import java.io.IOException;

import java.io.OutputStream;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.Iterator;

import java.util.List;

import java.util.logging.Level;

import java.util.logging.Logger;

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.HSSFColor;

/**

 * @author yan

 * @param <T>

 * @date 2016-12-6 20:38:24

 * @version V1.0

 * @desc

 */

public class ExcelUtil<T> {

    public HSSFWorkbook exportExcel(String title, String[] headers, List<T> dataset) {

        // 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15个字节

        sheet.setDefaultColumnWidth((short) 15);  

        // 生成一个样式

        HSSFCellStyle style = workbook.createCellStyle();

        // 设置这些样式

        style.setFillForegroundColor(HSSFColor.SKY_BLUE.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);

        // 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);

        // 产生表格标题行

        HSSFRow row = sheet.createRow(0);

        for (short i = 0; i < headers.length; i++) {

            HSSFCell cell = row.createCell(i);

            cell.setCellStyle(style);

            HSSFRichTextString text = new HSSFRichTextString(headers[i]);

            cell.setCellValue(text);

        }

        // 遍历集合数据，产生数据行

        Iterator<T> it = dataset.iterator();

        int index = 0;

        try {

            while (it.hasNext()) {

                index++;

                row = sheet.createRow(index);

                T t = (T) it.next();

                // 利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值

                Field[] fields = t.getClass().getDeclaredFields();

                for (short i = 0; i < fields.length; i++) {

                    HSSFCell cell = row.createCell(i);

                    cell.setCellStyle(style2);

                    Field field = fields[i];

                    String fieldName = field.getName();

                    String getMethodName = "get"

                            + fieldName.substring(0, 1).toUpperCase()

                            + fieldName.substring(1);

                    Class tCls = t.getClass();

                    Method getMethod = tCls.getMethod(getMethodName, new Class[]{});

                    Object value = getMethod.invoke(t, new Object[]{});

                    //全部当做字符串来处理

                    String textValue = value.toString();

                    if (textValue != null) {

                        HSSFRichTextString richString = new HSSFRichTextString(textValue);

                        HSSFFont font3 = workbook.createFont();

                        font3.setColor(HSSFColor.BLUE.index);

                        richString.applyFont(font3);

                        cell.setCellValue(richString);

                    }

                }

            }

        } catch (NoSuchMethodException ex) {

            Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex);

        } catch (SecurityException ex) {

            Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex);

        } catch (IllegalAccessException ex) {

            Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex);

        } catch (IllegalArgumentException ex) {

            Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex);

        } catch (InvocationTargetException ex) {

            Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex);

        }

        return workbook;

    }

}

import java.io.IOException;

import java.io.OutputStream;

import java.io.UnsupportedEncodingException;

import java.net.URLEncoder;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.codec.binary.Base64;

import org.apache.poi.hssf.usermodel.HSSFWorkbook;

/**

 *

 * @author yan

 */

public class NewServlet extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setHeader("Connection", "close");

        response.setHeader("Content-Type", "application/vnd.ms-excel;charset=UTF-8");

        String filename = System.currentTimeMillis() + "学生信息.xls";

        filename = encodeFileName(request, filename);

        response.setHeader("Content-Disposition", "attachment;filename=" + filename);

        OutputStream out = null;

        try {

            String[] headers = { "姓名", "年龄"};

            List<Student> dataset = new ArrayList<Student>();

            dataset.add(new Student("张三张三张三张三张三张三", "20"));

            dataset.add(new Student("李四", "24"));

            dataset.add(new Student("王五王五王五王五王五王五王五王五", "2211111111111123213")); 

            ExcelUtil<Student> eu = new ExcelUtil<Student>();

            HSSFWorkbook workbook = eu.exportExcel("发票领用",headers,dataset);

            out = response.getOutputStream();

            workbook.write(out);

        } finally {

            if(out!=null){

                out.close();

            }

        }

    }

    public String encodeFileName(HttpServletRequest request, String fileName) throws UnsupportedEncodingException {

        String agent = request.getHeader("USER-AGENT");

        if (null != agent && -1 != agent.indexOf("MSIE")) {

            return URLEncoder.encode(fileName, "UTF-8");

        } else if (null != agent && -1 != agent.indexOf("Mozilla")) {

            return "=?UTF-8?B?"+ (new String(Base64.encodeBase64(fileName.getBytes("UTF-8")))) + "?=";

        } else {

            return fileName;

        }

    }

    @Override

    protected void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        processRequest(request, response);

    }

    @Override

    protected void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        processRequest(request, response);

    }

}