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Download an uploaded file  RSS feed

 
Bharat Raj Kumar
Greenhorn
Posts: 2
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hi....friend Now I have uploaded file into specified folder.So I have to download it....please help me...
Thank U.....
 
Paul Clapham
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Welcome to the Ranch!

It isn't clear what you mean by the "specified" folder. Could you explain that a bit more? Like, who specified it and why don't you know what it is?
 
Abhay Agarwal
Ranch Hand
Posts: 1376
Eclipse IDE Java
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Hi Bharat

Welcome to Java ranch !!

Very basic way to download a file is to perform basic I/O. Read a File using FileInputStream and then write that file contents in HTTPServletResponse outputStream.
Sample code is given below


 
Bharat Raj Kumar
Greenhorn
Posts: 2
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this is my code of uploading a file------->



HTML-->>
<form method="post" action="fileUpload.jsp" name="upform" enctype="multipart/form-data">
<table width="60%" border="0" cellspacing="1" cellpadding="1" align="center" class="style1">
<tr>
<td align="left"><b>Select a file to upload :</b></td>
</tr>
<tr>
<td align="left">
<input type="file" name="uploadfile" size="50">
</td>
</tr>
<tr>
<td align="left">
<input type="hidden" name="todo" value="upload">
<input type="submit" name="Submit" value="Upload">
<input type="reset" name="Reset" value="Cancel">
</td>
</tr>
</table>
</form>
</body>
</html>
<<------------------------>>
JSP -->>
<%@ page import="java.io.*,javax.servlet.http.HttpServletRequest,javax.servlet.ServletInputStream" %>
<%@ page import="java.io.FileWriter,java.io.IOException" %>
<%
String savePath = "", filepath = "", filename = "";
String contentType = "", fileData = "", strLocalFileName = "";
int startPos = 0;
int endPos = 0;
%>
<%!
//copy specified number of bytes from main data buffer to temp data buffer
void copyByte(byte[] fromBytes, byte[] toBytes, int start, int len)
{
for(int i=start;i<(start+len);i++)
{
toBytes[i-start] = fromBytes[i];
}
}
%>
<%
int BOF = 0, EOF = 0;
contentType = request.getContentType();
out.println("<br>Content type is :: " +contentType);
if((contentType != null) && (contentType.indexOf("multipart/form-data") >= 0))
{
DataInputStream in = new DataInputStream(request.getInputStream());
DataInputStream in1 = in;
int formDataLength = request.getContentLength();
byte dataBytes[] = new byte[formDataLength];
int byteRead = 0;
int totalBytesRead = 0;
while (totalBytesRead < formDataLength)
{
byteRead = in1.read(dataBytes, totalBytesRead, formDataLength);
totalBytesRead += byteRead;
}
out.println("<br>totalBytesRead : " + totalBytesRead + " :formDataLength = " + formDataLength);
//String file = new String(dataBytes);
//out.println("<br>FileContents:<br>////////////////////////////////////<br>" + file + "<br>////////////////////////////////<br>");

byte[] line = new byte[128];
if (totalBytesRead < 3)
{
return; //exit if file length is not sufficiently large
}

String boundary = "";
String s = "";
int count = 0;
int pos = 0;

//loop for extracting boundry of file
//could also be extracted from request.getContentType()
do
{
copyByte(dataBytes, line, count ,1); //read 1 byte at a time
count+=1;
s = new String(line, 0, 1);
fileData = fileData + s;
pos = fileData.indexOf("Content-Disposition: form-data; name=\""); //set the file name
if(pos != -1)
endPos = pos;
}while(pos == -1);
boundary = fileData.substring(startPos, endPos);

//loop for extracting filename
startPos = endPos;
do
{
copyByte(dataBytes, line, count ,1); //read 1 byte at a time
count+=1;
s = new String(line, 0, 1);
fileData = fileData + s;
pos = fileData.indexOf("filename=\"", startPos); //set the file name
if(pos != -1)
startPos = pos;
}while(pos == -1);
do
{
copyByte(dataBytes, line, count ,1); //read 1 byte at a time
count+=1;
s = new String(line, 0, 1);
fileData = fileData + s;
pos = fileData.indexOf("Content-Type: ", startPos);
if(pos != -1)
endPos = pos;
}while(pos == -1);
filename = fileData.substring(startPos + 10, endPos - 3); //to eliminate " from start & end
strLocalFileName = filename;
int index = filename.lastIndexOf("\\");
if(index != -1)
filename = filename.substring(index + 1);
else
filename = filename;

//loop for extracting ContentType
boolean blnNewlnFlag = false;
startPos = endPos; //added length of "Content-Type: "
do
{
copyByte(dataBytes, line, count ,1); //read 1 byte at a time
count+=1;
s = new String(line, 0, 1);
fileData = fileData + s;
pos = fileData.indexOf("\n", startPos);
if(pos != -1)
{
if(blnNewlnFlag == true)
endPos = pos;
else
{
blnNewlnFlag = true;
pos = -1;
}
}
}while(pos == -1);
contentType = fileData.substring(startPos + 14, endPos);

//loop for extracting actual file data (any type of file)
startPos = count + 1;
do
{
copyByte(dataBytes, line, count ,1); //read 1 byte at a time
count+=1;
s = new String(line, 0, 1);
fileData = fileData + s;
pos = fileData.indexOf(boundary, startPos); //check for end of file data i.e boundry value
}while(pos == -1);
endPos = count - boundary.length();
//file data extracted

out.println("<br><br>0. Local File Name = " + strLocalFileName);
out.println("<br><br>1. filename = " + filename);
out.println("<br>2. contentType = " + contentType);
out.println("<br>3. startPos = " + startPos);
out.println("<br>4. endPos = " + endPos);
out.println("<br>5. boundary = " + boundary);

//create destination path & save file there
String appPath = application.getRealPath("/");
out.println("<br>appPath : " + appPath);
String destFolder = appPath + "uploaded/";
filename= destFolder + filename;
FileOutputStream fileOut = new FileOutputStream(filename);
fileOut.write(dataBytes, startPos, (endPos - startPos));
fileOut.flush();
fileOut.close();
out.println("<br>File saved as >> " + filename);
//file saved at destination
//out.println("<br>File data : <br><br>**************************<br>" + (new String(dataBytes,startPos, (endPos - startPos))) + "<br><br>**************************");
}
else
{
out.println("Error in uploading ");
}

%>
<<---------------------------------------------->>



UPLOAD FOLDER LOCATION IS: C:\Users\BHARAT1\Documents\NetBeansProjects\WebApplication6\build\web\Uploaded

I have to list all files in the folder and provide download options to those files......
 
Ulf Dittmer
Rancher
Posts: 42972
73
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Streaming the files should only be necessary if the files are not in a public directory, or if not everybody should have access to all the files. Is either the case here?

Also, don't ever put IO code in JSPs, that's bad design. That code belongs in a servlet, and then all data required to render the download page should be set as request attributes when the servlet forwards the request to the JSP.
 
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