how to write a jsp to upload a file. if i write a form that contain

<form name='file_upload' action='file_upload.jsp' method='post'>
<input type=file name='load_file_name'>
<input type=submit name='submit' value='submit'>
</form>

then, how to write file_upload.jsp to receive the file, e.g. file.txt

 

 

To upload a file, you will need a webpage that contains a FORM with ENCTYPE set to "multipart/form-data" and contains a INPUT of type FILE. You will also need something to parse the multipart/form-data.

The basic form:
<FORM METHOD="POST" ENCTYPE="multipart/form-data" ACTION="fileupload.jsp">

<INPUT TYPE="FILE" NAME="UploadedFile">

</FORM>

As for parsing the multi-part-data, I recommend the MultipartParser from O'Reilly:

http://www.servlets.com/cos/

Hope this helps,
Chris

 

 

No, do NOT use the O'Reilly stuff. It has a quirk in the license - if you want to use it for commercial purposes, you are required to buy an O'Reilly book.

Use Apache Jakarta Commons FileUpload instead:
http://jakarta.apache.org/commons/fileupload/

 

 

jsp file upload code (any type of file): (fileUpload.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>File Contents:<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 + "images/banner/";
		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 ");
	}
	
%>

supporting html file:

 
<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>