文件下载中的若干问题之——resultType Stream

最新推荐文章于 2025-05-12 10:01:53 发布

yangzhongmin21

最新推荐文章于 2025-05-12 10:01:53 发布

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CC 4.0 BY-SA版权

文章标签： WCF JSP Excel 浏览器 Struts

本文链接：https://blog.youkuaiyun.com/yangzhongmin21/article/details/83738269

本文介绍了一种使用Struts2框架实现从查询数据到Excel文件导出的方法。通过具体的代码示例，展示了如何利用JSP页面和Struts2 Action进行文件下载，并详细解析了在Struts2中导出Excel的具体步骤。

公司项目要实现这样一个功能，将查询出来的数据导出为excel表格的形式给用户。这样的功能类似于文件下载。在

最初的jsp页面中，实现下载是这么实现的：

<%@ page contentType="text/html; charset=GB2312"%>
<%@ page import="java.io.*" %>
<html>
  <head></head>
  <body>
    <%
     OutputStream o = response.getOutputStream();
     byte[] b = new byte[500];
     File file = new File("c:/","cgx.jpg");
     //告诉浏览器文件的MIME类型，如application/octet-stream
     response.setContentType("image/jpeg");
     //客户使用保存文件的对话框，去掉这句，浏览器会调用外部程序，直接打开下载的文件
     response.setHeader("Content-Disposition", "attachment;filename=cgx.jpg");
     long fileLength = file.length();
     String length = String.valueOf(fileLength);
     response.setHeader("Content-Length", length);
     FileInputStream in = new FileInputStream(file);
     int n = 0;
     while((n = in.read(b)) != -1) {
      o.write(b,0,n);
     }
     out.clear();
     out = pageContext.pushBody();
     //不加这两句会报错：getOutputStream() has already been called for this response
    %>
  </body>
</html>

将JSP页面的最后两行代码的注释去掉，这两行代码的作用如下：

out.clear()：清空缓存的内容。

pageContext.pushBody()：参考API

public BodyContent pushBody()

Return a new BodyContent object, save the current "out" JspWriter, and update the value of the "out" attribute in the page scope attribute namespace of the PageContext.

返回一个新的BodyContent(代表一个HTML页面的BODY部分内容）
·保存JspWriter实例的对象out
·更新PageContext的out属性的内容。

然而在struts2中，action与配置文件分别为：

public String exportSheetPart(){
		this.showByRole();
		return this.exportSheet();
	}
	
	public String exportSheetTotal() {
		this.execute();
		return this.exportSheet();
	}

public String exportSheet() {
		ValueStack vs = (ValueStack)ServletActionContext.getRequest().getAttribute("struts.valueStack");
		UserUtil userUtil = (UserUtil)vs.findValue("userUtil");
		DeptUtil deptUtil = (DeptUtil)vs.findValue("deptUtil");
		CodeUtil codeUtil = (CodeUtil)vs.findValue("codeUtil");
		
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		String realpath = ServletActionContext.getServletContext().getRealPath("/jsp/common/equipTemplate.xls");
		try {
			docName = new String("设备维修.xls".getBytes("GBK"),"iso-8859-1");
			/*写out Workbook template = null;
			WorkbookSettings setting = new WorkbookSettings();
			java.util.Locale locale = new java.util.Locale("zh","CN");
			setting.setLocale(locale);
			setting.setEncoding("GBK");
			template = Workbook.getWorkbook(new File(realpath),setting);
			WritableWorkbook book = Workbook.createWorkbook(out,template);
			WritableSheet sheet = book.getSheet(0);
			
			WritableCellFormat wcf = new WritableCellFormat();
			wcf.setAlignment(Alignment.CENTRE);
			wcf.setVerticalAlignment(VerticalAlignment.CENTRE);
			wcf.setFont(new WritableFont(WritableFont.ARIAL,10,WritableFont.BOLD,false, UnderlineStyle.NO_UNDERLINE, Colour.RED));
			wcf.setBorder(Border.ALL, BorderLineStyle.THIN);
			
			WritableCellFormat ftText = new WritableCellFormat();
			ftText.setAlignment(Alignment.CENTRE);
			ftText.setVerticalAlignment(VerticalAlignment.CENTRE);
			ftText.setFont(new WritableFont(WritableFont.TIMES, 10, WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE, Colour.BLACK));
			ftText.setBorder(Border.ALL, BorderLineStyle.THIN);
			
			int row = 1;
			int index = 0;
			String tmptMaintainDeptId;
			String tmptMaintainUserId;
			String tmptFixDate;
			String tmptFixMethod;
			for(FaMaintain result : maintainList){
				if(result.getMaintainDeptId() == null) {
					tmptMaintainDeptId = "";
					tmptMaintainUserId = "";
				} else {
					tmptMaintainDeptId = result.getMaintainDeptId().toString();
					tmptMaintainUserId = result.getMaintainUserId().toString();
				}
				if(result.getFixDate() == null) {
					tmptFixDate = "";
				} else {
					tmptFixDate = result.getFixDate().toString();
				}
				if(result.getFixMethod() == null) {
					tmptFixMethod = "";
				} else {
					tmptFixMethod = result.getFixMethod();
				}
				Label indexTitle = new Label(0,row,Integer.toString(index),ftText);
				Label equipNumber = new Label(1,row,result.getFaEquipment().getEquipNumber(),ftText);
				Label status = new Label(2,row,codeUtil.name("FA_MAINTAIN_STATUS", result.getStatus()),ftText);
				Label healthStatus = new Label(3,row,codeUtil.name("FA_EQUIPMENT_HEALTH_STATUS", result.getFaEquipment().getHealthStatus()),ftText);
				Label replace = new Label(4,row,codeUtil.name("FND_YESNO", result.getReplace()),ftText);
				Label createUserId = new Label(5,row,userUtil.name(result.getCreateUserId().toString()),ftText);
				Label createDeptId = new Label(6,row,deptUtil.name(result.getCreateDeptId().toString()),ftText);
				Label createDate = new Label(7,row,result.getCreateDate().toString(),ftText);
				Label priority = new Label(8,row,codeUtil.name("FA_MAINTAIN_PRIORITY", result.getPriority()),ftText);
				Label maintainUserId = new Label(9,row,userUtil.name(tmptMaintainUserId),ftText);
				Label maintainDeptId = new Label(10,row,deptUtil.name(tmptMaintainDeptId),ftText);
				Label fixDate = new Label(11,row,tmptFixDate,ftText);
				Label fixMethod = new Label(12,row,codeUtil.name("FA_MAINTAIN_METHOD", tmptFixMethod),ftText);
				Label memo = new Label(13,row,result.getMemo(),ftText);	
				
				sheet.addCell(indexTitle);
				sheet.addCell(equipNumber);
				sheet.addCell(status);
				sheet.addCell(healthStatus);
				sheet.addCell(replace);
				sheet.addCell(createUserId);
				sheet.addCell(createDeptId);
				sheet.addCell(createDate);
				sheet.addCell(priority);
				sheet.addCell(maintainUserId);
				sheet.addCell(maintainDeptId);
				sheet.addCell(fixDate);
				sheet.addCell(fixMethod);
				sheet.addCell(memo);
				row++;
				index++;
			}
			book.write();
			book.close();*/
			exportStream = new ByteArrayInputStream(out.toByteArray());//将out转化为in的小技巧
		}catch (Exception e) {
			addActionError("导出失败");
			e.printStackTrace();
			return ERROR;
		} finally {// 正常关闭输入输出流.
			try {
				if (out != null) {
					out.flush();
					out.close();
					out = null;
				}
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return SUCCESS;
	}

		<action name="equip_export" method="exportSheetPart" class="MaintainListAction">
				<result name="success" type="stream"> 
					<param name="contentType">application/octet-stream;charset=ISO8859-1</param>
					<param name="contentDisposition">attachment;fileName="${docName}"</param>
					<param name="inputName">exportStream</param>
					<param name="bufferSize">4096</param>
				</result>
		</action>
		<action name="equip_export2" method="exportSheetTotal" class="MaintainListAction">
				<result name="success" type="stream"> 
					<param name="contentType">application/octet-stream;charset=ISO8859-1</param>
					<param name="contentDisposition">attachment;fileName="${docName}"</param>
					<param name="inputName">exportStream</param>
					<param name="bufferSize">4096</param>
				</result>
		</action>

在jsp页面中，有这样一段js

function exp(){
		var tgt = document.queryForm.target;
		var act = document.queryForm.action;
		document.queryForm.target = 'sframe';
		document.queryForm.action = 'equip_export.do';
		document.queryForm.submit();
		document.queryForm.action = act;
		document.queryForm.target = tgt;
	}

和这样一些html

<td width="40">
			<table border="0" cellpadding="0" cellspacing="0" class="ButCmd-border" onMouseOver="this.className='ButCmd2-border'" onMouseOut="this.className='ButCmd-border'" > 
			<tr> 
				<td><input name="expBtn" onclick="exp();" value="导出表格" title="导出表格" type="button"  class="btn3_mouseout" onMouseOver="this.className='btn3_mouseover'" onMouseOut="this.className='btn3_mouseout'" onMouseDown="this.className='btn3_mousedown'" onMouseUp="this.className='btn3_mouseup'" style="width:66px; height:22px;"/></td> 
			</tr> 
            </table>
			</td>
<iframe src="" name="sframe" width="100%" marginwidth="0" height="0" marginheight="0" scrolling="no" frameborder="0" id="sframe"></iframe>

Return a new BodyContent object, save the current "out" JspWriter, and update the value of the "out" attribute in the page scope attribute namespace of the PageContext.

Returns:

the new BodyContent

·返回一个新的BodyContent(代表一个HTML页面的BODY部分内容）
·保存JspWriter实例的对象out
·更新PageContext的out属性的内容

Returns:

the new BodyContent