commons-fileupload是Apache提供的一个实现文件上传下载的简单，有效途径,需要commons-io包的支持，本文是一个简单的示例
上传页面,注意设置响应头
<body>
<center>
<h1>文件上传页面</h1><hr>
<form action="${pageContext.request.contextPath }/servlet/UploadServlet" method="post" enctype="multipart/form-data">
选择文件：<input type="file" name="file1"/><br>
描述信息:<textarea rows="5" cols="45" name="discription"></textarea><br>
<input type="submit" value="上传"/>
</form>
</center>
</body>
上传的servlet
//上传文件
String upload=this.getServletContext().getRealPath("WEB-INF/upload")
String temp=this.getServletContext().getRealPath("WEB-INF/temp")
Map pmap=new HashMap()
//get client IP address
pmap.put("ip", request.getRemoteAddr())
DiskFileItemFactory factory=new DiskFileItemFactory()
//设定内存缓冲区大小 Set the memory buffer size
factory.setSizeThreshold(1024*100)
//指定临时文件目录 Specifies the directory for temporary files
factory.setRepository(new File(temp))
ServletFileUpload fileUpload=new ServletFileUpload(factory)
fileUpload.setHeaderEncoding("utf-8")
fileUpload.setFileSizeMax(1024*1024*100)
fileUpload.setSizeMax(1024*1024*200)
//set form style enctype="multipart/form-data"
if(!fileUpload.isMultipartContent(request))
{
throw new RuntimeException("请使用正确的表单进行上传")
}
//解析request
try {
List<FileItem> list= fileUpload.parseRequest(request)
//遍历list
for(FileItem item:list)
{
if(item.isFormField())
{
String name=item.getFieldName()
String value=item.getString("utf-8")
pmap.put(name, value)
}else
{
String realname=item.getName()
String arry[]=realname.split("\\")
realname=arry[arry.length-1]
System.out.println(realname)
String uuidName=UUID.randomUUID().toString()+"_"+realname
pmap.put("realname", realname)
pmap.put("uuidname", uuidName)
InputStream in=item.getInputStream()
String hash=Integer.toHexString(uuidName.hashCode())
String savepath="/WEB-INF/upload"
for(char c:hash.toCharArray())
{
upload+="/"+c
savepath+="/"+c
}
new File(upload).mkdirs()
pmap.put("savepath", savepath)
OutputStream out=new FileOutputStream(new File(upload,uuidName))
IOUtils.In2Out(in, out)
IOUtils.close(in, out)
item.delete()
}
}
} catch (Exception e) {
// TODO 自动生成的 catch 块
e.printStackTrace()
}
//向数据库中插入数据
Resourse r=new Resourse()
try {
BeanUtils.populate(r, pmap)
String sql="insert into netdisk values(null,?,?,?,?,null,?)"
QueryRunner runner=new QueryRunner(DaoUtils.getSource())
runner.update(sql,r.getUuidname(),r.getRealname(),r.getSavepath(),r.getIp(),r.getDescription())
} catch (Exception e) {
// TODO 自动生成的 catch 块
e.printStackTrace()
}
//重定向回主页
response.sendRedirect(request.getContextPath()+"/index.jsp")
为防止重名，所以使用了UUIDNAME,把文件上传到web-inf/upload文件夹下，并且将路径与文件名保存到数据库中，上传功能完成
下载实现
下载页面
<body>
<center>
<h1>下载列表</h1><hr>
<c:forEach items="${requestScope.list }" var="r">
<h2>文件名:${r.realname }<br></h2>
上传时间:${r.uploadtime }<br>
上传者IP：${r.ip }<br>
描述信息：${r.description }<br>
<a href="${pageContext.request.contextPath }/servlet/DownServlet?id=${r.id}">下载</a><br><hr>
</c:forEach>
</center>
</body>
下载实现
response.setContentType("text/html;charset=utf-8")
//获取ID
String id=request.getParameter("id")
//根据ID查找资源
String sql="select * from netdisk where id=?"
Resourse r=null
QueryRunner runner=new QueryRunner(DaoUtils.getSource())
try {
r= runner.query(sql, new BeanHandler<Resourse>(Resourse.class), id)
} catch (SQLException e) {
// TODO 自动生成的 catch 块
e.printStackTrace()
}
if(r==null)
{
response.getWriter().write("找不到该资源!!!!")
return
}else
{
//指定响应头
response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(r.getRealname(),"UTF-8"))
response.setContentType(this.getServletContext().getMimeType(r.getRealname()))
String filePath=this.getServletContext().getRealPath(r.getSavepath()+"/"+r.getUuidname())
InputStream in=new FileInputStream(filePath)
OutputStream out=response.getOutputStream()
IOUtils.In2Out(in, out)
IOUtils.close(in, null)
}
上传下载完成，注意，下载时一定要指定两个响应头
IO工具类
public class IOUtils {
private IOUtils() {
}
public static void In2Out(InputStream in,OutputStream out) throws IOException{
byte [] bs = new byte[1024];
int i = 0;
while((i=in.read(bs))!=-1){
out.write(bs,0,i);
}
}
public static void close(InputStream in,OutputStream out){
if(in!=null){
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}finally{
in = null;
}
}
if(out!=null){
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}finally{
out = null;
}
}
}
}
完成