POI导出EXCEL经典实现

package org.leno.export.util;


import java.io.*;
import java.lang.reflect.*;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.text.SimpleDateFormat;
import javax.swing.JOptionPane;
import org.apache.poi.hssf.usermodel.*;
import org.apache.poi.hssf.util.HSSFColor;


/**
* 利用开源组件POI3.0.2动态导出EXCEL文档
* 转载时请保留以下信息，注明出处！
* @author leno
* @version v1.0
* @param <T> 应用泛型，代表任意一个符合javabean风格的类
* 注意这里为了简单起见，boolean型的属性xxx的get器方式为getXxx(),而不是isXxx()
* byte[]表jpg格式的图片数据
*/
public class ExportExcel<T> {


   public void exportExcel(Collection<T> dataset, OutputStream out) {
      exportExcel("测试POI导出EXCEL文档", null, dataset, out, "yyyy-MM-dd");
   }


   public void exportExcel(String[] headers, Collection<T> dataset,
         OutputStream out) {
      exportExcel("测试POI导出EXCEL文档", headers, dataset, out, "yyyy-MM-dd");
   }


   public void exportExcel(String[] headers, Collection<T> dataset,
         OutputStream out, String pattern) {
      exportExcel("测试POI导出EXCEL文档", headers, dataset, out, pattern);
   }


   /**
    * 这是一个通用的方法，利用了JAVA的反射机制，可以将放置在JAVA集合中并且符号一定条件的数据以EXCEL 的形式输出到指定IO设备上
    *
    * @param title
    *            表格标题名
    * @param headers
    *            表格属性列名数组
    * @param dataset
    *            需要显示的数据集合,集合中一定要放置符合javabean风格的类的对象。此方法支持的
    *            javabean属性的数据类型有基本数据类型及String,Date,byte[](图片数据)
    * @param out
    *            与输出设备关联的流对象，可以将EXCEL文档导出到本地文件或者网络中
    * @param pattern
    *            如果有时间数据，设定输出格式。默认为"yyy-MM-dd"
    */
   @SuppressWarnings("unchecked")
   public void exportExcel(String title, String[] headers,
         Collection<T> dataset, OutputStream out, String pattern) {
      // 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);
     
      // 声明一个画图的顶级管理器
      HSSFPatriarch patriarch = sheet.createDrawingPatriarch();
      // 定义注释的大小和位置,详见文档
      HSSFComment comment = patriarch.createComment(new HSSFClientAnchor(0, 0, 0, 0, (short) 4, 2, (short) 6, 5));
      // 设置注释内容
      comment.setString(new HSSFRichTextString("可以在POI中添加注释！"));
      // 设置注释作者，当鼠标移动到单元格上是可以在状态栏中看到该内容.
      comment.setAuthor("leno");


      //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;
      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);
            try {
                Class tCls = t.getClass();
                Method getMethod = tCls.getMethod(getMethodName,
                      new Class[] {});
                Object value = getMethod.invoke(t, new Object[] {});
                //判断值的类型后进行强制类型转换
                String textValue = null;
//              if (value instanceof Integer) {
//                 int intValue = (Integer) value;
//                 cell.setCellValue(intValue);
//              } else if (value instanceof Float) {
//                 float fValue = (Float) value;
//                 textValue = new HSSFRichTextString(
//                       String.valueOf(fValue));
//                 cell.setCellValue(textValue);
//              } else if (value instanceof Double) {
//                 double dValue = (Double) value;
//                 textValue = new HSSFRichTextString(
//                       String.valueOf(dValue));
//                 cell.setCellValue(textValue);
//              } else if (value instanceof Long) {
//                 long longValue = (Long) value;
//                 cell.setCellValue(longValue);
//              }
                if (value instanceof Boolean) {
                   boolean bValue = (Boolean) value;
                   textValue = "男";
                   if (!bValue) {
                      textValue ="女";
                   }
                } else if (value instanceof Date) {
                   Date date = (Date) value;
                   SimpleDateFormat sdf = new SimpleDateFormat(pattern);
                    textValue = sdf.format(date);
                }  else if (value instanceof byte[]) {
                   // 有图片时，设置行高为60px;
                   row.setHeightInPoints(60);
                   // 设置图片所在列宽度为80px,注意这里单位的一个换算
                   sheet.setColumnWidth(i, (short) (35.7 * 80));
                   // sheet.autoSizeColumn(i);
                   byte[] bsValue = (byte[]) value;
                   HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0,
                         1023, 255, (short) 6, index, (short) 6, index);
                   anchor.setAnchorType(2);
                   patriarch.createPicture(anchor, workbook.addPicture(
                         bsValue, HSSFWorkbook.PICTURE_TYPE_JPEG));
                } else{
                   //其它数据类型都当作字符串简单处理
                   textValue = value.toString();
                }
                //如果不是图片数据，就利用正则表达式判断textValue是否全部由数字组成
                if(textValue!=null){
                   Pattern p = Pattern.compile("^\\d+(\\.\\d+)?$");  
                   Matcher matcher = p.matcher(textValue);
                   if(matcher.matches()){
                      //是数字当作double处理
                      cell.setCellValue(Double.parseDouble(textValue));
                   }else{
                      HSSFRichTextString richString = new HSSFRichTextString(textValue);
                      HSSFFont font3 = workbook.createFont();
                      font3.setColor(HSSFColor.BLUE.index);
                      richString.applyFont(font3);
                      cell.setCellValue(richString);
                   }
                }
            } catch (SecurityException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (NoSuchMethodException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalArgumentException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } finally {
                //清理资源
            }
         }


      }
      try {
         workbook.write(out);
      } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }


   }


   public static void main(String[] args) {
      // 测试学生
      ExportExcel<Student> ex = new ExportExcel<Student>();
      String[] headers = { "学号", "姓名", "年龄", "性别", "出生日期" };
      List<Student> dataset = new ArrayList<Student>();
      dataset.add(new Student(10000001, "张三", 20, true, new Date()));
      dataset.add(new Student(20000002, "李四", 24, false, new Date()));
      dataset.add(new Student(30000003, "王五", 22, true, new Date()));
      // 测试图书
      ExportExcel<Book> ex2 = new ExportExcel<Book>();
      String[] headers2 = { "图书编号", "图书名称", "图书作者", "图书价格", "图书ISBN",
            "图书出版社", "封面图片" };
      List<Book> dataset2 = new ArrayList<Book>();
      try {
         BufferedInputStream bis = new BufferedInputStream(
                new FileInputStream("book.jpg"));
         byte[] buf = new byte[bis.available()];
         while ((bis.read(buf)) != -1) {
            //
         }
         dataset2.add(new Book(1, "jsp", "leno", 300.33f, "1234567",
                "清华出版社", buf));
         dataset2.add(new Book(2, "java编程思想", "brucl", 300.33f, "1234567",
                "阳光出版社", buf));
         dataset2.add(new Book(3, "DOM艺术", "lenotang", 300.33f, "1234567",
                "清华出版社", buf));
         dataset2.add(new Book(4, "c++经典", "leno", 400.33f, "1234567",
                "清华出版社", buf));
         dataset2.add(new Book(5, "c#入门", "leno", 300.33f, "1234567",
                "汤春秀出版社", buf));


         OutputStream out = new FileOutputStream("E:\\a.xls");
         OutputStream out2 = new FileOutputStream("E:\\b.xls");
         ex.exportExcel(headers, dataset, out);
         ex2.exportExcel(headers2, dataset2, out2);
         out.close();
         JOptionPane.showMessageDialog(null, "导出成功!");
         System.out.println("excel导出成功！");
      } catch (FileNotFoundException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
   }
}



不行，头有点晕^_^。呵呵，又是泛型，又是反射，又是正则表达式，又是重载,还有多参数列表和POI API。一下子蹦出来，实在让人吃不消。不管了，顶住看效果先。在本地运行后，我们发现在E:\\下生成了两份excel文件：学生记录和图书记录，并且中文，数字，颜色，日期，图片等等一且正常。恩，太棒了。有人看到这里开始苦脸了：喂，我怎么一运行就报错啊！呵呵，看看什么错吧！哦，找不到文件，也就是说你没有book.jpg嘛。好，拷贝一张小巧的图书图片命名为book.jpg放置到当前工程下吧。注意，您千万别把张桌面大小的图片丢进去了^_^！看到效果了吧。现在我们再来简单梳理一下代码，实际上上面就做了一个导出excel的方法和一个本地测试main()方法。并且代码的结构也很清晰，只是涉及的知识点稍微多一点。大家细心看看注释，结合要完成的功能，应该没有太大问题的。好啦，吃杯茶，擦把汗，总算把这个类消化掉，你又进步了。咦，你不是说是在WEB环境下导出的吗？别急，因为导出就是一个下载的过程。我们只需要在服务器端写一个Jsp或者Servlet组件完成输出excel到浏览器客户端的工作就好了。我们以Servlet为例，还是看代码吧：
package org.leno.export.util;


import java.io.*;
import java.util.ArrayList;
import java.util.List;


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


/**
* @author leno
* 使用servlet导出动态生成的excel文件，数据可以来源于数据库
* 这样，浏览器客户端就可以访问该servlet得到一份用java代码动态生成的excel文件
*/
public class Export extends javax.servlet.http.HttpServlet{
   static final long serialVersionUID = 1L;
  
   protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      File file = new File(getServletContext().getRealPath("WEB-INF/book.jpg"));
      response.setContentType("octets/stream");
      response.addHeader("Content-Disposition", "attachment;filename=test.xls");
      //测试图书
      ExportExcel<Book> ex = new ExportExcel<Book>();
      String[] headers = { "图书编号", "图书名称", "图书作者", "图书价格", "图书ISBN",
            "图书出版社", "封面图片" };
      List<Book> dataset = new ArrayList<Book>();
      try {
         BufferedInputStream bis = new BufferedInputStream(
               new FileInputStream(file));
         byte[] buf = new byte[bis.available()];
         while ((bis.read(buf)) != -1) {
            //将图片数据存放到缓冲数组中
         }
         dataset.add(new Book(1, "jsp", "leno", 300.33f, "1234567",
                "清华出版社", buf));
         dataset.add(new Book(2, "java编程思想", "brucl", 300.33f, "1234567",
                "阳光出版社", buf));
         dataset.add(new Book(3, "DOM艺术", "lenotang", 300.33f, "1234567",
                "清华出版社", buf));
         dataset.add(new Book(4, "c++经典", "leno", 400.33f, "1234567",
                "清华出版社", buf));
         dataset.add(new Book(5, "c#入门", "leno", 300.33f, "1234567",
                "汤春秀出版社", buf));
         OutputStream out = response.getOutputStream();
         ex.exportExcel(headers, dataset, out);
         out.close();
         System.out.println("excel导出成功！");
      } catch (FileNotFoundException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      } catch (IOException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
   } 
  
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      doGet(request, response);
   }             
}