java生成excel表格和pdf并实现下载弹出框

爱被打了一巴掌 2022-08-27 13:51 214阅读 0赞

今天在pdf和excel中都实现了在浏览器弹出下载框

将之前在网上查找的生成excel表格代码稍微修改下：

public class CreateSimpleExcelToDisk {
     /**
      * @功能：手工构建一个简单格式的Excel
      */
     private static List<News> getNews() throws Exception
     {
      List<News> data = new ArrayList<News>();
      NewsDao dao = new NewsDao();
      ArrayList<News> list=dao.queryAll();
      SimpleDateFormat df = new SimpleDateFormat("yyyy-mm-dd");
      for(News news:list){
    //	  News user1 = new News(news.getNewsId(),news.getTypeId(), news.getTitle(), news.getPublishTime(), news.getBody(),news.getTag(),news.getAuthor(),news.getClicks(),news.getImgUrl());
    	  data.add(new News(news.getNewsId(),news.getTypeId(), news.getTitle(), news.getPublishTime(), news.getBody(),news.getTag(),news.getAuthor(),news.getClicks(),news.getImgUrl()));
      }
      return list;
     }
     public void ExpExcel(OutputStream out) throws Exception{
    
    	  // 第一步，创建一个webbook，对应一个Excel文件
    	  HSSFWorkbook wb = new HSSFWorkbook();
    	  // 第二步，在webbook中添加一个sheet,对应Excel文件中的sheet
    	  HSSFSheet sheet = wb.createSheet("Sheet1");
    	  // 第三步，在sheet中添加表头第0行,注意老版本poi对Excel的行数列数有限制short
    	  HSSFRow row = sheet.createRow((int) 0);
    	  // 第四步，创建单元格，并设置值表头 设置表头居中
    	  HSSFCellStyle style = wb.createCellStyle();
    	  style.setAlignment(HSSFCellStyle.ALIGN_CENTER); // 创建一个居中格式
    	  HSSFCell cell = row.createCell((short) 0);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("newsid");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 1);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("typeid");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 2);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("title");
    	  HSSFCellStyle style2 = wb.createCellStyle();
    	  style2.setAlignment(HSSFCellStyle.ALIGN_LEFT); // 创建一个居左格式
    	  cell.setCellStyle(style2);
    	  cell = row.createCell((short) 3);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("publishtime");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 4);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("body");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 5);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("tag");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 6);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("author");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 7);
    	  // 设置编码格式
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("clicks");
    	  cell.setCellStyle(style);
    	  cell = row.createCell((short) 8);
    	  // 设置编码格式主要是解决导出中文等的乱码
    	  cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	  cell.setCellValue("imgUrl");
    	  cell.setCellStyle(style);
    	  // 第五步，写入实体数据 实际应用中这些数据从数据库得到，
    	  List list = CreateSimpleExcelToDisk.getNews();
    	  for (int i = 0; i < list.size(); i++)
    	  {
    	   row = sheet.createRow((int) i + 1);
    	   News news = (News) list.get(i);
    	   // 第四步，创建单元格，并设置值
    	   cell = row.createCell((short) 0);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getNewsId());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 1);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getTypeId());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 2);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getTitle());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 3);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getPublishTime());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 4);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getBody());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 5);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getTag());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 6);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getAuthor());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 7);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getClicks());
    	   cell.setCellStyle(style);
    	   cell = row.createCell((short) 8);
    	   // 设置编码格式
    	   cell.setEncoding(HSSFCell.ENCODING_UTF_16);
    	   cell.setCellValue(news.getImgUrl());
    	   cell.setCellStyle(style);
    	   /*row.createCell((short) 0).setCellValue( news.getNewsId());
    	   row.createCell((short) 1).setCellValue(news.getTypeId());
    	   row.createCell((short) 2).setCellValue(news.getTitle());
    	//   cell = row.createCell((short) 3);
    	//   cell.setCellValue(new SimpleDateFormat("yyyy-mm-dd").format(news.getPublishTime()));
    	   row.createCell((short) 3).setCellValue(news.getPublishTime());
    	   row.createCell((short) 4).setCellValue(news.getBody());
    	   row.createCell((short) 5).setCellValue(news.getTag());
    	   row.createCell((short) 6).setCellValue(news.getAuthor());
    	   row.createCell((short) 7).setCellValue(news.getClicks());
    	   row.createCell((short) 8).setCellValue(news.getImgUrl());*/
    	  }
    	  // 第六步，将文件存到指定位置
    	  try
    	  {
    //	   String outputFile = "E:/news.xls";
    //	   FileOutputStream fout = new FileOutputStream(outputFile);//"E:/news.xls"
    	   System.out.println("list="+list);
    	   wb.write(out);
    	   out.close();
    	  }
    	  catch (Exception e)
    	  {
    	   e.printStackTrace();
    	  }
     }
    
    } 
     用servlet实现下载：此代码可以套用 public class ExpExcelServlet extends HttpServlet {
    	public void doGet(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		String fileName = "news.et";
    		response.setContentType("octets/stream");
    		response.addHeader("Content-Disposition", "attachment;filename="
    				+ URLEncoder.encode(fileName, "utf-8"));
    		
    
    		try {
    			NewsDao dao = new NewsDao();
    			ArrayList<News> list = dao.queryAll();
    			CreateSimpleExcelToDisk ce=new CreateSimpleExcelToDisk();
    					OutputStream out = response.getOutputStream();
    				ce.ExpExcel(out);
    				out.close();
    			} catch (Exception e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    			System.out.println("et导出成功！");
    		} 
    
    	
    	public void doPost(HttpServletRequest request, HttpServletResponse response)
    			throws ServletException, IOException {
    		doGet(request,response);
    	}
    
    } 
     网上的资料 
     
      
     可以采用：
    1、RequestDispatcher的方式进行；
    2、采用文件流输出的方式下载。
    
    1、采用RequestDispatcher的方式进行
                jsp页面中添加如下代码：
               <%
          response.setContentType("application/x-download");//设置为下载application/x-download
          String filedownload = "/要下载的文件名";//即将下载的文件的相对路径
          String filedisplay = "最终要显示给用户的保存文件名";//下载文件时显示的文件保存名称
          filenamedisplay = URLEncoder.encode(filedisplay,"UTF-8");
          response.addHeader("Content-Disposition","attachment;filename=" + filedisplay);
        
          try
          {
              RequestDispatcher dis = application.getRequestDispatcher(filedownload);
              if(dis!= null)
              {
                  dis.forward(request,response);
              }
              response.flushBuffer();
          }
          catch(Exception e)
          {
              e.printStackTrace();
          }
          finally
          {
        
          }
    %>
    2、采用文件流输出的方式下载
             <%@page language="java" contentType="application/x-msdownload"    pageEncoding="gb2312"%><%
          //关于文件下载时采用文件流输出的方式处理：
          //加上response.reset()，并且所有的％>后面不要换行，包括最后一个；
          response.reset();//可以加也可以不加
          response.setContentType("application/x-download");
          String filedownload = "想办法找到要提供下载的文件的物理路径＋文件名";
          String filedisplay = "给用户提供的下载文件名";
          filedisplay = URLEncoder.encode(filedisplay,"UTF-8");
          response.addHeader("Content-Disposition","attachment;filename=" + filedisplay);
          OutputStream outp = null;
          FileInputStream in = null;
          try
          {
              outp = response.getOutputStream();
              in = new FileInputStream(filenamedownload);
              byte[] b = new byte[1024];
              int i = 0;
              while((i = in.read(b)) > 0)
              {
                  outp.write(b, 0, i);
              }
              outp.flush();
          }
          catch(Exception e)
          {
              System.out.println("Error!");
              e.printStackTrace();
          }
          finally
          {
              if(in != null)
              {
                  in.close();
                  in = null;
              }
              if(outp != null)
              {
                  outp.close();
                  outp = null;
              }
          }
    %>
    在wsad里面写JSP文件下载,总是出现这个异常,getOutputStream() has already been called for this response,输出流已经被调用了.
          上网查半天终于明白一点,JSP早下载文件的时候用到了OutputStream,而在Application Server在处理编译jsp时对于％>和<％之间的内容一般是原样输出，而且默认是PrintWriter.