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swathi rama
java code
2 Answer(s)      2 years and 4 months ago
Posted in : Development process


Hai,I need to download the data file from database with csv format using java/servlet.I would like to download the csv file when user clicks download button.

Thanks in Advance


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June 22, 2012 at 1:44 PM


Here is an application that upload and save the file into database and allow the user to download that file.

1)page.jsp

<%@ page language="java" %>
<Html>
<HEAD><TITLE>Display file upload form to the user</TITLE></HEAD>

<BODY>
<FORM ENCTYPE="multipart/form-data" ACTION="upload.jsp" METHOD=POST>
<br><br><br>
<center><table border="2" >
<tr><center><td colspan="2"><p align="center"><B>UPLOAD THE FILE</B><center></td></tr>
<tr><td><b>Choose the file To Upload:</b>
</td>
<td><INPUT NAME="file" TYPE="file"></td></tr>
<tr><td colspan="2">
<p align="right"><INPUT TYPE="submit" VALUE="Send File" ></p></td></tr>
<table>
</center>
</FORM>
</BODY>
</HTML>

2)upload.jsp

<%@ page import="java.io.*" %>
<%@ page import="java.sql.*" %>

<%
String saveFile="";
String contentType = request.getContentType();
if ((contentType != null) && (contentType.indexOf("multipart/form-data") >= 0)) {
DataInputStream in = new DataInputStream(request.getInputStream());
int formDataLength = request.getContentLength();
byte dataBytes[] = new byte[formDataLength];
int byteRead = 0;
int totalBytesRead = 0;
while (totalBytesRead < formDataLength) {
byteRead = in.read(dataBytes, totalBytesRead,formDataLength);
totalBytesRead += byteRead;
}
String file = new String(dataBytes);
 saveFile = file.substring(file.indexOf("filename=\"") + 10);
saveFile = saveFile.substring(0, saveFile.indexOf("\n"));
saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,saveFile.indexOf("\""));
out.println(saveFile);
int lastIndex = contentType.lastIndexOf("=");
String boundary = contentType.substring(lastIndex + 1,contentType.length());
int pos;
pos = file.indexOf("filename=\"");
pos = file.indexOf("\n", pos) + 1;
pos = file.indexOf("\n", pos) + 1;
pos = file.indexOf("\n", pos) + 1;
int boundaryLocation = file.indexOf(boundary, pos) - 4;
int startPos = ((file.substring(0, pos)).getBytes()).length;
int endPos = ((file.substring(0, boundaryLocation)).getBytes()).length;

FileOutputStream fileOut = new FileOutputStream(saveFile);
fileOut.write(dataBytes, startPos, (endPos - startPos));
fileOut.flush();
fileOut.close();

%><Br><table border="2"><tr><td><b>You have successfully upload the file by the name of:</b>
<% out.println(saveFile);%></td></tr></table>
<%
Connection connection = null;
String connectionURL = "jdbc:mysql://192.168.10.112:3306/test";
ResultSet rs = null;
PreparedStatement psmnt = null;
FileInputStream fis;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
connection = DriverManager.getConnection(connectionURL, "root", "root");
File f = new File(saveFile);
psmnt = connection.prepareStatement("insert into file(file_data) values(?)");
fis = new FileInputStream(f);
psmnt.setBinaryStream(1, (InputStream)fis, (int)(f.length()));
int s = psmnt.executeUpdate();
if(s>0) {
System.out.println("Uploaded successfully !");
}
else {
System.out.println("unsucessfull to upload file.");
}
}
catch(Exception e){e.printStackTrace();}
}
%> 
<form method="post" action="../DownloadServlet">
<input type="hidden" name="f" value=<%=saveFile%>
<input type="submit" value="Download">
</form>


June 22, 2012 at 1:45 PM


continue..

3)DownloadServlet.java:

import java.io.*;
import java.net.*
import javax.servlet.*;
import javax.servlet.http.*;

public class DownloadServlet extends HttpServlet{ 
     public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
     response.setContentType("text/html");
     PrintWriter out = response.getWriter();

    String file=request.getParameter("f");
    File f = new File (file);
    String filename=f.getName();
    String type=getMimeType("file:"+file);

    response.setContentType (type);
    response.setHeader ("Content-Disposition", "attachment;     filename=\""+filename+"\"");

    String name = f.getName().substring(f.getName().lastIndexOf("/") + 1,f.getName().length());
    InputStream in = new FileInputStream(f);
        ServletOutputStream outs = response.getOutputStream();

        int bit = 256;
        int i = 0;
            try {
                    while ((bit) >= 0) {
                        bit = in.read();
                        outs.write(bit);
                    }
                        } catch (IOException ioe) {
                        ioe.printStackTrace(System.out);
                    }
                        outs.flush();
                    outs.close();
                    in.close(); 
     }
     public static String getMimeType(String fileUrl)
    throws java.io.IOException, MalformedURLException 
  {
    String type = null;
    URL u = new URL(fileUrl);
    URLConnection uc = null;
    uc = u.openConnection();
    type = uc.getContentType();
    return type;
  }
}


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