我现在在做一个东西，他要求可以上传一些文件，并可以下载，我在网上找了好几天了，就是搞不好，郁闷死了．
现在把代码贴出来大家给帮下忙．

String tempfilename=(String)session.getId();
File f1=new File("E:\wangzhan_zong\GYZX\upload",tempfilename);
int n;
try
{
InputStream in=request.getInputStream();
BufferedInputStream my_in=new BufferedInputStream(in);
FileOutputStream fout=new FileOutputStream(f1);
BufferedOutputStream my_out=new BufferedOutputStream(fout);
byte[] b=new byte[10000];
while((n=my_in.read(b))!=-1)
{
my_out.write(b,0,n);
}
my_out.flush();
my_out.close();
fout.close();
my_in.close();
in.close();
out.print("文件上传成功!<br>");
}
catch(IOException e)
{
out.print("文件上传失败!");
}

try
{
RandomAccessFile random1=new RandomAccessFile(f1,"r");
random1.readLine();
String filename=random1.readLine();
byte[] b=filename.getBytes("ISO-8859-1");
filename=new String(b);
int pointer=filename.lastIndexOf('\\');
filename=filename.substring(pointer+1,filename.length()-1);
File f2=new File("E:\wangzhan_zong\GYZX\upload",filename);
RandomAccessFile random2=new RandomAccessFile(f2,"rw");
random1.seek(0);
for(int i=1; i<=4; i++)
{
String tempstr=random1.readLine();
}
long startPoint=random1.getFilePointer();
random1.seek(random1.length());
long mark=random1.getFilePointer();
int j=0;
long endPoint=0;
while((mark>=0)&&(j<=5))
{
mark--;
random1.seek(mark);
n=random1.readByte();
if(n=='\n')
{
j++;
endPoint=random1.getFilePointer();
}
}
long length=endPoint-startPoint+1;
int order=(int)(length/10000);
int left=(int)(length%10000);
byte[] c=new byte[10000];
random1.seek(startPoint);
for(int i=0; i<order; i++)
{
random1.read(c);
random2.write(c);
}
random1.read(c,0,left);
random2.write(c,0,left);
random1.close();
random2.close();
f1.delete();
out.print("文件更新成功!");
}
catch(Exception e)
{
out.print("文件更新失败!");
}
这是js代码，不知道能不能实现，如果可以的话，那HTML页面怎么实现呀．