使用poi从服务器保存数据到本地

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本文介绍了一个Java Servlet实现的用户信息导出功能，通过HTTP请求响应机制将数据库中的用户数据导出为Excel文件，并提供了文件下载。该过程涉及Spring框架、Apache POI库以及Servlet API的使用。

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import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.List;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;

/**
* 用户信息导出类
*
* @author 寇航艇
*
*/
public class UseServlet extends HttpServlet
{

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {
        doPost(request, response);
    }

    @SuppressWarnings("unchecked")
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
    {

        response.setContentType("text/html");
        // 封装页面的参数
        UserInfo bo = new UserInfo();

        // 调用业务层
        ServletContext servletContext = this.getServletContext();
        WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(servletContext);
        IUsersBus userinfo= (IUsersBus)ctx.getBean("userinfo");

        List<UserInfo> list = certUseDS.queryUses(bo, 50000, 1).getRows();
        OutputStream outs = response.getOutputStream();

        BufferedWriter bw = null;
        OutputStreamWriter osw = null;
        String fileName = "excel" + String.valueOf(System.currentTimeMillis()).substring(9, 13) + ".xls";
        String headStr = "attachment; filename=\"" + fileName + "\"";
        response.setContentType("APPLICATION/OCTET-STREAM");
        response.setHeader("Content-Disposition", headStr);
        osw = new OutputStreamWriter(outs, "GB2312");
        createExcel(list,outs);

    }

    /**
     * 将读取到的文件重新写入新的文件
     * @param output
     *
     * @param bw
     */
    public void createExcel( List<UserInfo> list, OutputStream output)
    {
        Workbook workBook = null;
        Row row = null;
        Cell cell = null;
        try
        {
            // 创建一个工作簿
            // 生成xlsx格式
            // workBook = new XSSFWorkbook();
            // 生成xls格式
            workBook = new HSSFWorkbook();
            // 创建工作表
            Sheet sheet = workBook.createSheet("users");
            // 创建excel表头
            createExcelHead(sheet.createRow(0));

            // 将数据写入excel
            for (int i = 0; i < list.size(); i++)
            {
                // 创建一行
                row = sheet.createRow(i + 1);
                int cellNo = 0;
                // 循环创建单元格
                cell = row.createCell(cellNo++);
                // 给单元格设值
                cell.setCellValue(list.get(i).getUserName());
                cell = row.createCell(cellNo++);
                cell.setCellValue(list.get(i).getBirth());
                cell = row.createCell(cellNo++);
                cell.setCellValue(list.get(i).getCreatedTime());
                cell = row.createCell(cellNo++);
                cell.setCellValue(list.get(i).getCounty());

            }
            // 将内容写入Excel
            workBook.write(output);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        finally
        {
            try
            {
                output.close();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }

    }

    /**
     * 创建excel表头
     *
     * @param row
     *            行
     */
    private void createExcelHead(Row row)
    {
        Cell cell;
        int cellNum = 0;
        // 设置标题
        cell = row.createCell(cellNum++);
        cell.setCellValue("用户名");
        cell = row.createCell(cellNum++);
        cell.setCellValue("生日");
        cell = row.createCell(cellNum++);
        cell.setCellValue("注册日期");
        cell = row.createCell(cellNum++);
        cell.setCellValue("籍贯");

    }
}