐的样式为居中对齐;
        style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

        return style;

    }

    /*
     * 列数据信息单元格样式
     */
    public HSSFCellStyle getStyle(HSSFWorkbook workbook) {
        // 设置字体
        HSSFFont font = workbook.createFont();
        // 设置字体大小
        // font.setFontHeightInPoints((short)10);
        // 字体加粗
        // font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        // 设置字体名字
        font.setFontName("Courier New");
        // 设置样式;
        HSSFCellStyle style = workbook.createCellStyle();
        // 设置底边框;
        style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
        // 设置底边框颜色;
        style.setBottomBorderColor(HSSFColor.BLACK.index);
        // 设置左边框;
        style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
        // 设置左边框颜色;
        style.setLeftBorderColor(HSSFColor.BLACK.index);
        // 设置右边框;
        style.setBorderRight(HSSFCellStyle.BORDER_THIN);
        // 设置右边框颜色;
        style.setRightBorderColor(HSSFColor.BLACK.index);
        // 设置顶边框;
        style.setBorderTop(HSSFCellStyle.BORDER_THIN);
        // 设置顶边框颜色;
        style.setTopBorderColor(HSSFColor.BLACK.index);
        // 在样式用应用设置的字体;
        style.setFont(font);
        // 设置自动换行;
        style.setWrapText(false);
        // 设置水平对齐的样式为居中对齐;
        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
        // 设置垂直对齐的样式为居中对齐;
        style.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);

        return style;

    }

}

3.使用方式

List<Map<String, Object>> list = registrationInformationDao
                .findRegistrationInformation1(map);//获取数据
        List<Object[]> dataList = new ArrayList<Object[]>();
        Object[] objects0 = new Object[list.get(0).size()+1];
        dataList.add(objects0);
        Map<String, Object> map2 = list.get(0);
        Set<String> keySet = map2.keySet();
        int m = 1;
        for (String key : keySet) {
            dataList.get(0)[m++] = key;
        }
        for (int i = 0; i < list.size(); i++) {
            Object[] objects = new Object[list.get(i).size()+1];
            dataList.add(objects);
            int j = 1;
            Map<String, Object> map3 = list.get(i);
            Set<String> keySet1 = map3.keySet();
            for (String key : keySet1) {
                dataList.get(i+1)[j++] = map3.get(key);
            }
        }
// 使用流将数据导出
OutputStream out = null;
try {
// 防止中文乱码
Parament findByName = paramentDao.findByName("export_name");

String headStr = "attachment; filename=\""
        + new String((findByName.getParament_value()+/*下载后的文件名*/".xls").getBytes("gb2312"), "ISO8859-1") + "\"";
response.setContentType("octets/stream");
response.setContentType("APPLICATION/OCTET-STREAM");
response.setHeader("Content-Disposition", headStr);
out = response.getOutputStream();
ExportExcelSeedBack ex = new ExportExcelSeedBack(findByName.getParament_value(),/*表的标题*/ new String[]{findByName.getParament_value()/*内容标题*/},
        dataList/*数据准备  ---数据类型为List<Object[]>*/);
ex.export(out);
} catch (Exception e) {
    e.printStackTrace();
}