使用IO流实现文件的下载
此处是“教学课件”的下载，因此导航栏中教学课件的代码如下：
<ul id="sliderNav"> <li class="sliderTag"><h3>教学资源</h3></li> <li class="sliderTag"><a href="../../TeachResourceServlet?flag=jiaoxuedagang" target="main">教学大纲</a></li> <li class="sliderTag"><a href="../../TeachResourceServlet?flag=jiaoxuekejian" target="main">教学课件</a></li> <li class="sliderTag"><a href="p_jiaoXueLuXiang.jsp" target="main">教学录像</a></li> <li class="sliderTag"><a href="p_moNiShiTi.jsp" target="main">模拟试题</a></li> </ul>
TeachResourceServlet中的doPost()关键代码如下：
response.setContentType("text/html; charset=utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out=response.getWriter();
String flag=request.getParameter("flag");
List<FileUploadBean> flist=new ArrayList<FileUploadBean>();
FileUploadDao fd=new FileUploadDaoImpl();
if(flag.equals("jiaoxuekejian")){
flist=fd.load();
request.setAttribute("filelist",flist);
request.getRequestDispatcher("pages/jiaoXueZiYuan/p_jiaoXueKeJian.jsp").forward(request, response);
}
DaoImpl中的load方法如下：
public List<FileUploadBean> load() {
sql="select * from uploadfile";
try{
conn=DbUtil.getConn();
st=DbUtil.getStatement(conn);
rs=DbUtil.getResultSet(st, sql);
while(rs.next()){
FileUploadBean fd=new FileUploadBean();
fd.setId(rs.getInt("id"));
fd.setFilename(rs.getString("filename"));
fd.setUfiledescr(rs.getString("ufiledescr"));
fd.setUperson(rs.getString("uperson"));
fd.setUtime(rs.getString("utime"));
list.add(fd);
}
}catch(Exception e){
e.printStackTrace();
}
finally{
DbUtil.closeRs(rs);
DbUtil.closeStmt(st);
DbUtil.closeConn(conn);
}
return list;
}
返回到页面中显示可下载的文件列表（此处用表格实现）
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ page import="com.xuan.vo.*,java.net.*;" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>教学课件</title>
<link rel="stylesheet" href="css/jq.css" type="text/css" media="print, projection, screen" />
<link rel="stylesheet" href="css/style.css" type="text/css" media="print, projection, screen" />
<script type="text/javascript" src="js/jquery-1.1.3.js"></script>
<script type="text/javascript" src="js/jquery.tablesorter.js"></script>
<script type="text/javascript" src="js/jquery.tablesorter.pager.js"></script>
<script type="text/javascript">
$(document).ready(function(){
//jQuery插件:Tablesorter 2.0 - 加jQuery分页插件控制表格分页显示
$(".table-04").tablesorter({widthFixed: true}).tablesorterPager({container: $("#pager")});
});
</script>
</head>
<body>
<div id="main">
<table cellspacing="1" class="tablesorter table-04">
<caption><h3>通知公告</h3></caption>
<thead>
<tr><th>文件</th><th>发布人</th><th>发布时间</th><th>文件描述</th><th>操作</th></tr>
</thead>
<tfoot>
<tr><th>文件</th><th>发布人</th><th>发布时间</th><th>文件描述</th><th>操作</th></tr>
</tfoot>
<tbody>
<%
List flist=(List)request.getAttribute("filelist");
FileUploadBean fb=new FileUploadBean();
%>
<%
for(int i=0;i<flist.size();i++){
fb=(FileUploadBean)flist.get(i);
int id=fb.getId();
out.print("<tr><td>"+fb.getFilename()+"</td><td>"+fb.getUperson()+"</td><td>"+fb.getUtime()+"</td><td>"+fb.getUfiledescr()+"</td><td><a href=TeachResourceServlet?flag=kejiandownload&id="+id+">下载</a></td></tr>");
}
%>
</tbody>
</table>
<div id="pager" class="pager">
<form>
<img src="images/first.png" class="first"/>
<img src="images/prev.png" class="prev"/>
<input type="text" class="pagedisplay"/>
<img src="images/next.png" class="next"/>
<img src="images/last.png" class="last"/>
<select class="pagesize">
<option selected="selected" value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
</select>
</form>
</div>
</div>
</body>
</html>
点击下载按钮之后，处理该事件的servlet如下：
if(flag.equals("kejiandownload")){
String idstr=request.getParameter("id");
int id=Integer.parseInt(idstr);
flist=fd.loadById(id);
String filename=flist.get(0).getFilename();
response.reset();//（加上就不会报Illegal...异常）
response.setContentType("application/octet-stream");
/*String fileName=new String(request.getParameter("filename").getBytes("iso8859-1"));*/
File file = new File(getServletContext().getRealPath("/") + "upload/"+ filename);
InputStream is = new FileInputStream(file);
OutputStream os = response.getOutputStream();
response.addHeader("Content-Disposition", "attachment;filename =" + new String(file.getName().getBytes("utf-8"),"iso8859-1"));
response.addHeader("Content-Length", new Long(file.length()).toString());
response.setCharacterEncoding("utf-8");
int a = 0;
while((a = is.read()) != -1){
os.write(a);
}
is.close();
os.close();
}